* EM workbench support for VoxHenry

- Works, with Python3, in FreeCAD 18.1/18.2/19.0 beta
- Usage of Coin3d for shell represenation of voxelized geometries
- Fix for FasterCap export in sorting vertices

EM.py

@@ -63,8 +63,11 @@ from EM_FHPort import *
 from EM_FHEquiv import *
 from EM_FHSolver import *
 from EM_FHInputFile import *
-## VoxHenry specific
-#from EM_VHSolver import *
+# VoxHenry specific
+from EM_VHSolver import *
+from EM_VHConductor import *
+from EM_VHPort import *
+from EM_VHInputFile import *
 
 # for debugging
 #import EM_Globals
@@ -103,3 +106,12 @@ from EM_FHInputFile import *
 #import EM_VHSolver
 #reload(EM_VHSolver)
 #from EM_VHSolver import *
+#import EM_VHConductor
+#reload(EM_VHConductor)
+#from EM_VHConductor import *
+#import EM_VHPort
+#reload(EM_VHPort)
+#from EM_VHPort import *
+#import EM_VHInputFile
+#reload(EM_VHInputFile)
+#from EM_VHInputFile import *

EM_FHInputFile.py

@@ -73,7 +73,7 @@ def createFHInputFile(doc=None,filename=None,folder=None):
          createFHInputFile()
 '''
     if not doc:
-        doc = App.ActiveDocument
+        doc = FreeCAD.ActiveDocument
     if not doc:
         FreeCAD.Console.PrintWarning(translate("EM","No active document available. Aborting."))
         return
@@ -92,7 +92,7 @@ def createFHInputFile(doc=None,filename=None,folder=None):
         # (this should be the standard way)
         if solver.Filename == "":
             # build a filename concatenating the document name
-            solver.Filename = doc.Name + EMFHSOLVER_DEF_FILENAME
+            solver.Filename = doc.Name + EM.EMFHSOLVER_DEF_FILENAME
         filename = solver.Filename
     else:
         # otherwise, if the user passed a filename to the function, update it in the 'solver' object

EM_FHPath.py

@@ -110,7 +110,7 @@ class _FHPath:
     def __init__(self, obj):
         ''' Add properties '''
         obj.addProperty("App::PropertyLink", "Base", "EM", QT_TRANSLATE_NOOP("App::Property","The base object this component is built upon"))
-        obj.addProperty("App::PropertyLinkList","Nodes","EM",QT_TRANSLATE_NOOP("App::Property","The list of FHNodes along the path. Not for direct user modification."))
+        obj.addProperty("App::PropertyLinkList","Nodes","EM",QT_TRANSLATE_NOOP("App::Property","The list of FHNodes along the path (read only)"),1)
         obj.addProperty("App::PropertyLength","Width","EM",QT_TRANSLATE_NOOP("App::Property","Path width ('w' segment parameter)"))
         obj.addProperty("App::PropertyLength","Height","EM",QT_TRANSLATE_NOOP("App::Property","Path height ('h' segment parameter)"))
         obj.addProperty("App::PropertyInteger","Discr","EM",QT_TRANSLATE_NOOP("App::Property","Max number of segments into which curves will be discretized"))
@@ -120,11 +120,6 @@ class _FHPath:
         obj.addProperty("App::PropertyInteger","nwinc","EM",QT_TRANSLATE_NOOP("App::Property","Number of filaments in the width direction ('nwinc' segment parameter)"))
         obj.addProperty("App::PropertyInteger","rh","EM",QT_TRANSLATE_NOOP("App::Property","Ratio of adjacent filaments in the height direction ('rh' segment parameter)"))
         obj.addProperty("App::PropertyInteger","rw","EM",QT_TRANSLATE_NOOP("App::Property","Ratio of adjacent filaments in the width direction ('rw' segment parameter)"))
-        # Setting the Nodes property to read-only. The user should not directly handle this.
-        #0 -- default mode, read and write
-        #1 -- read-only
-        #2 -- hidden
-        obj.setEditorMode("Nodes", 1)
         obj.Proxy = self
         self.Type = "FHPath"
         obj.Discr = EMFHPATH_DEF_DISCR

EM_FHSegment.py

@@ -81,15 +81,15 @@ def makeFHSegment(baseobj=None,nodeStart=None,nodeEnd=None,width=None,height=Non
         _ViewProviderFHSegment(obj.ViewObject)
         # set base ViewObject properties to user-selected values (if any)
     # check if 'nodeStart' is a FHNode, and if so, assign it as segment start node
-    if nodeStart:
+    if nodeStart is not None:
         if Draft.getType(nodeStart) == "FHNode":
             obj.NodeStart = nodeStart
     # check if 'nodeEnd' is a FHNode, and if so, assign it as segment end node
-    if nodeEnd:
+    if nodeEnd is not None:
         if Draft.getType(nodeEnd) == "FHNode":
             obj.NodeEnd = nodeEnd            
     # check if 'baseobj' is a wire (only base object allowed), and only if not passed any node
-    if baseobj and not obj.NodeStart and not obj.NodeEnd:
+    if (baseobj is not None) and (obj.NodeStart is None and obj.NodeEnd is None):
         if Draft.getType(baseobj) == "Wire":
             if len(baseobj.Shape.Vertexes) == 2:
                 import EM_FHNode

EM_FHSolver.py

@@ -112,9 +112,6 @@ def makeFHSolver(units=None,sigma=None,nhinc=None,nwinc=None,rh=None,rw=None,fmi
         obj.Sigma = sigma
     else:
         # use default sigma, but scale it according to the chosen units of measurement
-        mylist = EMFHSOLVER_UNITS
-        unitindex = mylist.index('mm')
-        unitindex  = EMFHSOLVER_UNITS.index("mm")
         obj.Sigma = EMFHSOLVER_DEF_SEGSIGMA * EMFHSOLVER_UNITS_VALS[EMFHSOLVER_UNITS.index(obj.Units)]
     if nhinc:
         obj.nhinc = nhinc

EM_Globals.py

@@ -29,12 +29,10 @@ __title__="FreeCAD E.M. Workbench global definitions"
 __author__ = "FastFieldSolvers S.R.L."
 __url__ = "http://www.fastfieldsolvers.com"
 
-from FreeCAD import Vector
-
 # defines
 #
 # version information
-EM_VERSION = '1.0.1'
+EM_VERSION = '2.0.0'
 # default node color
 EMFHNODE_DEF_NODECOLOR = (1.0,0.0,0.0)
 # tolerance in degrees when verifying if vectors are parallel
@@ -42,8 +40,22 @@ EMFHSEGMENT_PARTOL = 0.01
 # tolerance in length
 EMFHSEGMENT_LENTOL = 1e-8
 
-import FreeCAD, Part
+import FreeCAD, Part, Draft
 from FreeCAD import Vector
+import EM
+
+if FreeCAD.GuiUp:
+    import FreeCADGui
+    from PySide import QtCore, QtGui
+    from DraftTools import translate
+    from PySide.QtCore import QT_TRANSLATE_NOOP
+else:
+    # \cond
+    def translate(ctxt,txt, utf8_decode=False):
+        return txt
+    def QT_TRANSLATE_NOOP(ctxt,txt):
+        return txt
+    # \endcond
     
 def getAbsCoordBodyPart(obj,position):
     ''' Retrieve the absolute coordinates of a point belonging to an object, even if in a Body or Part
@@ -140,3 +152,31 @@ def makeSegShape(n1,n2,width,height,ww):
     segShell = Part.makeShell([face1,face2,face3,face4,face5,face6])
     return segShell   
 
+def getVHSolver(createIfNotExisting=False):
+    ''' Retrieves the VHSolver object.
+    
+        'createIfNotExisting' if True forces the creation of a VHSolver object,
+            if not already existing
+            
+        Returns the VHSolver object of the current Document. If more than one VHSolver object is present,
+        return the first one.
+'''
+    # get the document containing this object
+    doc = FreeCAD.ActiveDocument
+    if doc is None:
+        FreeCAD.Console.PrintWarning(translate("EM","No active document available. Cannot get any VHSolver object."))
+        return None
+    solver = [obj for obj in doc.Objects if Draft.getType(obj) == "VHSolver"]
+    if solver == []:
+        if createIfNotExisting == True:
+            solver = EM.makeVHSolver()
+            if solver is None:
+                FreeCAD.Console.PrintError(translate("EM","Cannot create VHSolver!"))
+        else:
+            FreeCAD.Console.PrintWarning(translate("EM","Cannot get VHSolver. Is at least one VHSolver object existing?"))
+            return None
+    else:
+        # take the first in the list
+        solver = solver[0]
+    return solver
+

EM_VHConductor.py

@@ -0,0 +1,953 @@
+#***************************************************************************
+#*                                                                         *
+#*   Copyright (c) 2019                                                    *
+#*   FastFieldSolvers S.R.L., http://www.fastfieldsolvers.com              *
+#*                                                                         *
+#*   This program is free software; you can redistribute it and/or modify  *
+#*   it under the terms of the GNU Lesser General Public License (LGPL)    *
+#*   as published by the Free Software Foundation; either version 2 of     *
+#*   the License, or (at your option) any later version.                   *
+#*   for detail see the LICENCE text file.                                 *
+#*                                                                         *
+#*   This program is distributed in the hope that it will be useful,       *
+#*   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+#*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+#*   GNU Library General Public License for more details.                  *
+#*                                                                         *
+#*   You should have received a copy of the GNU Library General Public     *
+#*   License along with this program; if not, write to the Free Software   *
+#*   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+#*   USA                                                                   *
+#*                                                                         *
+#***************************************************************************
+
+
+__title__="FreeCAD E.M. Workbench VoxHenry Conductor Class"
+__author__ = "FastFieldSolvers S.R.L."
+__url__ = "http://www.fastfieldsolvers.com"
+
+# copper conductivity 1/(m*Ohms)
+EMVHSOLVER_DEF_SIGMA = 5.8e7
+
+import FreeCAD, FreeCADGui, Part, Draft, DraftGeomUtils, os
+import DraftVecUtils
+import Mesh
+from EM_Globals import getVHSolver
+from FreeCAD import Vector
+import numpy as np
+import time
+from pivy import coin
+
+if FreeCAD.GuiUp:
+    import FreeCADGui
+    from PySide import QtCore, QtGui
+    from DraftTools import translate
+    from PySide.QtCore import QT_TRANSLATE_NOOP
+else:
+    # \cond
+    def translate(ctxt,txt, utf8_decode=False):
+        return txt
+    def QT_TRANSLATE_NOOP(ctxt,txt):
+        return txt
+    # \endcond
+
+__dir__ = os.path.dirname(__file__)
+iconPath = os.path.join( __dir__, 'Resources' )
+
+def makeVHConductor(baseobj=None,name='VHConductor'):
+    ''' Creates a VoxHenry Conductor (a voxelized solid object)
+
+        'baseobj' is the 3D solid object on which the conductor is based.
+            If no 'baseobj' is given, the user must assign a base
+            object later on, to be able to use this object.
+            The 'baseobj' is mandatory, and can be any 3D solid object
+        'name' is the name of the object
+
+    Example:
+        cond = makeVHConductor(mySolid)
+'''
+    # to check if the object fits into the VHSolver bbox, we must retrieve
+    # the global bbox *before* the new VHConductor is created.
+    # get the VHSolver object; if not existing, create it
+    solver = getVHSolver(True)
+    if solver is not None:
+        gbbox = solver.Proxy.getGlobalBBox()
+        condIndex = solver.Proxy.getNextCondIndex()
+    else:
+        FreeCAD.Console.PrintWarning(translate("EM","As we found no valid VHSolver object, conductor index is set to 1. This may create issues in simulation (multiple VHConductors with the same conductor index)"))
+        condIndex = 1
+    # now create the object
+    obj = FreeCAD.ActiveDocument.addObject("Part::FeaturePython", name)
+    obj.Label = translate("EM", name)
+    # this adds the relevant properties to the object
+    #'obj' (e.g. 'Base' property) making it a _VHConductor
+    _VHConductor(obj)
+    # now we have the properties, init condIndex
+    obj.CondIndex = condIndex
+    # manage ViewProvider object
+    if FreeCAD.GuiUp:
+        _ViewProviderVHConductor(obj.ViewObject)
+        # set base ViewObject properties to user-selected values (if any)
+    # check if 'baseobj' is a solid object
+    if baseobj is not None:
+        # if right type of base
+        if not baseobj.isDerivedFrom("Part::Feature"):
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor can only be based on objects derived from Part::Feature"))
+            return
+        # check validity
+        if baseobj.Shape.isNull():
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor base object shape is null"))
+            return
+        if not baseobj.Shape.isValid():
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor base object shape is invalid"))
+            return
+        obj.Base = baseobj
+        # check if the object fits into the VHSolver bbox, otherwise must flag the voxel space as invalid
+        if solver is not None:
+            bbox = baseobj.Shape.BoundBox
+            if gbbox.isValid() and bbox.isValid():
+                if not gbbox.isInside(bbox):
+                    # invalidate voxel space
+                    solver.Proxy.flagVoxelSpaceInvalid()
+        # hide the base object
+        if FreeCAD.GuiUp:
+            obj.Base.ViewObject.hide()
+    # return the newly created Python object
+    return obj
+
+class _VHConductor:
+    '''The EM VoxHenry Conductor object'''
+    def __init__(self, obj):
+        # save the object in the class, to store or retrieve specific data from it
+        # from within the class
+        self.Object = obj
+        ''' Add properties '''
+        obj.addProperty("App::PropertyLink", "Base", "EM", QT_TRANSLATE_NOOP("App::Property","The base object this component is built upon"))
+        obj.addProperty("App::PropertyFloat","Sigma","EM",QT_TRANSLATE_NOOP("App::Property","Conductor conductivity (S/m)"))
+        obj.addProperty("App::PropertyLength","Lambda","EM",QT_TRANSLATE_NOOP("App::Property","Superconductor London penetration depth (m)"))
+        obj.addProperty("App::PropertyBool","ShowVoxels","EM",QT_TRANSLATE_NOOP("App::Property","Show the voxelization"))
+        obj.addProperty("App::PropertyInteger","CondIndex","EM",QT_TRANSLATE_NOOP("App::Property","Voxel space VHConductor index number (read-only)"),1)
+        obj.addProperty("App::PropertyBool","isVoxelized","EM",QT_TRANSLATE_NOOP("App::Property","Flags if the conductor has been voxelized (read only)"),1)
+        obj.ShowVoxels = False
+        obj.Proxy = self
+        obj.isVoxelized = False
+        obj.Sigma = EMVHSOLVER_DEF_SIGMA
+        self.shapePoints = []
+        self.Type = "VHConductor"
+
+    def onChanged(self, obj, prop):
+        ''' take action if an object property 'prop' changed
+    '''
+        #FreeCAD.Console.PrintWarning("\n_VHConductor onChanged(" + str(prop)+")\n") #debug
+        # on restore, self.Object is not there anymore (JSON does not serialize complex objects
+        # members of the class, so __getstate__() and __setstate__() skip them);
+        # so we must "re-attach" (re-create) the 'self.Object'
+        if not hasattr(self,"Object"):
+            self.Object = obj
+        # if just changed non-shape affecting properties, clear the recompute flag (not needed)
+        #if prop == "Sigma" or prop == "Lambda":
+        #    obj.purgeTouched()
+
+    def execute(self, obj):
+        ''' this method is mandatory. It is called on Document.recompute()
+    '''
+        #FreeCAD.Console.PrintWarning("_VHConductor execute()\n") #debug
+        # the class needs a 'Base' object
+        if obj.Base is None:
+            return
+        # if right type of base
+        if not obj.Base.isDerivedFrom("Part::Feature"):
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor can only be based on objects derived from Part::Feature"))
+            return
+        # check validity
+        if obj.Base.Shape.isNull():
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor base object shape is null"))
+            return
+        if not obj.Base.Shape.isValid():
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor base object shape is invalid"))
+            return
+        shape = None
+        # Check if the user selected to see the voxelization, and if the voxelization exists
+        if obj.ShowVoxels == True:
+            # get the VHSolver object
+            solver = getVHSolver()
+            if solver is not None:
+                gbbox = solver.Proxy.getGlobalBBox()
+                delta = solver.Proxy.getDelta()
+                # getting the voxel space may cause the voxelization of this VHConductor to become invalid,
+                # if the global bounding box is found to have changed, or VHSolver 'Delta' changed over time, etc.
+                voxelSpace = solver.Proxy.getVoxelSpace()
+                if obj.isVoxelized == False:
+                    FreeCAD.Console.PrintWarning(translate("EM","Cannot fulfill 'ShowVoxels', VHConductor object has not been voxelized, or voxelization is now invalid (e.g. change in voxel space dimensions). Voxelize it first."))
+                else:
+                    shape = self.createVoxelShellFastCoin(obj.Base,obj.CondIndex,gbbox,delta,voxelSpace)
+        if shape is None:
+            # if we don't show the voxelized view of the object, let's show the bounding box
+            self.shapePoints = []
+            bbox = obj.Base.Shape.BoundBox
+            if bbox.isValid():
+                shape = Part.makeBox(bbox.XLength,bbox.YLength,bbox.ZLength,Vector(bbox.XMin,bbox.YMin,bbox.ZMin))
+                # and finally assign the shape (but only if we were able to create any)
+                obj.Shape = shape
+        else:
+            # make a dummy empty shape. Representation is through custom coin3d scenegraph.
+            obj.Shape = Part.makeShell([])
+        #if FreeCAD.GuiUp:
+            # force shape recompute (even if we are using directly coin here)
+        #    _ViewProviderVHConductor.updateData(obj.ViewObject.Proxy,obj.ViewObject,"Shape")
+        #FreeCAD.Console.PrintWarning("_VHConductor execute() ends\n") #debug
+
+    def createVoxelShell(self,obj,condIndex,gbbox,delta,voxelSpace=None):
+        ''' Creates a shell composed by the external faces of a voxelized object.
+
+            'obj' is the object whose shell must be created
+            'condIndex' (int16) is the index of the object. It defines the object conductivity.
+            'gbbox' (FreeCAD.BoundBox) is the overall bounding box
+            'delta' is the voxels size length
+            'voxelSpace' (Numpy 3D array) is the voxel tensor of the overall space
+            
+            This version uses a standard Part::Shell
+
+            Remark: the VHConductor must have already been voxelized
+    '''
+        if voxelSpace is None:
+            return None
+        if not hasattr(obj,"Shape"):
+            return None
+        if self.Object.isVoxelized == False:
+            return None
+        surfList = []
+        # get the object's bbox
+        bbox = obj.Shape.BoundBox
+        if not gbbox.isInside(bbox):
+            FreeCAD.Console.PrintError(translate("EM","Conductor bounding box is larger than the global bounding box. Cannot voxelize conductor shell.\n"))
+            return
+        # now must find the voxel set that contains the object bounding box
+        # find the voxel that contains the bbox min point
+        min_x = int((bbox.XMin - gbbox.XMin)/delta)
+        min_y = int((bbox.YMin - gbbox.YMin)/delta)
+        min_z = int((bbox.ZMin - gbbox.ZMin)/delta)
+        # find the voxel that contains the bbox max point
+        # (if larger than the voxelSpace, set to voxelSpace max dim,
+        # we already verified that 'bbox' fits into 'gbbox')
+        vs_size = voxelSpace.shape
+        max_x = min(int((bbox.XMax - gbbox.XMin)/delta), vs_size[0]-1)
+        max_y = min(int((bbox.YMax - gbbox.YMin)/delta), vs_size[1]-1)
+        max_z = min(int((bbox.ZMax - gbbox.ZMin)/delta), vs_size[2]-1)
+        # array to find the six neighbour
+        sides = [(1,0,0), (-1,0,0), (0,1,0), (0,-1,0), (0,0,1), (0,0,-1)]
+        # vertexes of the six faces
+        vertexes = [[Vector(delta,0,0), Vector(delta,delta,0), Vector(delta,delta,delta), Vector(delta,0,delta)],
+                    [Vector(0,0,0), Vector(0,0,delta), Vector(0,delta,delta), Vector(0,delta,0)],
+                    [Vector(0,delta,0), Vector(0,delta,delta), Vector(delta,delta,delta), Vector(delta,delta,0)],
+                    [Vector(0,0,0), Vector(delta,0,0), Vector(delta,0,delta), Vector(0,0,delta)],
+                    [Vector(0,0,delta), Vector(delta,0,delta), Vector(delta,delta,delta), Vector(0,delta,delta)],
+                    [Vector(0,0,0), Vector(0,delta,0), Vector(delta,delta,0), Vector(delta,0,0)]]
+        # get the base point
+        vbase = Vector(gbbox.XMin + min_x * delta, gbbox.YMin + min_y * delta, gbbox.ZMin + min_z * delta)
+        FreeCAD.Console.PrintMessage(translate("EM","Starting voxel shell creation for object ") + obj.Label + "...\n")
+        # make a progress bar - commented out as not working properly
+        # total number of voxels to scan is
+        #totalVox = (max_x-min_x) * (max_y-min_y) * (max_z-min_z)
+        #stepProg = totalVox / 100.0
+        #progIndex = 0
+        #progBar = FreeCAD.Base.ProgressIndicator()
+        #progBar.start(translate("EM","Voxelizing object ") + obj.Label ,100)
+        for step_x in range(min_x,max_x+1):
+            vbase.y = gbbox.YMin + min_y * delta
+            for step_y in range(min_y,max_y+1):
+                # advancing the progress bar. Doing it only in the y loop for optimization
+                #if (step_x-min_x)*(max_y-min_y)*(max_z-min_z) + (step_y-min_y)*(max_z-min_z) > stepProg * progIndex:
+                #    progBar.next()
+                #    progIndex = progIndex + 1
+                vbase.z = gbbox.ZMin + min_z * delta
+                for step_z in range(min_z,max_z+1):
+                    # check if voxel is belonging to the given object
+                    if voxelSpace[step_x,step_y,step_z] == condIndex:
+                        # scan the six neighbour voxels, to see if they are belonging to the same conductor or not.
+                        # If they are not belonging to the same conductor, or if the voxel space is finished, the current voxel
+                        # side in the direction of the empty voxel is an external surface
+                        for side, vertex in zip(sides,vertexes):
+                            is_surface = False
+                            nextVoxelIndexes = [step_x+side[0],step_y+side[1],step_z+side[2]]
+                            if (nextVoxelIndexes[0] > max_x or nextVoxelIndexes[0] < 0 or
+                               nextVoxelIndexes[1] > max_y or nextVoxelIndexes[1] < 0 or
+                               nextVoxelIndexes[2] > max_z or nextVoxelIndexes[2] < 0):
+                                is_surface = True
+                            else:
+                                if voxelSpace[nextVoxelIndexes[0],nextVoxelIndexes[1],nextVoxelIndexes[2]] != condIndex:
+                                    is_surface = True
+                            if is_surface == True:
+                                # create the face
+                                # calculate the vertexes
+                                v11 = vbase + vertex[0]
+                                v12 = vbase + vertex[1]
+                                v13 = vbase + vertex[2]
+                                v14 = vbase + vertex[3]
+                                # now make the face
+                                poly = Part.makePolygon( [v11,v12,v13,v14,v11])
+                                face = Part.Face(poly)
+                                surfList.append(face)
+                    vbase.z += delta
+                vbase.y += delta
+            vbase.x += delta
+        #progBar.stop()
+        FreeCAD.Console.PrintMessage(translate("EM","Voxelization of the shell completed.\n"))
+        # create a shell. Does not need to be solid.
+        objShell = Part.makeShell(surfList)
+        return objShell
+
+    def createVoxelShellFast(self,obj,condIndex,gbbox,delta,voxelSpace=None):
+        ''' Creates a shell composed by the external faces of a voxelized object.
+
+            'obj' is the object whose shell must be created
+            'condIndex' (int16) is the index of the object. It defines the object conductivity.
+            'gbbox' (FreeCAD.BoundBox) is the overall bounding box
+            'delta' is the voxels size length
+            'voxelSpace' (Numpy 3D array) is the voxel tensor of the overall space
+
+            This version uses a standard Part::Shell, but calculates the VHConductor
+            boundaries by finite differences over the voxel conductor space,
+            for speed in Python. However the speed bottleneck is still the
+            use of the Part::Shell via OpenCascade
+
+            Remark: the VHConductor must have already been voxelized
+    '''
+        if voxelSpace is None:
+            return None
+        if not hasattr(obj,"Shape"):
+            return None
+        if self.Object.isVoxelized == False:
+            return None
+        surfList = []
+        # get the object's bbox
+        bbox = obj.Shape.BoundBox
+        if not gbbox.isInside(bbox):
+            FreeCAD.Console.PrintError(translate("EM","Conductor bounding box is larger than the global bounding box. Cannot voxelize conductor shell.\n"))
+            return
+        # now must find the voxel set that contains the object bounding box
+        # find the voxel that contains the bbox min point
+        min_x = int((bbox.XMin - gbbox.XMin)/delta)
+        min_y = int((bbox.YMin - gbbox.YMin)/delta)
+        min_z = int((bbox.ZMin - gbbox.ZMin)/delta)
+        # find the voxel that contains the bbox max point
+        # (if larger than the voxelSpace, set to voxelSpace max dim,
+        # we already verified that 'bbox' fits into 'gbbox')
+        vs_size = voxelSpace.shape
+        max_x = min(int((bbox.XMax - gbbox.XMin)/delta), vs_size[0]-1)
+        max_y = min(int((bbox.YMax - gbbox.YMin)/delta), vs_size[1]-1)
+        max_z = min(int((bbox.ZMax - gbbox.ZMin)/delta), vs_size[2]-1)
+        # get the base point
+        vbase = Vector(gbbox.XMin + min_x * delta, gbbox.YMin + min_y * delta, gbbox.ZMin + min_z * delta)
+        # now get a sub-tensor out of the voxel space, containing the obj.Shape; but make it one (empty) voxel
+        # larger in every direction (that's the '+2': one voxel in the - direction, one in the +),
+        # so we can check if the object shape span up to the border
+        dim_x = max_x+1-min_x
+        dim_y = max_y+1-min_y
+        dim_z = max_z+1-min_z
+        # create the sub-tensor
+        voxSubSpace = np.full((dim_x+2,dim_y+2,dim_z+2),0,np.int32)
+        # copy the sub-tensor out of the full voxel space, after selecting the elements
+        # corresponding to 'condIndex' and converting (casting with astype() )
+        # to a matrix composed only of zeros and ones (True -> 1, False -> 0)
+        voxSubSpace[1:dim_x+1,1:dim_y+1,1:dim_z+1] = (voxelSpace[min_x:max_x+1,min_y:max_y+1,min_z:max_z+1] == condIndex).astype(np.int8)
+        # now we must find the boundaries in the three x,y,z directions. We differentiate.
+        # start from dx
+        diff = voxSubSpace[1:dim_x+2,:,:] - voxSubSpace[0:dim_x+1,:,:]
+        # and extract the non-zero elements positions
+        voxelIndices = [ [step_x,step_y,step_z] for step_x in range(0,dim_x+1) for step_y in range(0,dim_y+2) for step_z in range(0,dim_z+2) if diff[step_x,step_y,step_z] != 0]
+        # cube x side vertex points
+        vertex = [Vector(0,0,0), Vector(0,0,delta), Vector(0,delta,delta), Vector(0,delta,0)]
+        # now we can create the faces orthogonal to the current direction
+        for index in voxelIndices:
+            # calculate the base point of the vector pointed to by 'index' (remark: 'index' is not the index
+            # of the voxel, but of the surface between two voxels, for the direction along which we are operating)
+            vbaseRel = vbase + Vector(index[0]*delta,(index[1]-1)*delta,(index[2]-1)*delta)
+            # create the face
+            # calculate the vertexes
+            v11 = vbaseRel + vertex[0]
+            v12 = vbaseRel + vertex[1]
+            v13 = vbaseRel + vertex[2]
+            v14 = vbaseRel + vertex[3]
+            # now make the face
+            poly = Part.makePolygon( [v11,v12,v13,v14,v11])
+            face = Part.Face(poly)
+            surfList.append(face)
+        # then dy
+        diff = voxSubSpace[:,1:dim_y+2,:] - voxSubSpace[:,0:dim_y+1,:]
+        # and extract the non-zero elements positions
+        voxelIndices = [ [step_x,step_y,step_z] for step_x in range(0,dim_x+2) for step_y in range(0,dim_y+1) for step_z in range(0,dim_z+2) if diff[step_x,step_y,step_z] != 0]
+        # cube y side vertex points
+        vertex = [Vector(0,0,0), Vector(delta,0,0), Vector(delta,0,delta), Vector(0,0,delta)]
+        # now we can create the faces orthogonal to the current direction
+        for index in voxelIndices:
+            # calculate the base point of the vector pointed to by 'index' (remark: 'index' is not the index
+            # of the voxel, but of the surface between two voxels, for the direction along which we are operating)
+            vbaseRel = vbase + Vector((index[0]-1)*delta,index[1]*delta,(index[2]-1)*delta)
+            # create the face
+            # calculate the vertexes
+            v11 = vbaseRel + vertex[0]
+            v12 = vbaseRel + vertex[1]
+            v13 = vbaseRel + vertex[2]
+            v14 = vbaseRel + vertex[3]
+            # now make the face
+            poly = Part.makePolygon( [v11,v12,v13,v14,v11])
+            face = Part.Face(poly)
+            surfList.append(face)
+        # then dz
+        diff = voxSubSpace[:,:,1:dim_z+2] - voxSubSpace[:,:,0:dim_z+1]
+        # and extract the non-zero elements positions
+        voxelIndices = [ [step_x,step_y,step_z] for step_x in range(0,dim_x+2) for step_y in range(0,dim_y+2) for step_z in range(0,dim_z+1) if diff[step_x,step_y,step_z] != 0]
+        # cube z side vertex points
+        vertex = [Vector(0,0,0), Vector(0,delta,0), Vector(delta,delta,0), Vector(delta,0,0)]
+        # now we can create the faces orthogonal to the current direction
+        for index in voxelIndices:
+            # calculate the base point of the vector pointed to by 'index' (remark: 'index' is not the index
+            # of the voxel, but of the surface between two voxels, for the direction along which we are operating)
+            vbaseRel = vbase + Vector((index[0]-1)*delta,(index[1]-1)*delta,index[2]*delta)
+            # create the face
+            # calculate the vertexes
+            v11 = vbaseRel + vertex[0]
+            v12 = vbaseRel + vertex[1]
+            v13 = vbaseRel + vertex[2]
+            v14 = vbaseRel + vertex[3]
+            # now make the face
+            poly = Part.makePolygon( [v11,v12,v13,v14,v11])
+            face = Part.Face(poly)
+            surfList.append(face)
+        #progBar.stop()
+        FreeCAD.Console.PrintMessage(translate("EM","Voxelization of the shell completed.\n"))
+        # create a shell. Does not need to be solid.
+        objShell = Part.makeShell(surfList)
+        return objShell
+
+    def createVoxelShellFastCoin(self,obj,condIndex,gbbox,delta,voxelSpace=None):
+        ''' Creates a shell composed by the external faces of a voxelized object.
+
+            'obj' is the object whose shell must be created
+            'condIndex' (int16) is the index of the object. It defines the object conductivity.
+            'gbbox' (FreeCAD.BoundBox) is the overall bounding box
+            'delta' is the voxels size length
+            'voxelSpace' (Numpy 3D array) is the voxel tensor of the overall space
+
+            This version uses a direct coin3d / pivy representation of the VHConductor
+            boundaries ('shell'), and calculates the VHConductor
+            boundaries by finite differences over the voxel conductor space,
+            for speed in Python.
+
+            Remark: the VHConductor must have already been voxelized
+    '''
+        if voxelSpace is None:
+            return None
+        if not hasattr(obj,"Shape"):
+            return None
+        if self.Object.isVoxelized == False:
+            return None
+        self.shapePoints = []
+        # get the object's bbox
+        bbox = obj.Shape.BoundBox
+        if not gbbox.isInside(bbox):
+            FreeCAD.Console.PrintError(translate("EM","Conductor bounding box is larger than the global bounding box. Cannot voxelize conductor shell.\n"))
+            return
+        # now must find the voxel set that contains the object bounding box
+        # find the voxel that contains the bbox min point
+        min_x = int((bbox.XMin - gbbox.XMin)/delta)
+        min_y = int((bbox.YMin - gbbox.YMin)/delta)
+        min_z = int((bbox.ZMin - gbbox.ZMin)/delta)
+        # find the voxel that contains the bbox max point
+        # (if larger than the voxelSpace, set to voxelSpace max dim,
+        # we already verified that 'bbox' fits into 'gbbox')
+        vs_size = voxelSpace.shape
+        max_x = min(int((bbox.XMax - gbbox.XMin)/delta), vs_size[0]-1)
+        max_y = min(int((bbox.YMax - gbbox.YMin)/delta), vs_size[1]-1)
+        max_z = min(int((bbox.ZMax - gbbox.ZMin)/delta), vs_size[2]-1)
+        # get the base point
+        vbase = Vector(gbbox.XMin + min_x * delta, gbbox.YMin + min_y * delta, gbbox.ZMin + min_z * delta)
+        # now get a sub-tensor out of the voxel space, containing the obj.Shape; but make it one (empty) voxel
+        # larger in every direction (that's the '+2': one voxel in the - direction, one in the +),
+        # so we can check if the object shape span up to the border
+        dim_x = max_x+1-min_x
+        dim_y = max_y+1-min_y
+        dim_z = max_z+1-min_z
+        # create the sub-tensor
+        voxSubSpace = np.full((dim_x+2,dim_y+2,dim_z+2),0,np.int32)
+        # copy the sub-tensor out of the full voxel space, after selecting the elements
+        # corresponding to 'condIndex' and converting (casting with astype() )
+        # to a matrix composed only of zeros and ones (True -> 1, False -> 0)
+        voxSubSpace[1:dim_x+1,1:dim_y+1,1:dim_z+1] = (voxelSpace[min_x:max_x+1,min_y:max_y+1,min_z:max_z+1] == condIndex).astype(np.int8)
+        # now we must find the boundaries in the three x,y,z directions. We differentiate.
+        # start from dx
+        diff = voxSubSpace[1:dim_x+2,:,:] - voxSubSpace[0:dim_x+1,:,:]
+        # and extract the non-zero elements positions
+        voxelIndices = [ [step_x,step_y,step_z] for step_x in range(0,dim_x+1) for step_y in range(0,dim_y+2) for step_z in range(0,dim_z+2) if diff[step_x,step_y,step_z] != 0]
+        # cube x side vertex points
+        vertex = [Vector(0,0,0), Vector(0,0,delta), Vector(0,delta,delta), Vector(0,delta,0)]
+        # now we can create the faces orthogonal to the current direction
+        for index in voxelIndices:
+            # calculate the base point of the vector pointed to by 'index' (remark: 'index' is not the index
+            # of the voxel, but of the surface between two voxels, for the direction along which we are operating)
+            vbaseRel = vbase + Vector(index[0]*delta,(index[1]-1)*delta,(index[2]-1)*delta)
+            # create the face
+            # calculate the vertexes
+            v11 = vbaseRel + vertex[0]
+            v12 = vbaseRel + vertex[1]
+            v13 = vbaseRel + vertex[2]
+            v14 = vbaseRel + vertex[3]
+            # now make the face
+            self.shapePoints.extend([v11,v12,v13,v14])
+        # then dy
+        diff = voxSubSpace[:,1:dim_y+2,:] - voxSubSpace[:,0:dim_y+1,:]
+        # and extract the non-zero elements positions
+        voxelIndices = [ [step_x,step_y,step_z] for step_x in range(0,dim_x+2) for step_y in range(0,dim_y+1) for step_z in range(0,dim_z+2) if diff[step_x,step_y,step_z] != 0]
+        # cube y side vertex points
+        vertex = [Vector(0,0,0), Vector(delta,0,0), Vector(delta,0,delta), Vector(0,0,delta)]
+        # now we can create the faces orthogonal to the current direction
+        for index in voxelIndices:
+            # calculate the base point of the vector pointed to by 'index' (remark: 'index' is not the index
+            # of the voxel, but of the surface between two voxels, for the direction along which we are operating)
+            vbaseRel = vbase + Vector((index[0]-1)*delta,index[1]*delta,(index[2]-1)*delta)
+            # create the face
+            # calculate the vertexes
+            v11 = vbaseRel + vertex[0]
+            v12 = vbaseRel + vertex[1]
+            v13 = vbaseRel + vertex[2]
+            v14 = vbaseRel + vertex[3]
+            # now make the face
+            self.shapePoints.extend([v11,v12,v13,v14])
+        # then dz
+        diff = voxSubSpace[:,:,1:dim_z+2] - voxSubSpace[:,:,0:dim_z+1]
+        # and extract the non-zero elements positions
+        voxelIndices = [ [step_x,step_y,step_z] for step_x in range(0,dim_x+2) for step_y in range(0,dim_y+2) for step_z in range(0,dim_z+1) if diff[step_x,step_y,step_z] != 0]
+        # cube z side vertex points
+        vertex = [Vector(0,0,0), Vector(0,delta,0), Vector(delta,delta,0), Vector(delta,0,0)]
+        # now we can create the faces orthogonal to the current direction
+        for index in voxelIndices:
+            # calculate the base point of the vector pointed to by 'index' (remark: 'index' is not the index
+            # of the voxel, but of the surface between two voxels, for the direction along which we are operating)
+            vbaseRel = vbase + Vector((index[0]-1)*delta,(index[1]-1)*delta,index[2]*delta)
+            # create the face
+            # calculate the vertexes
+            v11 = vbaseRel + vertex[0]
+            v12 = vbaseRel + vertex[1]
+            v13 = vbaseRel + vertex[2]
+            v14 = vbaseRel + vertex[3]
+            # now make the face
+            self.shapePoints.extend([v11,v12,v13,v14])
+        #progBar.stop()
+        #FreeCAD.Console.PrintMessage(translate("EM","Voxelization of the shell completed.\n"))
+        return True
+        
+    def voxelizeConductor(self):
+        ''' Voxelize the Base (solid) object. The function will modify the 'voxelSpace'
+            by marking with 'CondIndex' all the voxels that sample the Base object
+            as internal.
+    '''
+        if self.Object.Base is None:
+            return
+        if not hasattr(self.Object.Base,"Shape"):
+            return
+        # get the VHSolver object
+        solver = getVHSolver()
+        if solver is None:
+             return
+        FreeCAD.Console.PrintMessage(translate("EM","Starting voxelization of conductor ") + self.Object.Label + "...\n")
+        # get global parameters from the VHSolver object
+        gbbox = solver.Proxy.getGlobalBBox()
+        delta = solver.Proxy.getDelta()
+        voxelSpace = solver.Proxy.getVoxelSpace()
+        if voxelSpace is None:
+            FreeCAD.Console.PrintWarning(translate("EM","VoxelSpace not valid, cannot voxelize conductor\n"))
+            return
+        # get this object bbox
+        bbox = self.Object.Base.Shape.BoundBox
+        if not gbbox.isInside(bbox):
+            FreeCAD.Console.PrintError(translate("EM","Internal error: conductor bounding box is larger than the global bounding box. Cannot voxelize conductor.\n"))
+            return
+        # first of all, must remove all previous instances of the conductor in the voxel space
+        voxelSpace[voxelSpace==self.Object.CondIndex] = 0
+        # now must find the voxel set that contains the object bounding box
+        # find the voxel that contains the bbox min point
+        min_x = int((bbox.XMin - gbbox.XMin)/delta)
+        min_y = int((bbox.YMin - gbbox.YMin)/delta)
+        min_z = int((bbox.ZMin - gbbox.ZMin)/delta)
+        # find the voxel that contains the bbox max point
+        # (if larger than the voxelSpace, set to voxelSpace max dim,
+        # we already verified that 'bbox' fits into 'gbbox')
+        vs_size = voxelSpace.shape
+        max_x = min(int((bbox.XMax - gbbox.XMin)/delta), vs_size[0]-1)
+        max_y = min(int((bbox.YMax - gbbox.YMin)/delta), vs_size[1]-1)
+        max_z = min(int((bbox.ZMax - gbbox.ZMin)/delta), vs_size[2]-1)
+        # if the Base object is a Part::Box, just mark all the voxels
+        # inside the bounding box as belonging to the conductor
+        if self.Object.Base.TypeId == "Part::Box":
+            voxelSpace[min_x:max_x,min_y:max_y,min_z:max_z] = self.Object.CondIndex
+        else:
+            # and now find which voxel is inside the object 'self.Object.Base',
+            # sampling based on the voxel centers
+            voxelIndices = [ (step_x,step_y,step_z) for step_x in range(min_x,max_x+1)
+                                for step_y in range(min_y,max_y+1)
+                                for step_z in range(min_z,max_z+1)
+                                if self.Object.Base.Shape.isInside(Vector(gbbox.XMin + step_x * delta + delta/2.0,
+                                gbbox.YMin + step_y * delta + delta/2.0,
+                                gbbox.ZMin + step_z * delta + delta/2.0),0.0,True)]
+            # mark the relevant voxels with the 'CondIndex'
+            # note that as Python3 zip() returns an iterator, need to build the list of indices explicitly,
+            # but then we need to move this to a tuple to avoid a Python3 warning
+            voxelSpace[tuple([x for x in zip(*voxelIndices)])] = self.Object.CondIndex
+        # flag as voxelized
+        self.Object.isVoxelized = True
+        # if just voxelized, cannot show voxeld; and if there was an old shell representing
+        # the previoius voxelization, must clear it
+        self.Object.ShowVoxels = False
+        FreeCAD.Console.PrintMessage(translate("EM","Voxelization of the conductor completed.\n"))
+
+    def flagVoxelizationInvalid(self):
+        ''' Flags the voxelization as invalid
+    '''
+        self.Object.isVoxelized = False
+        self.Object.ShowVoxels = False
+
+    def getBaseObj(self):
+        ''' Retrieves the Base object.
+
+            Returns the Base object.
+    '''
+        return self.Object.Base
+
+    def getBBox(self):
+        ''' Retrieves the bounding box containing the base objects
+
+            Returns a FreeCAD::BoundBox
+    '''
+        bbox = FreeCAD.BoundBox()
+        if self.Object.Base is not None:
+            if hasattr(self.Object.Base,"Shape"):
+                bbox = self.Object.Base.Shape.BoundBox
+        return bbox
+
+    def getCondIndex(self):
+        ''' Retrieves the conductor index.
+
+            Returns the int16 conductor index.
+    '''
+        return self.Object.CondIndex
+
+    def setVoxelState(self,isVoxelized):
+        ''' Sets the voxelization state.
+    '''
+        self.Object.isVoxelized = isVoxelized
+
+    def serialize(self,fid,isSupercond):
+        ''' Serialize the object to the 'fid' file descriptor
+
+        'fid' is the file descriptor
+        'isSupercond' is a boolean indicating if the input file must contain
+            superconductor lambda values (even if for some conductors this may be zero)
+    '''
+        if self.Object.isVoxelized == True:
+            solver = getVHSolver()
+            if solver is None:
+                 return
+            # get global parameters from the VHSolver object
+            gbbox = solver.Proxy.getGlobalBBox()
+            delta = solver.Proxy.getDelta()
+            voxelSpace = solver.Proxy.getVoxelSpace()
+            # get this object bbox
+            bbox = self.Object.Base.Shape.BoundBox
+            if not gbbox.isInside(bbox):
+                FreeCAD.Console.PrintError(translate("EM","Conductor bounding box is larger than the global bounding box. Cannot serialize VHConductor.\n"))
+                return
+            # now must find the voxel set that contains the object bounding box
+            # find the voxel that contains the bbox min point
+            min_x = int((bbox.XMin - gbbox.XMin)/delta)
+            min_y = int((bbox.YMin - gbbox.YMin)/delta)
+            min_z = int((bbox.ZMin - gbbox.ZMin)/delta)
+            # find the voxel that contains the bbox max point
+            # (if larger than the voxelSpace, set to voxelSpace max dim,
+            # we already verified that 'bbox' fits into 'gbbox')
+            vs_size = voxelSpace.shape
+            max_x = min(int((bbox.XMax - gbbox.XMin)/delta), vs_size[0]-1)
+            max_y = min(int((bbox.YMax - gbbox.YMin)/delta), vs_size[1]-1)
+            max_z = min(int((bbox.ZMax - gbbox.ZMin)/delta), vs_size[2]-1)
+            # and now find which voxel belongs to this VHConductor
+            voxCoords = np.argwhere(voxelSpace[min_x:max_x+1, min_y:max_y+1, min_z:max_z+1]==self.Object.CondIndex)
+            # remark: VoxHenry voxel tensor is 1-based, not 0-based. Must add 1
+            voxCoords = voxCoords + 1
+            # and add the base offset
+            voxCoords[:,0] = voxCoords[:,0]+min_x
+            voxCoords[:,1] = voxCoords[:,1]+min_y
+            voxCoords[:,2] = voxCoords[:,2]+min_z
+            # now must add the information about the 'CondIndex' value:
+            voxCoordsSize = voxCoords.shape
+            # check if we must output lambda values or not
+            if isSupercond:
+                # first create a new matrix with an additional column full of 'Sigma'
+                voxCoordsAndCond = np.full((voxCoordsSize[0],voxCoordsSize[1]+2),self.Object.Sigma,np.float64)
+                # add the lambda values (note that since there is one column only, this is treated as an array in numpy, i.e. row-like)
+                voxCoordsAndCond[:,-1] = np.full(voxCoordsSize[0],self.Object.Lambda.getValueAs('m'),np.float64)
+                # then copy in the first 2 columns the voxCoords
+                # REMARK: this is now a float64 array! Cannot contain int64 values without loss of precision
+                # but up to 32 bits this should be ok
+                voxCoordsAndCond[:,:-2] = voxCoords
+                # finally output the voxels
+                np.savetxt(fid, voxCoordsAndCond, fmt="V %d %d %d %g %g")
+            else:
+                # first create a new matrix with an additional column full of 'Sigma'
+                voxCoordsAndCond = np.full((voxCoordsSize[0],voxCoordsSize[1]+1),self.Object.Sigma,np.float64)
+                # then copy in the first 2 columns the voxCoords
+                # REMARK: this is now a float64 array! Cannot contain int64 values without loss of precision
+                # but up to 32 bits this should be ok
+                voxCoordsAndCond[:,:-1] = voxCoords
+                # finally output the voxels
+                np.savetxt(fid, voxCoordsAndCond, fmt="V %d %d %d %g")
+        else:
+            FreeCAD.Console.PrintWarning(translate("EM","VHConductor object not voxelized, cannot serialize ") + str(self.Object.Label) + "\n")
+
+    def __getstate__(self):
+        # JSON does not understand FreeCAD.Vector, so need to convert to tuples
+        shapePointsJSON = [(x[0],x[1],x[2]) for x in self.shapePoints]
+        dictForJSON = {'sp':shapePointsJSON,'type':self.Type}
+        #FreeCAD.Console.PrintMessage("Save\n"+str(dictForJSON)+"\n") #debug
+        return dictForJSON
+
+    def __setstate__(self,dictForJSON):
+        if dictForJSON:
+            #FreeCAD.Console.PrintMessage("Load\n"+str(dictForJSON)+"\n") #debug
+            # no need to convert back to FreeCAD.Vectors, 'shapePoints' can also be tuples
+            self.shapePoints = dictForJSON['sp']
+            self.Type = dictForJSON['type']
+
+class _ViewProviderVHConductor:
+    def __init__(self, vobj):
+        ''' Set this object to the proxy object of the actual view provider '''
+        vobj.Proxy = self
+        self.VObject = vobj
+        self.Object = vobj.Object
+
+    def attach(self, vobj):
+        ''' Setup the scene sub-graph of the view provider, this method is mandatory '''
+        #FreeCAD.Console.PrintMessage("ViewProvider attach()\n") # debug
+        # on restore, self.Object is not there anymore (JSON does not serialize complex objects
+        # members of the class, so __getstate__() and __setstate__() skip them);
+        # so we must "re-attach" (re-create) the 'self.Object'
+        self.VObject = vobj
+        self.Object = vobj.Object
+        # actual representation
+        self.switch = coin.SoSwitch()
+        self.hints = coin.SoShapeHints()
+        self.style1 = coin.SoDrawStyle()
+        self.style2 = coin.SoDrawStyle()
+        self.material = coin.SoMaterial()
+        self.linecolor = coin.SoBaseColor()
+        self.data = coin.SoCoordinate3()
+        self.face = coin.SoFaceSet()
+        # init
+        # A shape hints tells the ordering of polygons.
+        # This ensures double-sided lighting.
+        self.hints.vertexOrdering = coin.SoShapeHints.COUNTERCLOCKWISE
+        self.hints.faceType = coin.SoShapeHints.CONVEX
+        # init styles
+        self.style1.style = coin.SoDrawStyle.FILLED
+        self.style2.style = coin.SoDrawStyle.LINES
+        self.style2.lineWidth = self.VObject.LineWidth
+        # init color
+        self.material.diffuseColor.setValue(self.VObject.ShapeColor[0],self.VObject.ShapeColor[1],self.VObject.ShapeColor[2])
+        self.material.transparency = self.VObject.Transparency/100.0
+        self.linecolor.rgb.setValue(self.VObject.LineColor[0],self.VObject.LineColor[1],self.VObject.LineColor[2])
+        # instructs to visit the first child (this is used to toggle visiblity)
+        self.switch.whichChild = coin.SO_SWITCH_ALL
+        #  scene
+        #sep = coin.SoSeparator()
+        # not using a separator, but a FreeCAD Selection node
+        sep = coin.SoType.fromName("SoFCSelection").createInstance()
+        sep.documentName.setValue(self.Object.Document.Name)
+        sep.objectName.setValue(self.Object.Name)
+        sep.subElementName.setValue("Face")
+        # now adding the common children
+        sep.addChild(self.hints)
+        sep.addChild(self.data)
+        sep.addChild(self.switch)
+        # and finally the two groups, the first is the contour lines,
+        # the second is the filled faces, so we can switch between
+        # "Flat Lines", "Shaded" and "Wireframe". Note: not implementing "Points"
+        group0Line = coin.SoGroup()
+        self.switch.addChild(group0Line)
+        group0Line.addChild(self.style2)
+        group0Line.addChild(self.linecolor)
+        group0Line.addChild(self.face)
+        group1Face = coin.SoGroup()
+        self.switch.addChild(group1Face)
+        group1Face.addChild(self.material)
+        group1Face.addChild(self.style1)
+        group1Face.addChild(self.face)
+        self.VObject.RootNode.addChild(sep)
+        #FreeCAD.Console.PrintMessage("ViewProvider attach() completed\n")
+        return
+         
+    def updateData(self, fp, prop):
+        ''' If a property of the data object has changed we have the chance to handle this here 
+            'fp' is the handled feature (the object)
+            'prop' is the name of the property that has changed
+    '''
+        #FreeCAD.Console.PrintMessage("ViewProvider updateData(),  property: " + str(prop) + "\n") # debug
+        if prop == "Shape":
+            numpoints = len(self.Object.Proxy.shapePoints)
+            # this can be used to reset the number of points to the value actually needed
+            # (e.g. shorten the array, or pre-allocate it). However setValue() will automatically
+            # increase the array size if needed, and will NOT shorten it if less values are inserted
+            # This is less memory efficient, but faster; and in using the points in the SoFaceSet,
+            # we specify how many points (vertices) we want out of the total array, so no issue
+            # if the array is longer
+            #self.data.point.setNum(numpoints)
+            self.data.point.setValues(0,numpoints,self.Object.Proxy.shapePoints)
+            # 'numvertices' contains the number of vertices used for each face.
+            # Here all faces are quadrilaterals, so this is a long array of number '4's
+            numvertices = [4 for i in range(int(numpoints/4))]
+            # set the number of vertices per each face, for a total of len(numvertices) faces, starting from 0
+            # but must first delete all the old values, otherwise the remaining panels with vertices from
+            # 'numvertices+1' will still be shown
+            self.face.numVertices.deleteValues(0,-1)
+            self.face.numVertices.setValues(0,len(numvertices),numvertices)
+            #FreeCAD.Console.PrintMessage("numpoints " + str(numpoints) + "; numvertices " + str(numvertices) + "\n") # debug
+            #FreeCAD.Console.PrintMessage("self.Object.Proxy.shapePoints " + str(self.Object.Proxy.shapePoints) + "\n") # debug
+            #FreeCAD.Console.PrintMessage("self.data.point " + str(self.data.point.get()) + "\n") # debug
+            #FreeCAD.Console.PrintMessage("updateData() shape!\n") # debug
+        return
+       
+#    def getDisplayModes(self,obj):
+#        '''Return a list of display modes.'''
+#        modes=[]
+#        modes.append("Shaded")
+#        modes.append("Wireframe")
+#        return modes
+
+    def onChanged(self, vp, prop):
+        ''' If the 'prop' property changed for the ViewProvider 'vp' '''
+        #FreeCAD.Console.PrintMessage("ViewProvider onChanged(), property: " + str(prop) + "\n") # debug
+        if prop == "ShapeColor":
+            #self.color.rgb.setValue(self.VObject.ShapeColor[0],self.VObject.ShapeColor[1],self.VObject.ShapeColor[2])
+            self.material.diffuseColor.setValue(self.VObject.ShapeColor[0],self.VObject.ShapeColor[1],self.VObject.ShapeColor[2])
+        if prop == "Visibility" or prop=="DisplayMode":
+            if not vp.Visibility:
+                self.switch.whichChild = coin.SO_SWITCH_NONE
+            else:
+                if self.VObject.DisplayMode == "Wireframe":
+                    self.switch.whichChild = 0
+                elif self.VObject.DisplayMode == "Shaded":
+                    self.switch.whichChild = 1
+                else:
+                    self.switch.whichChild = coin.SO_SWITCH_ALL
+        if prop == "LineColor":
+            self.linecolor.rgb.setValue(self.VObject.LineColor[0],self.VObject.LineColor[1],self.VObject.LineColor[2])
+        if prop == "LineWidth":
+            self.style2.lineWidth = self.VObject.LineWidth
+        if prop == "Transparency":
+            self.material.transparency = self.VObject.Transparency/100.0
+        
+    def getDefaultDisplayMode(self):
+        ''' Return the name of the default display mode. It must be defined in getDisplayModes. '''
+        return "Flat Lines"
+
+#    def setDisplayMode(self,mode):
+#        return mode
+
+    def claimChildren(self):
+        ''' Used to place other objects as children in the tree'''
+        c = []
+        if hasattr(self,"Object"):
+            if hasattr(self.Object,"Base"):
+                c.append(self.Object.Base)
+        return c
+
+    def getIcon(self):
+        ''' Return the icon which will appear in the tree view. This method is optional
+        and if not defined a default icon is shown.
+        '''
+        return os.path.join(iconPath, 'EM_VHConductor.svg')
+
+    def __getstate__(self):
+        return None
+
+    def __setstate__(self,state):
+        return None
+
+class _CommandVHConductor:
+    ''' The EM VoxHenry Conductor (VHConductor) command definition
+'''
+    def GetResources(self):
+        return {'Pixmap'  : os.path.join(iconPath, 'EM_VHConductor.svg') ,
+                'MenuText': QT_TRANSLATE_NOOP("EM_VHConductor","VHConductor"),
+                'Accel': "E, C",
+                'ToolTip': QT_TRANSLATE_NOOP("EM_VHConductor","Creates a VoxHenry Conductor object (voxelized 3D object) from a selected solid base object")}
+
+    def IsActive(self):
+        return not FreeCAD.ActiveDocument is None
+
+    def Activated(self):
+        # preferences
+        #p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/EM")
+        #self.Width = p.GetFloat("Width",200)
+        # get the selected object(s)
+        selection = FreeCADGui.Selection.getSelectionEx()
+        # if selection is not empty
+        done = False
+        for selobj in selection:
+            # automatic mode
+            if selobj.Object.isDerivedFrom("Part::Feature"):
+                FreeCAD.ActiveDocument.openTransaction(translate("EM","Create VHConductor"))
+                FreeCADGui.addModule("EM")
+                FreeCADGui.doCommand('obj=EM.makeVHConductor(FreeCAD.ActiveDocument.'+selobj.Object.Name+')')
+                # autogrouping, for later on
+                #FreeCADGui.addModule("Draft")
+                #FreeCADGui.doCommand("Draft.autogroup(obj)")
+                FreeCAD.ActiveDocument.commitTransaction()
+                FreeCAD.ActiveDocument.recompute()
+                # this is not a mistake. The double recompute() is needed to show the new FHNode object
+                # that have been created by the first execute(), called upon the first recompute()
+                FreeCAD.ActiveDocument.recompute()
+                done = True
+        if done == False:
+            FreeCAD.Console.PrintWarning(translate("EM","No valid object found in the selection for the creation of a VHConductor. Nothing done."))
+
+class _CommandVHCondPortVoxelize:
+    ''' The EM VoxHenry conductor (VHConductor) and port (VHPort) voxelize command definition
+'''
+    def GetResources(self):
+        return {'Pixmap'  : os.path.join(iconPath, 'EM_VHCondPortVoxelize.svg') ,
+                'MenuText': QT_TRANSLATE_NOOP("EM_VHCondPortVoxelize","VHCondPortVoxelize"),
+                'Accel': "E, V",
+                'ToolTip': QT_TRANSLATE_NOOP("EM_VHCondPortVoxelize","Voxelize the selected VHConductor(s) and VHPort(s)")}
+
+    def IsActive(self):
+        return not FreeCAD.ActiveDocument is None
+
+    def Activated(self):
+        # preferences
+        #p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/EM")
+        #self.Width = p.GetFloat("Width",200)
+        # get the selected object(s)
+        selection = FreeCADGui.Selection.getSelectionEx()
+        conds = []
+        ports = []
+        # if selection is not empty
+        for selobj in selection:
+            # screen the VHConductors and VHPorts
+            objType = Draft.getType(selobj.Object)
+            if objType == "VHConductor":
+                conds.append(selobj.Object)
+            elif objType == "VHPort":
+                ports.append(selobj.Object)
+        if len(conds) > 0 or len(ports) > 0:
+            FreeCAD.ActiveDocument.openTransaction(translate("EM","Voxelize VHConductors and VHPorts"))
+            FreeCADGui.addModule("EM")
+            for cond in conds:
+                FreeCADGui.doCommand('FreeCAD.ActiveDocument.'+cond.Name+'.Proxy.voxelizeConductor()')
+            for port in ports:
+                FreeCADGui.doCommand('FreeCAD.ActiveDocument.'+port.Name+'.Proxy.voxelizePort()')
+            FreeCAD.ActiveDocument.commitTransaction()
+        # recompute the document (assuming something has changed; otherwise this is dummy)
+        FreeCAD.ActiveDocument.recompute()
+
+if FreeCAD.GuiUp:
+    FreeCADGui.addCommand('EM_VHConductor',_CommandVHConductor())
+    FreeCADGui.addCommand('EM_VHCondPortVoxelize',_CommandVHCondPortVoxelize())

EM_VHInputFile.py

@@ -0,0 +1,175 @@
+#***************************************************************************
+#*                                                                         *
+#*   Copyright (c) 2019                                                    *
+#*   FastFieldSolvers S.R.L., http://www.fastfieldsolvers.com              *
+#*                                                                         *
+#*   This program is free software; you can redistribute it and/or modify  *
+#*   it under the terms of the GNU Lesser General Public License (LGPL)    *
+#*   as published by the Free Software Foundation; either version 2 of     *
+#*   the License, or (at your option) any later version.                   *
+#*   for detail see the LICENCE text file.                                 *
+#*                                                                         *
+#*   This program is distributed in the hope that it will be useful,       *
+#*   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+#*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+#*   GNU Library General Public License for more details.                  *
+#*                                                                         *
+#*   You should have received a copy of the GNU Library General Public     *
+#*   License along with this program; if not, write to the Free Software   *
+#*   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+#*   USA                                                                   *
+#*                                                                         *
+#***************************************************************************
+
+
+__title__="FreeCAD E.M. Workbench VoxHenry create input file command"
+__author__ = "FastFieldSolvers S.R.L."
+__url__ = "http://www.fastfieldsolvers.com"
+
+import FreeCAD, FreeCADGui, Mesh, Part, MeshPart, Draft, DraftGeomUtils, os
+from FreeCAD import Vector
+from PySide import QtCore, QtGui
+
+if FreeCAD.GuiUp:
+    import FreeCADGui
+    from PySide import QtCore, QtGui
+    from DraftTools import translate
+    from PySide.QtCore import QT_TRANSLATE_NOOP
+else:
+    # \cond
+    def translate(ctxt,txt, utf8_decode=False):
+        return txt
+    def QT_TRANSLATE_NOOP(ctxt,txt):
+        return txt
+    # \endcond
+
+__dir__ = os.path.dirname(__file__)
+iconPath = os.path.join( __dir__, 'Resources' )
+
+def createVHInputFile(doc=None,filename=None,folder=None):
+    '''Outputs a VoxHenry input file based on the active document geometry
+    
+       'doc' is the Document object that must contain at least one 
+            EM_VHSolver object and the relevant geometry.
+            If no 'doc' is given, the active document is used, if any.
+       'filename' is the filename to use. If not passed as an argument,
+            the 'Filename' property of the VHSolver object contained in the document
+            will be used. If the "Filename" string in the VHSolver object is empty,
+            the function builds a filename concatenating the document name
+            with the default extension EMVHSOLVER_DEF_FILENAME.
+            Whatever the name, if a file with the same name exists in the target
+            folder, the user is prompted to know if he/she wants to overwrite it.
+        'folder' is the folder where the file will be stored. If not passed
+            as an argument, the 'Folder' property of the VHSolver object
+            contained in the document will be used. If the 'Folder' string
+            in the VHSolver object is empty, the function defaults to the
+            user's home path (e.g. in Windows "C:\Documents and Settings\
+            username\My Documents", in Linux "/home/username")
+    
+    Example:
+         createVHInputFile()
+'''
+    if not doc:
+        doc = FreeCAD.ActiveDocument
+    if not doc:
+        FreeCAD.Console.PrintWarning(translate("EM","No active document available. Aborting."))
+        return
+    # get the solver object, if any
+    solver = [obj for obj in doc.Objects if Draft.getType(obj) == "VHSolver"]
+    if solver == []:
+        # error
+        FreeCAD.Console.PrintWarning(translate("EM","VHSolver object not found in the document. Aborting."))
+        return
+    else:
+        if len(solver) > 1:
+            FreeCAD.Console.PrintWarning(translate("EM","More than one VHSolver object found in the document. Using the first one."))
+        solver = solver[0]
+    if not filename:
+        # if 'filename' was not passed as an argument, retrieve it from the 'solver' object
+        # (this should be the standard way)
+        if solver.Filename == "":
+            # build a filename concatenating the document name
+            solver.Filename = doc.Name + EM.EMVHSOLVER_DEF_FILENAME
+        filename = solver.Filename
+    else:
+        # otherwise, if the user passed a filename to the function, update it in the 'solver' object
+        solver.Filename = filename
+    if not folder:
+        # if 'folder' was not passed as an argument, retrieve it from the 'solver' object
+        # (this should be the standard way)
+        if solver.Folder == "":
+            # if not specified, default to the user's home path
+            # (e.g. in Windows "C:\Documents and Settings\username\My Documents", in Linux "/home/username")
+            solver.Folder = FreeCAD.ConfigGet("UserHomePath")
+        folder = solver.Folder
+    if not os.path.isdir(folder):
+        # if 'folder' does not exists, create it
+        os.mkdir(folder)
+    # check if exists
+    if os.path.isfile(folder + os.sep + filename):
+        # filename already exists! Check if overwrite
+        diag = QtGui.QMessageBox()
+        diag.setText("File '" + str(filename) + "' exists in the folder '" + str(folder) + "'")
+        diag.setInformativeText("Do you want to overwrite?")
+        diag.setStandardButtons(QtGui.QMessageBox.Cancel | QtGui.QMessageBox.Ok)
+        ret = diag.exec_()
+        if ret == QtGui.QMessageBox.Cancel:
+            return
+    FreeCAD.Console.PrintMessage(QT_TRANSLATE_NOOP("EM","Exporting to VoxHenry file ") + "'" + folder + os.sep + filename + "'\n")
+    with open(folder + os.sep + filename, 'w') as fid:
+        # serialize the header
+        solver.Proxy.serialize(fid)
+        # check if there are superconductors
+        isSupercond = solver.Proxy.isSupercond()
+        if isSupercond:
+            fid.write("* Specify there are superconductors\n")
+            fid.write("Superconductor\n")
+            fid.write("\n")
+        # now the conductors
+        fid.write("* Voxel list\n")
+        fid.write("* Format is:\n")
+        fid.write("* V <index_x> <index_y> <index_z> <conductivity S/m>\n")
+        fid.write("*\n")
+        fid.write("StartVoxelList\n")
+        conds = [obj for obj in doc.Objects if Draft.getType(obj) == "VHConductor"]
+        for cond in conds:
+            FreeCAD.Console.PrintMessage(QT_TRANSLATE_NOOP("EM","  Exporting conductor ") + "'" + cond.Label + "'\n")
+            cond.Proxy.serialize(fid, isSupercond)
+        fid.write("EndVoxelList\n")
+        fid.write("\n")
+        # then the ports
+        ports = [obj for obj in doc.Objects if Draft.getType(obj) == "VHPort"]
+        if ports:
+            fid.write("* Port nodes list\n")
+            fid.write("* Format is:\n")
+            fid.write("* N <portname> <excitation or ground (P/N)> <voxel_index_x> <voxel_index_y> <voxel_index_z> <node (+z,-z,+x,-x,+y,-y)>\n")
+            fid.write("*\n")
+            for port in ports:
+                port.Proxy.serialize(fid)
+            fid.write("\n")
+    FreeCAD.Console.PrintMessage(QT_TRANSLATE_NOOP("EM","Finished exporting")+"\n")
+
+class _CommandVHInputFile:
+    ''' The EM VoxHenry create input file command definition
+'''
+    def GetResources(self):
+        return {'Pixmap'  : os.path.join(iconPath, 'EM_VHInputFile.svg') ,
+                'MenuText': QT_TRANSLATE_NOOP("EM_VHInputFile","VHInputFile"),
+                'Accel': "E, I",
+                'ToolTip': QT_TRANSLATE_NOOP("EM_VHInputFile","Creates a FastHenry input file")}
+                
+    def IsActive(self):
+        return not FreeCAD.ActiveDocument is None
+
+    def Activated(self):
+        # preferences
+        #p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/EM")
+        #self.Width = p.GetFloat("Width",200)
+        FreeCAD.ActiveDocument.openTransaction(translate("EM","Create a VoxHenry file"))
+        FreeCADGui.addModule("EM")
+        FreeCADGui.doCommand('obj=EM.createVHInputFile(App.ActiveDocument)')
+        FreeCAD.ActiveDocument.commitTransaction()
+        FreeCAD.ActiveDocument.recompute()
+
+if FreeCAD.GuiUp:
+    FreeCADGui.addCommand('EM_VHInputFile',_CommandVHInputFile())

EM_VHPort.py

@@ -0,0 +1,737 @@
+#***************************************************************************
+#*                                                                         *
+#*   Copyright (c) 2019                                                    *
+#*   FastFieldSolvers S.R.L., http://www.fastfieldsolvers.com              *
+#*                                                                         *
+#*   This program is free software; you can redistribute it and/or modify  *
+#*   it under the terms of the GNU Lesser General Public License (LGPL)    *
+#*   as published by the Free Software Foundation; either version 2 of     *
+#*   the License, or (at your option) any later version.                   *
+#*   for detail see the LICENCE text file.                                 *
+#*                                                                         *
+#*   This program is distributed in the hope that it will be useful,       *
+#*   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+#*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+#*   GNU Library General Public License for more details.                  *
+#*                                                                         *
+#*   You should have received a copy of the GNU Library General Public     *
+#*   License along with this program; if not, write to the Free Software   *
+#*   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+#*   USA                                                                   *
+#*                                                                         *
+#***************************************************************************
+
+
+__title__="FreeCAD E.M. Workbench VoxHenry Port Class"
+__author__ = "FastFieldSolvers S.R.L."
+__url__ = "http://www.fastfieldsolvers.com"
+
+# default port colors
+EMVHPORT_DEF_POSPORTCOLOR = (1.0,0.0,0.0)
+EMVHPORT_DEF_NEGPORTCOLOR = (0.0,0.0,0.0)
+EMVHPORT_DEF_LINECOLOR = (0.25, 0.25, 0.25)
+# displacement percentage fraction of the voxel dimension
+EMVHPORT_EPSDELTA = 10.0
+# side strings
+EMVHPORT_SIDESTRS = ['+x', '-x', '+y', '-y', '+z', '-z']
+
+import FreeCAD, FreeCADGui, Part, Draft, DraftGeomUtils, os
+import DraftVecUtils
+from EM_Globals import getVHSolver
+from FreeCAD import Vector
+import time
+from pivy import coin
+
+if FreeCAD.GuiUp:
+    import FreeCADGui
+    from PySide import QtCore, QtGui
+    from DraftTools import translate
+    from PySide.QtCore import QT_TRANSLATE_NOOP
+else:
+    # \cond
+    def translate(ctxt,txt, utf8_decode=False):
+        return txt
+    def QT_TRANSLATE_NOOP(ctxt,txt):
+        return txt
+    # \endcond
+
+__dir__ = os.path.dirname(__file__)
+iconPath = os.path.join( __dir__, 'Resources' )
+
+def makeVHPortFromSel(selection=[]):
+    ''' Creates a VoxHenry Port from the selection
+    
+        'selection' is a selection object (from getSelectionEx() )
+            The selection object must contain at least two faces
+    
+    Example:
+        port = makeVHPortFromSel(FreeCADGui.Selection.getSelectionEx())
+'''
+    port = None
+    # if selection is not empty
+    if len(selection) > 0:
+        real_faces = []
+        # get all the subobjects of the selection (faces, edges, etc.)
+        for selobj in selection:
+            if selobj.HasSubObjects:
+                # screen out the faces
+                for sobj in selobj.SubElementNames:
+                    if "Face" in sobj:
+                        real_faces.append((selobj.Object, (sobj,)))
+                real_faces_len = len(real_faces)
+                # need at least two faces to make a port
+        if real_faces_len > 1:
+            mid = int(real_faces_len / 2)
+            port = makeVHPort(real_faces[0:mid],real_faces[mid:real_faces_len])
+    if port is None:
+       FreeCAD.Console.PrintWarning(translate("EM","No faces selected for the creation of a VHPort (need at least two). Nothing done.")) 
+    return port
+    
+def makeVHPort(posFaces=None,negFaces=None,name='VHPort'):
+    ''' Creates a VoxHenry Port (a set of two voxelized faces, representing the positive and negative contacts)
+    
+        'posFaces' is a list of faces of a 3D solid object that is forming the positive
+            contact of the port. If no 'posFace' is given, the user must assign a list
+            later on, to be able to use this object.
+        'negFaces' is a list of faces of a 3D solid object that is forming the negative
+            contact of the port. If no 'negFace' is given, the user must assign a list
+            later on, to be able to use this object.
+        'name' is the name of the object
+    
+    Example:
+        port = makeVHPort(myPosFaces, myNegFaces)
+'''
+    obj = FreeCAD.ActiveDocument.addObject("Part::FeaturePython", name)
+    obj.Label = translate("EM", name)
+    # this adds the relevant properties to the object 
+    #'obj' (e.g. 'Base' property) making it a _VHPort 
+    _VHPort(obj)
+    # manage ViewProvider object
+    if FreeCAD.GuiUp:
+        _ViewProviderVHPort(obj.ViewObject)
+        # set base ViewObject properties to user-selected values (if any)
+    # check if 'posFaces' contains valid faces
+    real_faces = obj.PosFaces
+    if posFaces != []:
+        # screen out the faces
+        for face in posFaces:
+            if "Face" in face[1][0]:
+                real_faces.append(face)
+        # cannot directly append to 'obj.PosFaces' as this is a PropertyLinkSubList object,
+        # that automatically detect multiple instances of the same Part::Feature,
+        # and merges the sub-object lists (e.g. faces)
+        obj.PosFaces = real_faces
+    # check if 'negFaces' contains valid faces
+    real_faces = obj.NegFaces
+    if negFaces != []:
+        # screen out the faces
+        for face in negFaces:
+            if "Face" in face[1][0]:
+                real_faces.append(face)
+        # cannot directly append to 'obj.PosFaces' as this is a PropertyLinkSubList object,
+        # that automatically detect multiple instances of the same Part::Feature,
+        # and merges the sub-object lists (e.g. faces)
+        obj.NegFaces = real_faces
+    # return the newly created Python object
+    return obj
+
+class _VHPort:
+    '''The EM VoxHenry Port object'''
+    def __init__(self, obj):
+        # save the object in the class, to store or retrieve specific data from it
+        # from within the class
+        self.Object = obj
+        ''' Add properties '''
+        obj.addProperty("App::PropertyLinkSubList", "PosFaces", "EM", QT_TRANSLATE_NOOP("App::Property","The list of faces forming the positive contact of the port"))
+        obj.addProperty("App::PropertyLinkSubList", "NegFaces", "EM", QT_TRANSLATE_NOOP("App::Property","The list of faces forming the negative contact of the port"))
+        obj.addProperty("App::PropertyBool","ShowVoxels","EM",QT_TRANSLATE_NOOP("App::Property","Show the voxelization"))
+        obj.addProperty("App::PropertyInteger","DeltaDist","EM",QT_TRANSLATE_NOOP("App::Property","Distance as percentage of the delta voxel dimension to consider a port face as belonging to a voxel"))
+        obj.addProperty("App::PropertyBool","isVoxelized","EM",QT_TRANSLATE_NOOP("App::Property","Flags if the port has been voxelized (read only)"),1)
+        obj.addProperty("App::PropertyIntegerList","PosVoxelContacts","EM",QT_TRANSLATE_NOOP("App::Property","Positive Contacts (hidden)"),4)
+        obj.addProperty("App::PropertyIntegerList","NegVoxelContacts","EM",QT_TRANSLATE_NOOP("App::Property","Negative Contacts (hidden)"),4)
+        obj.ShowVoxels = False
+        obj.Proxy = self
+        obj.DeltaDist = int(50 + 50/EMVHPORT_EPSDELTA)
+        obj.isVoxelized = False
+        obj.PosVoxelContacts = []
+        obj.NegVoxelContacts = []
+        self.posContactShapePoints = []
+        self.negContactShapePoints = []
+        self.Type = "VHPort"
+
+    def onChanged(self, obj, prop):
+        ''' take action if an object property 'prop' changed
+    '''
+        #FreeCAD.Console.PrintWarning("\n_VHPort onChanged(" + str(prop)+")\n") #debug
+        # on restore, some self.Objects are not there anymore (JSON does not serialize complex objects
+        # members of the class, so __getstate__() and __setstate__() skip them);
+        # so we must "re-attach" (re-create) the 'self.Objects'
+        if not hasattr(self,"Object"):
+            self.Object = obj
+        if prop == "DeltaDist":
+            self.flagVoxelizationInvalid()
+
+    def execute(self, obj):
+        ''' this method is mandatory. It is called on Document.recompute() 
+    '''
+        #FreeCAD.Console.PrintWarning("_VHPort execute()\n") #debug
+        # if no faces were assigned to the port, exit
+        if len(obj.PosFaces) == 0 and len(obj.NegFaces) == 0:
+            return
+        shape = None
+        # Check if the user selected to see the voxelization, and if the voxelization exists
+        if obj.ShowVoxels == True:
+            # get the VHSolver object
+            solver = getVHSolver()
+            if solver is not None:
+                gbbox = solver.Proxy.getGlobalBBox()
+                delta = solver.Proxy.getDelta()
+                # getting the voxel space may cause the voxelization of this VHConductor to become invalid,
+                # if the global bounding box is found to have changed, or VHSolver 'Delta' changed over time, etc.
+                voxelSpace = solver.Proxy.getVoxelSpace()
+                if obj.isVoxelized == False:
+                    FreeCAD.Console.PrintWarning(translate("EM","Cannot fulfill 'ShowVoxels', VHPort objects has not been voxelized, or voxelization is invalid (e.g. change in voxel space dimensions or no voxelized conductor). Voxelize it first.\n"))
+                else:
+                    self.posContactShapePoints = []
+                    posContact = self.createVoxelShellFastCoin(self.posContactShapePoints, obj.PosVoxelContacts,gbbox,delta,voxelSpace)
+                    self.negContactShapePoints = []
+                    negContact = self.createVoxelShellFastCoin(self.negContactShapePoints, obj.NegVoxelContacts,gbbox,delta,voxelSpace)
+                    if posContact and negContact:
+                        shape = True
+                    else:
+                        FreeCAD.Console.PrintWarning(translate("EM","Cannot create VHPort shell, voxelized pos or neg contact shell creation failed"))
+        if shape is None:
+            # if we don't show the voxelized view of the object, let's show the faces
+            self.posContactShapePoints = []
+            self.negContactShapePoints = []
+            faces = self.getFaces(obj.PosFaces)
+            posContact = Part.makeCompound(faces)
+            faces = self.getFaces(obj.NegFaces)
+            negContact = Part.makeCompound(faces)
+            shape = Part.makeCompound([posContact,negContact])
+            # and finally assign the shape (but only if we were able to create any)
+            obj.Shape = shape
+            # force the color, if FreeCAD has a GUI and therefore the object has a ViewObject.
+            # must do it from here, as from within the ViewObject we cannot force the reconstruction of the coin3D
+            # scenegraph representation, that is using the ShapeColor
+            if FreeCAD.GuiUp:
+                obj.ViewObject.DiffuseColor = [obj.ViewObject.PosPortColor for x in range(0,len(obj.PosFaces))] + [obj.ViewObject.NegPortColor for x in range(0,len(obj.NegFaces))]
+        else:
+            # make a dummy empty shape. Representation is through custom coin3d scenegraph.
+            obj.Shape = Part.makeShell([])
+        #FreeCAD.Console.PrintWarning("_VHPort execute() ends\n") #debug
+
+    def getFaces(self,faceSubObjs):
+        ''' Get the face objects from an App::PropertyLinkSubList
+        
+            'faceSubObjs' an App::PropertyLinkSubList list of objects and face names. Each element of the list
+                has the format (Part::Feature, ('FaceXXX',)) where XXX is the face number.
+                The tuple ('FaceXXX',) may also contain multiple face names.
+                
+            Returns a list of face objects
+    '''
+        faces = []
+        for obj in faceSubObjs:
+            if obj[0].isDerivedFrom("Part::Feature"):
+                for sub in obj[1]:
+                        if "Face" in sub:
+                            fn = int(sub[4:])-1
+                            faces.append(obj[0].Shape.Faces[fn])
+        return faces
+
+
+    def createVoxelShell(self,contacts,gbbox,delta,voxelSpace=None):
+        ''' Creates a shell composed by the external faces of a voxelized port.
+        
+            'contacts' is the list of contacts (see voxelizeContact() for the format)
+            'gbbox' (FreeCAD.BoundBox) is the overall bounding box
+            'delta' is the voxels size length
+            'voxelSpace' (Numpy 3D array) is the voxel tensor of the overall space 
+            
+            Remark: the VHPort must have already been voxelized
+    '''
+        if voxelSpace is None:
+            return
+        # small displacement w.r.t. delta
+        epsdelta = delta/EMVHPORT_EPSDELTA
+        # vertexes of the six faces (with a slight offset)
+        vertexes = [[Vector(delta+epsdelta,0,0), Vector(delta+epsdelta,delta,0), Vector(delta+epsdelta,delta,delta), Vector(delta+epsdelta,0,delta)],
+                    [Vector(-epsdelta,0,0), Vector(-epsdelta,0,delta), Vector(-epsdelta,delta,delta), Vector(-epsdelta,delta,0)],
+                    [Vector(0,delta+epsdelta,0), Vector(0,delta+epsdelta,delta), Vector(delta,delta+epsdelta,delta), Vector(delta,delta+epsdelta,0)],
+                    [Vector(0,-epsdelta,0), Vector(delta,-epsdelta,0), Vector(delta,-epsdelta,delta), Vector(0,-epsdelta,delta)],
+                    [Vector(0,0,delta+epsdelta), Vector(delta,0,delta+epsdelta), Vector(delta,delta,delta+epsdelta), Vector(0,delta,delta+epsdelta)],
+                    [Vector(0,0,-epsdelta), Vector(0,delta,-epsdelta), Vector(delta,delta,-epsdelta), Vector(delta,0,-epsdelta)]]
+        surfList = []
+        # and now iterate through all the contact faces, and create FreeCAD Part.Faces
+        for contact in contacts:
+            vbase = Vector(gbbox.XMin + contact[0] * delta, gbbox.YMin + contact[1] * delta, gbbox.ZMin + contact[2] * delta)
+            # the third element of 'contact' is the
+            # index of the sides, order is ['+x', '-x', '+y', '-y', '+z', '-z']
+            vertex = vertexes[contact[3]]
+            # create the face
+            # calculate the vertexes
+            v11 = vbase + vertex[0]
+            v12 = vbase + vertex[1]
+            v13 = vbase + vertex[2]
+            v14 = vbase + vertex[3]
+            # now make the face
+            poly = Part.makePolygon( [v11,v12,v13,v14,v11])
+            contFace = Part.Face(poly)
+            surfList.append(contFace)
+        # create the shell out of the list of faces
+        contactShell = None
+        if len(surfList) > 0:
+            # create a shell. Does not need to be solid.
+            contactShell = Part.makeShell(surfList)
+        return contactShell
+
+    def createVoxelShellFastCoin(self,shapePoints,contacts,gbbox,delta,voxelSpace=None):
+        ''' Creates a shell composed by the external faces of a voxelized port.
+        
+            'contacts' is the list of contacts (see voxelizeContact() for the format)
+            'gbbox' (FreeCAD.BoundBox) is the overall bounding box
+            'delta' is the voxels size length
+            'voxelSpace' (Numpy 3D array) is the voxel tensor of the overall space 
+            
+            Remark: the VHPort must have already been voxelized
+    '''
+        if voxelSpace is None:
+            return None
+        # small displacement w.r.t. delta
+        epsdelta = delta/EMVHPORT_EPSDELTA
+        # vertexes of the six faces (with a slight offset)
+        vertexes = [[Vector(delta+epsdelta,0,0), Vector(delta+epsdelta,delta,0), Vector(delta+epsdelta,delta,delta), Vector(delta+epsdelta,0,delta)],
+                    [Vector(-epsdelta,0,0), Vector(-epsdelta,0,delta), Vector(-epsdelta,delta,delta), Vector(-epsdelta,delta,0)],
+                    [Vector(0,delta+epsdelta,0), Vector(0,delta+epsdelta,delta), Vector(delta,delta+epsdelta,delta), Vector(delta,delta+epsdelta,0)],
+                    [Vector(0,-epsdelta,0), Vector(delta,-epsdelta,0), Vector(delta,-epsdelta,delta), Vector(0,-epsdelta,delta)],
+                    [Vector(0,0,delta+epsdelta), Vector(delta,0,delta+epsdelta), Vector(delta,delta,delta+epsdelta), Vector(0,delta,delta+epsdelta)],
+                    [Vector(0,0,-epsdelta), Vector(0,delta,-epsdelta), Vector(delta,delta,-epsdelta), Vector(delta,0,-epsdelta)]]
+        # and now iterate through all the contact faces, and create FreeCAD Part.Faces
+        # The contact list is flat (to be able to store it as a PropertyIntegerList) so must go in steps of 4
+        for contactIndex in range(0,len(contacts),4):
+            vbase = Vector(gbbox.XMin + contacts[contactIndex] * delta, gbbox.YMin + contacts[contactIndex+1] * delta, gbbox.ZMin + contacts[contactIndex+2] * delta)
+            # the third element of 'contact' is the
+            # index of the sides, order is ['+x', '-x', '+y', '-y', '+z', '-z']
+            vertex = vertexes[contacts[contactIndex+3]]
+            # create the face
+            # calculate the vertexes
+            v11 = vbase + vertex[0]
+            v12 = vbase + vertex[1]
+            v13 = vbase + vertex[2]
+            v14 = vbase + vertex[3]
+            # now make the face
+            shapePoints.extend([v11,v12,v13,v14])
+        # create the shell out of the list of faces
+        if len(shapePoints) > 0:
+            return True
+        else:
+            return None
+
+    def voxelizePort(self):
+        ''' Voxelize the port object, i.e. find all the voxel faces belonging to the port
+            
+            The two list of voxel faces are assigned to internal variables
+    '''
+        if len(self.Object.PosFaces) == 0 and len(self.Object.NegFaces) == 0:
+            FreeCAD.Console.PrintWarning(translate("EM","Cannot voxelize port, no faces assigned to the port\n"))
+            return
+        # get the VHSolver object
+        solver = getVHSolver()
+        if solver is None:
+             return
+        FreeCAD.Console.PrintMessage(translate("EM","Starting voxelization of port ") + self.Object.Label + "...\n")
+        # get global parameters from the VHSolver object
+        gbbox = solver.Proxy.getGlobalBBox()
+        delta = solver.Proxy.getDelta()
+        voxelSpace = solver.Proxy.getVoxelSpace()
+        if voxelSpace is None:
+            FreeCAD.Console.PrintWarning(translate("EM","VoxelSpace not valid, cannot voxelize port\n"))
+            return
+        self.PosVoxelFaces = None
+        self.NegVoxelFaces = None
+        if len(self.Object.PosFaces) > 0:
+            self.Object.PosVoxelContacts = self.voxelizeContact(self.Object.PosFaces,gbbox,delta,self.Object.DeltaDist/100.0,voxelSpace)
+        if len(self.Object.NegFaces) > 0:
+            self.Object.NegVoxelContacts = self.voxelizeContact(self.Object.NegFaces,gbbox,delta,self.Object.DeltaDist/100.0,voxelSpace)
+        if len(self.Object.PosVoxelContacts) == 0 or len(self.Object.NegVoxelContacts) == 0:
+            FreeCAD.Console.PrintWarning(translate("EM","No voxelized contacts created, could not voxelize port. Is there any voxelized conductor in the space by the port?\n"))
+        else:
+            self.Object.isVoxelized = True
+            # if just voxelized, cannot show voxels; and if there was an old shell representing
+            # the previoius voxelization, must clear it
+            self.Object.ShowVoxels = False
+        FreeCAD.Console.PrintMessage(translate("EM","Voxelization of the port completed.\n"))
+
+    def voxelizeContact(self,faceSubobjs,gbbox,delta,deltadist,voxelSpace=None):
+        ''' Find the voxel surface sides corresponding to the given contact surface
+            (face) of an object. The object must have already been voxelized.
+            
+            'face' is the object face
+            'condIndex' (integer) is the index of the object to which the face belongs.
+                    It defines the object conductivity.
+            'gbbox' (FreeCAD.BoundBox) is the overall bounding box
+            'delta' is the voxels size length
+            'voxelSpace' (Numpy 3D array) is the voxel tensor of the overall space
+            'createShell' (bool) creates a shell out of the contact faces
+            
+            Returns a list of surfaces in the format x,y,z,voxside (all integers) repeated n times where
+            x, y, z are the voxel position indexes, while voxside is '+x', '-x',
+            '+y', '-y', '+z', '-z' according the the impacted surface of the voxel.
+            The list is flat to allow it to be stored in a PropertyIntegerList 
+    '''
+        if voxelSpace is None:
+            return []
+        contactList = []
+        # get the faces bbox
+        faces = self.getFaces(faceSubobjs)
+        if len(faces) == 0:
+            return []
+        bbox = FreeCAD.BoundBox()
+        for face in faces:
+            bbox.add(face.BoundBox)
+        if not bbox.isValid():
+            return []
+        # check if we are still within the global bbox
+        if not gbbox.isInside(bbox):
+            FreeCAD.Console.PrintWarning(translate("EM","Port faces bounding box is larger than the global bounding box. Cannot voxelize port.\n"))
+            return []
+        # now must find the voxel set that contains the faces bounding box
+        # with a certain slack - it could be the next voxel,
+        # if the surface is at the boundary between voxels.
+        # Find the voxel that contains the bbox min point
+        # (if negative, take zero)
+        min_x = max(int((bbox.XMin - gbbox.XMin)/delta)-2, 0)
+        min_y = max(int((bbox.YMin - gbbox.YMin)/delta)-2, 0)
+        min_z = max(int((bbox.ZMin - gbbox.ZMin)/delta)-2, 0)
+        # find the voxel that contains the bbox max point
+        # (if larger than the voxelSpace, set to voxelSpace max dim,
+        # we already verified that 'bbox' fits into 'gbbox')
+        vs_size = voxelSpace.shape
+        max_x = min(int((bbox.XMax - gbbox.XMin)/delta)+2, vs_size[0]-1)
+        max_y = min(int((bbox.YMax - gbbox.YMin)/delta)+2, vs_size[1]-1)
+        max_z = min(int((bbox.ZMax - gbbox.ZMin)/delta)+2, vs_size[2]-1)
+        # create a Part.Vertex that we can use to test the distance
+        # to the face (as it is a TopoShape)
+        vec = FreeCAD.Vector(0,0,0)
+        testVertex = Part.Vertex(vec)
+        # this is half the side of the voxel
+        halfdelta = delta/2.0
+        # array to find the six neighbors 
+        sides = [(1,0,0), (-1,0,0), (0,1,0), (0,-1,0), (0,0,1), (0,0,-1)]
+        # index of the sides, order is ['+x', '-x', '+y', '-y', '+z', '-z']
+        sideStrs = range(6)
+        # centers of the sides, with respect to the lower corner (with the smallest coordinates)
+        sideCenters = [Vector(delta,halfdelta,halfdelta), Vector(0.0,halfdelta,halfdelta),
+                        Vector(halfdelta,delta,halfdelta), Vector(halfdelta,0.0,halfdelta),
+                        Vector(halfdelta,halfdelta,delta), Vector(halfdelta,halfdelta,0.0)]
+        # and now iterate to find which voxel is inside the bounding box of the 'face',
+        vbase = Vector(gbbox.XMin + min_x * delta, gbbox.YMin + min_y * delta, gbbox.ZMin + min_z * delta)
+        for step_x in range(min_x,max_x+1):
+            vbase.y = gbbox.YMin + min_y * delta
+            for step_y in range(min_y,max_y+1):
+                vbase.z = gbbox.ZMin + min_z * delta
+                for step_z in range(min_z,max_z+1):
+                    # check if voxel is belonging to an object
+                    if voxelSpace[step_x,step_y,step_z] != 0:
+                        # scan the six neighbor voxels, to see if they are belonging to the conductor or not.
+                        # If they are not belonging to the conductor, or if the voxel space is finished, the current voxel
+                        # side in the direction of the empty voxel is an external surface
+                        for side, sideStr, sideCenter in zip(sides,sideStrs,sideCenters):
+                            is_surface = False
+                            nextVoxelIndexes = [step_x+side[0],step_y+side[1],step_z+side[2]]
+                            if (nextVoxelIndexes[0] > max_x or nextVoxelIndexes[0] < 0 or
+                               nextVoxelIndexes[1] > max_y or nextVoxelIndexes[1] < 0 or
+                               nextVoxelIndexes[2] > max_z or nextVoxelIndexes[2] < 0):
+                                is_surface = True
+                            else:
+                                if voxelSpace[nextVoxelIndexes[0],nextVoxelIndexes[1],nextVoxelIndexes[2]] == 0:
+                                    is_surface = True
+                            if is_surface == True:
+                                testVertex.Placement.Base = vbase + sideCenter
+                                # if the point is close enough to the face(s), we consider
+                                # the voxel surface as belonging to the voxelized face(s);
+                                # to this goal, take the shortest distance from any of the faces
+                                mindist = bbox.DiagonalLength
+                                for face in faces:
+                                    dist = abs(testVertex.distToShape(face)[0])
+                                    if dist < mindist:
+                                        mindist = dist
+                                if mindist < (delta*deltadist):
+                                    contactList.extend([step_x,step_y,step_z,sideStr])
+                    vbase.z += delta
+                vbase.y += delta
+            vbase.x += delta
+        return contactList
+         
+    def flagVoxelizationInvalid(self):
+        ''' Flags the voxelization as invalid
+    '''
+        self.Object.isVoxelized = False
+        self.Object.ShowVoxels = False
+
+    def getBaseObj(self):
+        ''' Retrieves the Base object.
+        
+            Returns the Base object.
+    '''
+        return self.Object.Base
+
+    def getCondIndex(self):
+        ''' Retrieves the conductor index.
+        
+            Returns the int16 conductor index.
+    '''
+        return self.Object.CondIndex
+
+    def setVoxelState(self,isVoxelized):
+        ''' Sets the voxelization state.
+    '''
+        self.Object.isVoxelized = isVoxelized
+
+    def serialize(self,fid):
+        ''' Serialize the object to the 'fid' file descriptor
+    '''
+        # index of the sides, order is ['+x', '-x', '+y', '-y', '+z', '-z']
+        sideStrs = range(6)
+        
+        if self.Object.isVoxelized == True:
+            fid.write("* Port " + str(self.Object.Label) + "\n")
+            name = "N " + str(self.Object.Label) + " P "
+            self.serializeContact(fid,name,self.Object.PosVoxelContacts)
+            name = "N " + str(self.Object.Label) + " N "
+            self.serializeContact(fid,name,self.Object.NegVoxelContacts)
+        else:
+            FreeCAD.Console.PrintWarning(translate("EM","Object not voxelized, cannot serialize ") + str(self.Object.Label) + "\n")
+
+    def serializeContact(self,fid,name,contacts):
+        ''' Serialize the contact to the 'fid' file descriptor
+        
+        'contacts' is the list of contacts (see voxelizeContact() for the format)
+        
+    '''
+        for contactIndex in range(0,len(contacts),4):
+            # remark: VoxHenry voxel tensor is 1-based, not 0-based. Must add 1
+            fid.write(name + " " + str(contacts[contactIndex+0]+1) + " " + str(contacts[contactIndex+1]+1) + " " + str(contacts[contactIndex+2]+1) + " " + EMVHPORT_SIDESTRS[contacts[contactIndex+3]] + "\n") 
+
+    def __getstate__(self):
+        # JSON does not understand FreeCAD.Vector, so need to convert to tuples
+        negConShapePointsJSON = [(x[0],x[1],x[2]) for x in self.negContactShapePoints]
+        posConShapePointsJSON = [(x[0],x[1],x[2]) for x in self.posContactShapePoints]
+        dictForJSON = {'nsp':negConShapePointsJSON,'psp':posConShapePointsJSON,'type':self.Type}
+        #FreeCAD.Console.PrintMessage("Save\n"+str(dictForJSON)+"\n") #debug
+        return dictForJSON
+
+    def __setstate__(self,dictForJSON):
+        if dictForJSON:
+            #FreeCAD.Console.PrintMessage("Load\n"+str(dictForJSON)+"\n") #debug
+            # no need to convert back to FreeCAD.Vectors, 'shapePoints' can also be tuples
+            self.negContactShapePoints = dictForJSON['nsp']
+            self.posContactShapePoints = dictForJSON['psp']
+            self.Type = dictForJSON['type']
+  
+class _ViewProviderVHPort:
+    def __init__(self, vobj):
+        ''' Set this object to the proxy object of the actual view provider '''
+        vobj.addProperty("App::PropertyColor","PosPortColor","Base","")
+        vobj.addProperty("App::PropertyColor","NegPortColor","Base","")
+        vobj.PosPortColor = EMVHPORT_DEF_POSPORTCOLOR
+        vobj.NegPortColor = EMVHPORT_DEF_NEGPORTCOLOR
+        # set also default LineColor
+        vobj.LineColor = EMVHPORT_DEF_LINECOLOR
+        # remark: these associations must *follow* the addition of the custom properties,
+        # or attach() will be called before the properties are created
+        vobj.Proxy = self
+        self.VObject = vobj
+        self.Object = vobj.Object
+        
+    def attach(self, vobj):
+        ''' Setup the scene sub-graph of the view provider, this method is mandatory '''
+        # on restore, self.Object is not there anymore (JSON does not serialize complex objects
+        # members of the class, so __getstate__() and __setstate__() skip them);
+        # so we must "re-attach" (re-create) the 'self.Object'
+        self.Object = vobj.Object
+        self.VObject = vobj
+        # actual representation
+        self.switch = coin.SoSwitch()
+        self.hints = coin.SoShapeHints()
+        self.style1 = coin.SoDrawStyle()
+        self.style2 = coin.SoDrawStyle()
+        self.materialPos = coin.SoMaterial()
+        self.materialNeg = coin.SoMaterial()
+        self.linecolor = coin.SoBaseColor()
+        self.dataPos = coin.SoCoordinate3()
+        self.dataNeg = coin.SoCoordinate3()
+        self.facePos = coin.SoFaceSet()
+        self.faceNeg = coin.SoFaceSet()
+        # init
+        # A shape hints tells the ordering of polygons.
+        # This ensures double-sided lighting.
+        self.hints.vertexOrdering = coin.SoShapeHints.COUNTERCLOCKWISE
+        self.hints.faceType = coin.SoShapeHints.CONVEX
+        # init styles
+        self.style1.style = coin.SoDrawStyle.FILLED
+        self.style2.style = coin.SoDrawStyle.LINES
+        self.style2.lineWidth = self.VObject.LineWidth
+        # init color
+        self.materialPos.diffuseColor.setValue(self.VObject.PosPortColor[0],self.VObject.PosPortColor[1],self.VObject.PosPortColor[2])
+        self.materialPos.transparency = self.VObject.Transparency/100.0
+        self.materialNeg.diffuseColor.setValue(self.VObject.NegPortColor[0],self.VObject.NegPortColor[1],self.VObject.NegPortColor[2])
+        self.materialNeg.transparency = self.VObject.Transparency/100.0
+        self.linecolor.rgb.setValue(self.VObject.LineColor[0],self.VObject.LineColor[1],self.VObject.LineColor[2])
+        # instructs to visit the first child (this is used to toggle visiblity)
+        self.switch.whichChild = coin.SO_SWITCH_ALL
+        #  scene
+        #sep = coin.SoSeparator()
+        # not using a separator, but a FreeCAD Selection node
+        sep = coin.SoType.fromName("SoFCSelection").createInstance()
+        sep.documentName.setValue(self.Object.Document.Name)
+        sep.objectName.setValue(self.Object.Name)
+        sep.subElementName.setValue("Face")
+        # now adding the common children
+        sep.addChild(self.hints)
+        sep.addChild(self.switch)
+        # and finally the two groups, the first is the contour lines,
+        # the second is the filled faces, so we can switch between
+        # "Flat Lines", "Shaded" and "Wireframe". Note: not implementing "Points"
+        group0Line = coin.SoGroup()
+        self.switch.addChild(group0Line)
+        group0Line.addChild(self.style2)
+        group0Line.addChild(self.linecolor)
+        group0Line.addChild(self.dataPos)
+        group0Line.addChild(self.facePos)
+        group0Line.addChild(self.dataNeg)
+        group0Line.addChild(self.faceNeg)
+        group1Face = coin.SoGroup()
+        self.switch.addChild(group1Face)
+        group1Face.addChild(self.materialPos)
+        group1Face.addChild(self.style1)
+        group1Face.addChild(self.dataPos)        
+        group1Face.addChild(self.facePos)
+        group1Face.addChild(self.materialNeg)
+        group1Face.addChild(self.style1)
+        group1Face.addChild(self.dataNeg)        
+        group1Face.addChild(self.faceNeg)
+        self.VObject.RootNode.addChild(sep)
+        #FreeCAD.Console.PrintMessage("ViewProvider attach() completed\n")
+        return
+        
+    def updateData(self, fp, prop):
+        ''' If a property of the data object has changed we have the chance to handle this here 
+            'fp' is the handled feature (the object)
+            'prop' is the name of the property that has changed
+    '''
+        #FreeCAD.Console.PrintMessage("ViewProvider updateData(),  property: " + str(prop) + "\n") # debug
+        if prop == "Shape":
+            numpointsPos = len(self.Object.Proxy.posContactShapePoints)
+            numpointsNeg = len(self.Object.Proxy.negContactShapePoints)
+            # this can be used to reset the number of points to the value actually needed
+            # (e.g. shorten the array, or pre-allocate it). However setValue() will automatically
+            # increase the array size if needed, and will NOT shorten it if less values are inserted
+            # This is less memory efficient, but faster; and in using the points in the SoFaceSet,
+            # we specify how many points (vertices) we want out of the total array, so no issue
+            # if the array is longer
+            #self.data.point.setNum(numpoints)
+            self.dataPos.point.setValues(0,numpointsPos,self.Object.Proxy.posContactShapePoints)
+            self.dataNeg.point.setValues(0,numpointsNeg,self.Object.Proxy.negContactShapePoints)
+            # 'numvertices' contains the number of vertices used for each face.
+            # Here all faces are quadrilaterals, so this is a long array of number '4's
+            numverticesPos = [4 for i in range(int(numpointsPos/4))]
+            numverticesNeg = [4 for i in range(int(numpointsNeg/4))]
+            # set the number of vertices per each face, for a total of len(numvertices) faces, starting from 0
+            # but must first delete all the old values, otherwise the remaining panels with vertices from
+            # 'numvertices+1' will still be shown
+            self.facePos.numVertices.deleteValues(0,-1)
+            self.facePos.numVertices.setValues(0,len(numverticesPos),numverticesPos)
+            self.faceNeg.numVertices.deleteValues(0,-1)
+            self.faceNeg.numVertices.setValues(0,len(numverticesNeg),numverticesNeg)
+            #FreeCAD.Console.PrintMessage("numpoints " + str(numpoints) + "; numvertices " + str(numvertices) + "\n") # debug
+            #FreeCAD.Console.PrintMessage("self.Object.Proxy.shapePoints " + str(self.Object.Proxy.shapePoints) + "\n") # debug
+            #FreeCAD.Console.PrintMessage("self.data.point " + str(self.data.point.get()) + "\n") # debug
+            #FreeCAD.Console.PrintMessage("updateData() shape!\n") # debug
+        return
+
+    def onChanged(self, vp, prop):
+        ''' If the 'prop' property changed for the ViewProvider 'vp' '''
+        #FreeCAD.Console.PrintMessage("ViewProvider onChanged(), property: " + str(prop) + "\n") # debug
+        if not hasattr(self,"VObject"):
+            self.VObject = vp
+         # if there is a coin3d custom representation
+        if self.Object.isVoxelized and self.Object.ShowVoxels:
+            if prop == "PosPortColor" or prop == "NegPortColor":
+                self.materialPos.diffuseColor.setValue(self.VObject.PosPortColor[0],self.VObject.PosPortColor[1],self.VObject.PosPortColor[2])
+                self.materialNeg.diffuseColor.setValue(self.VObject.NegPortColor[0],self.VObject.NegPortColor[1],self.VObject.NegPortColor[2])
+            if prop == "Visibility" or prop=="DisplayMode":
+                if not vp.Visibility:
+                    self.switch.whichChild = coin.SO_SWITCH_NONE
+                else:
+                    if self.VObject.DisplayMode == "Wireframe":
+                        self.switch.whichChild = 0
+                    elif self.VObject.DisplayMode == "Shaded":
+                        self.switch.whichChild = 1
+                    else:
+                        self.switch.whichChild = coin.SO_SWITCH_ALL
+            if prop == "LineColor":
+                self.linecolor.rgb.setValue(self.VObject.LineColor[0],self.VObject.LineColor[1],self.VObject.LineColor[2])
+            if prop == "LineWidth":
+                self.style2.lineWidth = self.VObject.LineWidth
+            if prop == "Transparency":
+                self.materialPos.transparency = self.VObject.Transparency/100.0
+                self.materialNeg.transparency = self.VObject.Transparency/100.0
+        # otherwise the VHPort is based on a Shape containing the faces composing the port
+        else:
+            if prop == "PosPortColor" or prop == "NegPortColor":
+                if vp.Object.Shape is not None:
+                    # only if this is not a direct coin3d representation but a compound
+                    # of faces, color them according to which port they are
+                    if type(vp.Object.Shape) == Part.Compound:
+                        if len(vp.Object.Shape.Faces) >= 2:
+                            self.VObject.DiffuseColor = [self.VObject.PosPortColor for x in range(0,len(vp.Object.PosFaces))] + [self.VObject.NegPortColor for x in range(0,len(vp.Object.NegFaces))]
+
+    def getDefaultDisplayMode(self):
+        ''' Return the name of the default display mode. It must be defined in getDisplayModes. '''
+        return "Flat Lines"
+        
+    def getIcon(self):
+        ''' Return the icon which will appear in the tree view. This method is optional
+        and if not defined a default icon is shown.
+        '''
+        return os.path.join(iconPath, 'EM_VHPort.svg')
+
+    def __getstate__(self):
+        return None
+
+    def __setstate__(self,state):
+        return None
+
+class _CommandVHPort:
+    ''' The EM VoxHenry Conductor (VHPort) command definition
+'''
+    def GetResources(self):
+        return {'Pixmap'  : os.path.join(iconPath, 'EM_VHPort.svg') ,
+                'MenuText': QT_TRANSLATE_NOOP("EM_VHPort","VHPort"),
+                'Accel': "E, O",
+                'ToolTip': QT_TRANSLATE_NOOP("EM_VHPort","Creates a VoxHenry Port object from a set of faces")}
+                
+    def IsActive(self):
+        return not FreeCAD.ActiveDocument is None
+
+    def Activated(self):
+        # preferences
+        #p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/EM")
+        #self.Width = p.GetFloat("Width",200)
+        # get the selected object(s)
+        selection = FreeCADGui.Selection.getSelectionEx()
+        if len(selection) > 0:
+            FreeCAD.ActiveDocument.openTransaction(translate("EM","Create VHPort"))
+            FreeCADGui.addModule("EM")
+            FreeCADGui.doCommand('obj=EM.makeVHPortFromSel(FreeCADGui.Selection.getSelectionEx())')
+            # autogrouping, for later on
+            #FreeCADGui.addModule("Draft")
+            #FreeCADGui.doCommand("Draft.autogroup(obj)")
+            FreeCAD.ActiveDocument.commitTransaction()
+            FreeCAD.ActiveDocument.recompute()
+        else:
+            FreeCAD.Console.PrintWarning(translate("EM","No face selected for the creation of a VHPort (need at least two). Nothing done."))
+
+if FreeCAD.GuiUp:
+    FreeCADGui.addCommand('EM_VHPort',_CommandVHPort())

EM_VHSolver.py

@@ -0,0 +1,524 @@
+#***************************************************************************
+#*                                                                         *
+#*   Copyright (c) 2019                                                    *
+#*   FastFieldSolvers S.R.L., http://www.fastfieldsolvers.com              *
+#*                                                                         *
+#*   This program is free software; you can redistribute it and/or modify  *
+#*   it under the terms of the GNU Lesser General Public License (LGPL)    *
+#*   as published by the Free Software Foundation; either version 2 of     *
+#*   the License, or (at your option) any later version.                   *
+#*   for detail see the LICENCE text file.                                 *
+#*                                                                         *
+#*   This program is distributed in the hope that it will be useful,       *
+#*   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+#*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+#*   GNU Library General Public License for more details.                  *
+#*                                                                         *
+#*   You should have received a copy of the GNU Library General Public     *
+#*   License along with this program; if not, write to the Free Software   *
+#*   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+#*   USA                                                                   *
+#*                                                                         *
+#***************************************************************************
+
+
+__title__="FreeCAD E.M. Workbench VoxHenry Solver Class"
+__author__ = "FastFieldSolvers S.R.L."
+__url__ = "http://www.fastfieldsolvers.com"
+
+# defines
+#
+# default solver bbox color
+EMVHSOLVER_DEF_SHAPECOLOR = (0.33,1.0,1.0)
+# default solver bbox transparency
+EMVHSOLVER_DEF_TRANSPARENCY = 90
+# default voxel size
+EMVHSOLVER_DEF_DELTA = 1.0
+# minimum frequency that can be specified
+EMVHSOLVER_DEF_MINFREQ = 1e-6
+# maximum index value that can be contained in the voxel space array (made of int16)
+EMVHSOLVER_COND_ID_OVERFLOW = 65535
+# allowed .units
+EMVHSOLVER_UNITS = ["km", "m", "cm", "mm", "um", "nm", "in", "mils"]
+EMVHSOLVER_UNITS_VALS = [1e3, 1, 1e-2, 1e-3, 1e-6, 1e-9, 2.54e-2, 1e-3]
+EMVHSOLVER_DEFUNITS = "um"
+EMVHSOLVER_DEFNHINC = 1
+EMVHSOLVER_DEFNWINC = 1
+EMVHSOLVER_DEFRW = 2
+EMVHSOLVER_DEFRH = 2
+EMVHSOLVER_DEFFMIN = 2.5e+09
+EMVHSOLVER_DEFFMAX = 1.0e+10
+EMVHSOLVER_DEFNDEC = 1
+# default input file name
+EMVHSOLVER_DEF_FILENAME = "voxhenry_input_file.vhr"
+
+import FreeCAD, FreeCADGui, Mesh, Part, MeshPart, Draft, DraftGeomUtils, os
+from FreeCAD import Vector
+import math
+import numpy as np
+
+if FreeCAD.GuiUp:
+    import FreeCADGui
+    from PySide import QtCore, QtGui
+    from DraftTools import translate
+    from PySide.QtCore import QT_TRANSLATE_NOOP
+else:
+    # \cond
+    def translate(ctxt,txt, utf8_decode=False):
+        return txt
+    def QT_TRANSLATE_NOOP(ctxt,txt):
+        return txt
+    # \endcond
+
+__dir__ = os.path.dirname(__file__)
+iconPath = os.path.join( __dir__, 'Resources' )
+
+def makeVHSolver(units=None,fmin=None,fmax=None,ndec=None,folder=None,filename=None,name='VHSolver'):
+    ''' Creates a VoxHenry Solver object (all statements needed for the simulation, and container for objects)
+    
+        'units' is the VoxHenry unit of measurement. Each unit in FreeCad will be
+            one unit of the default unit of measurement in VoxHenry.
+            Allowed values are: "km", "m", "cm", "mm", "um", "in", "mils".
+            Defaults to EMVHSOLVER_DEFUNITS
+        'fmin' is the float minimum simulation frequency 
+        'fmax' is the float maximum simulation frequency 
+        'ndec' is the float value defining how many frequency points per decade
+            will be simulated
+        'folder' is the folder into which the FastHenry file will be saved.
+            Defaults to the user's home path (e.g. in Windows "C:\\Documents
+             and Settings\\username\\My Documents", in Linux "/home/username")
+        'filename' is the name of the file that will be exported.
+            Defaults to EMVHSOLVER_DEF_FILENAME
+        'name' is the name of the object
+    Example:
+        solver = makeVHSolver()
+'''
+    obj = FreeCAD.ActiveDocument.addObject("Part::FeaturePython", name)
+    obj.Label = translate("EM", name)
+    # this adds the relevant properties to the object 
+    #'obj' (e.g. 'Base' property) making it a _VHSolver 
+    _VHSolver(obj)
+    # manage ViewProvider object
+    if FreeCAD.GuiUp:
+        _ViewProviderVHSolver(obj.ViewObject)
+        # set base ViewObject properties to user-selected values (if any)
+    if units in EMVHSOLVER_UNITS:
+        obj.units = units
+    else:
+        obj.units = EMVHSOLVER_DEFUNITS
+    if fmin is not None:
+        obj.fmin = fmin
+    else:
+        obj.fmin = EMVHSOLVER_DEFFMIN
+    if fmax is not None:
+        obj.fmax = fmax
+    else:
+        obj.fmax = EMVHSOLVER_DEFFMAX
+    if ndec is not None:
+        obj.ndec = ndec
+    else:
+        obj.ndec = EMVHSOLVER_DEFNDEC
+    if filename is not None:
+        obj.Filename = filename
+    else:
+        obj.Filename = EMVHSOLVER_DEF_FILENAME
+    if folder is not None:
+        obj.Folder = folder
+    else:
+        # if not specified, default to the user's home path
+        # (e.g. in Windows "C:\Documents and Settings\username\My Documents", in Linux "/home/username")
+        obj.Folder = FreeCAD.ConfigGet("UserHomePath")
+    # hide by default (would show the bbox when valid)
+    obj.ViewObject.hide()
+    # return the newly created Python object
+    return obj
+
+class _VHSolver:
+    '''The EM VoxHenry Solver object'''
+    def __init__(self, obj):
+        ''' Add properties '''
+        obj.addProperty("App::PropertyFloat","delta","EM",QT_TRANSLATE_NOOP("App::Property","Voxel size dimension ('delta' parameter in VoxHenry)"))
+        obj.addProperty("App::PropertyInteger","VoxelSpaceX","EM",QT_TRANSLATE_NOOP("App::Property","Voxel space dimension along X (read-only)"),1)
+        obj.addProperty("App::PropertyInteger","VoxelSpaceY","EM",QT_TRANSLATE_NOOP("App::Property","Voxel space dimension along Y (read-only)"),1)
+        obj.addProperty("App::PropertyInteger","VoxelSpaceZ","EM",QT_TRANSLATE_NOOP("App::Property","Voxel space dimension along Z (read-only)"),1)
+        obj.addProperty("App::PropertyInteger","VoxelSpaceDim","EM",QT_TRANSLATE_NOOP("App::Property","Voxel space dimension, total number of voxels (read-only)"),1)
+        obj.addProperty("App::PropertyEnumeration","units","EM",QT_TRANSLATE_NOOP("App::Property","The measurement units for all the dimensions"))
+        obj.addProperty("App::PropertyFloatConstraint","fmin","EM",QT_TRANSLATE_NOOP("App::Property","Lowest simulation frequency"))
+        obj.addProperty("App::PropertyFloatConstraint","fmax","EM",QT_TRANSLATE_NOOP("App::Property","Highest simulation frequency"))
+        obj.addProperty("App::PropertyFloat","ndec","EM",QT_TRANSLATE_NOOP("App::Property","Number of desired frequency points per decade"))
+        obj.addProperty("App::PropertyFloatList","freq","EM",QT_TRANSLATE_NOOP("App::Property","Frequencies for simulation"))
+        obj.addProperty("App::PropertyPath","Folder","EM",QT_TRANSLATE_NOOP("App::Property","Folder path for exporting the file in VoxHenry input file format"))
+        obj.addProperty("App::PropertyString","Filename","EM",QT_TRANSLATE_NOOP("App::Property","Simulation filename when exporting to VoxHenry input file format"))
+        obj.addProperty("App::PropertyBool","voxelSpaceValid","EM",QT_TRANSLATE_NOOP("App::Property","Flags the validity of the voxel space (read only)"),1)
+        obj.addProperty("App::PropertyInteger","condIndexGenerator","EM",QT_TRANSLATE_NOOP("App::Property","Latest index for conductor numbering (hidden)"),4)
+        obj.Proxy = self
+        obj.delta = EMVHSOLVER_DEF_DELTA
+        obj.units = EMVHSOLVER_UNITS
+        obj.voxelSpaceValid = False
+        obj.condIndexGenerator = 0
+        obj.freq = []
+        obj.fmin = (EMVHSOLVER_DEFFMIN, EMVHSOLVER_DEF_MINFREQ, 1e+20, EMVHSOLVER_DEF_MINFREQ)
+        obj.fmax = (EMVHSOLVER_DEFFMAX, EMVHSOLVER_DEF_MINFREQ, 1e+20, EMVHSOLVER_DEF_MINFREQ)
+        obj.fmin = EMVHSOLVER_DEFFMIN
+        self.bbox = FreeCAD.BoundBox()
+        self.voxelSpace = np.full((0,0,0), 0, np.int16)
+        self.oldDelta = obj.delta
+        self.Type = "VHSolver"
+        # save the object in the class, to store or retrieve specific data from it
+        # from within the class
+        self.Object = obj
+        self.justLoaded = False
+
+    def execute(self, obj):
+        ''' this method is mandatory. It is called on Document.recompute() 
+    '''
+        if self.bbox.isValid():
+            obj.Shape = Part.makeBox(self.bbox.XLength,self.bbox.YLength,self.bbox.ZLength,Vector(self.bbox.XMin,self.bbox.YMin,self.bbox.ZMin))
+            
+    def onChanged(self, obj, prop):
+        ''' take action if an object property 'prop' changed
+    '''
+        #FreeCAD.Console.PrintWarning("\n_VHSolver onChanged(" + str(prop)+")\n") #debug
+        if not hasattr(self,"Object"):
+            # on restore, self.Object is not there anymore (JSON does not serialize complex objects
+            # members of the class, so __getstate__() and __setstate__() skip them);
+            # so we must "re-attach" (re-create) the 'self.Object'
+            self.Object = obj
+        if prop == "delta":
+            # at creation 'oldDelta' does not yet exist (created after 'delta')
+            if hasattr(self,"oldDelta"):
+                if obj.delta != self.oldDelta:
+                    self.oldDelta = obj.delta
+                    # if changing 'Delta', must flag the voxel space as invalid
+                    obj.voxelSpaceValid = False
+                    self.flagVoxelizationInvalidAll()
+        if prop == "VoxelSpaceX" or prop == "VoxelSpaceY" or prop == "VoxelSpaceZ" or prop == "VoxelSpaceDim":
+            # if just changed read-only properties, clear the recompute flag (not needed)
+            obj.purgeTouched()
+        if prop == "fmin" or prop == "fmax" or prop == "ndec":
+            if hasattr(obj,"fmin") and hasattr(obj,"fmax") and hasattr(obj,"ndec"):
+                if self.Object.fmin > EMVHSOLVER_DEF_MINFREQ and self.Object.ndec > 0.0:
+                    # calculate all the frequency points
+                    # first calculate how many decades
+                    decades = math.log10(self.Object.fmax / self.Object.fmin)
+                    # then the total number of points, knowing the decades and the number of points per decade
+                    npoints = int(decades * self.Object.ndec)+1
+                    # step per decade
+                    logofstep = 1.0/self.Object.ndec
+                    # finally the frequencies
+                    self.Object.freq = [self.Object.fmin*math.pow(10,m*logofstep) for m in range(0,npoints)]
+                else:
+                    self.Object.freq = [1]
+                
+    def computeContainingBBox(self):
+        ''' Get the bounding box containing all the VHConductors in the document
+                   
+            Returns the global bounding box.
+            If there are no VHConductors, or if the VHConductors Base objects have no Shape,
+            the returned BoundBox is invalid (.isValid() on the returned BoundBox gives False)
+    '''
+        # create an empty bbox
+        gbbox = FreeCAD.BoundBox()
+        # get the document containing this object
+        doc = self.Object.Document
+        if doc is None:
+            FreeCAD.Console.PrintWarning(translate("EM","No active document available. Cannot compute containing BBox."))
+        else:
+            # get all the VHConductors
+            conds = [obj for obj in doc.Objects if Draft.getType(obj) == "VHConductor"]
+            for obj in conds:
+                gbbox.add(obj.Proxy.getBBox())
+        # if the the old bbox or the newly computed bbox is invalid, flag the voxel space as invalid
+        if (not gbbox.isValid()) or (not self.bbox.isValid()):
+            self.Object.voxelSpaceValid = False
+        else:
+            # if we just re-loaded the model, do not flag the bbox as invalid.
+            # the problem is that the Shape.BoundBox of the base objects of the VHConductors
+            # can be different if the object actually has a visible shape or not.
+            # At load time, if the object is invisible, its boundbox may be different. 
+            # However, if we knew it was valid at save time, no reason to invalidate it
+            if not self.justLoaded:
+                if (not gbbox.isInside(self.bbox)) and (not self.bbox.isInside(gbbox)):
+                    self.Object.voxelSpaceValid = False
+            else:
+                self.justLoaded = False
+        self.bbox = gbbox
+        return gbbox
+
+    def createVoxelSpace(self, bbox=None, delta=None):
+        ''' Creates the voxel tensor (3D array) in the given bounding box
+        
+            'bbox' is the overall FreeCAD.BoundBox bounding box
+            'delta' is the voxels size length
+            
+            Returns a voxel tensor as a Numpy 3D array.
+            If gbbox is None, returns None
+    '''
+        if bbox is None:
+            return None
+        if not bbox.isValid():
+            return None
+        if delta is None:
+            return None
+        if delta <= 0.0:
+            return None
+        # add 1.0 to always cover the bbox space with the voxels
+        stepsX = int(bbox.XLength/delta + 1.0)
+        stepsY = int(bbox.YLength/delta + 1.0)
+        stepsZ = int(bbox.ZLength/delta + 1.0)
+        # store info in the properties visible to the user (but read-only)
+        self.Object.VoxelSpaceX = stepsX
+        self.Object.VoxelSpaceY = stepsY
+        self.Object.VoxelSpaceZ = stepsZ
+        self.Object.VoxelSpaceDim = stepsX*stepsY*stepsZ
+        # create the 3D array of nodes as 16-bit integers (max 65k different conductivities)
+        voxelSpace=np.full((stepsX+1,stepsY+1,stepsZ+1), 0, np.int16)
+        return voxelSpace
+
+    def getVoxelSpace(self,force=False):
+        ''' Retrieves the voxel space. If not computed yet, or invalid, forces computation.
+            
+            'force' causes full recalculation of both the bbox and the voxel space
+            
+            Returns the voxel space tensor as a Numpy 3D array. If impossible to calculate, returns 'None'
+    '''
+        # get the document containing this object
+        doc = self.Object.Document
+        if doc is None:
+            FreeCAD.Console.PrintWarning(translate("EM","No active document available. Cannot compute the voxel space."))
+            return None
+        # first re-compute the global bbox. This may flag the voxel space as invalid.
+        self.computeContainingBBox()
+        # if the bounding box is invalid, no voxel space, no matter what
+        if not self.bbox.isValid():
+            self.voxelSpace = np.full((0,0,0), 0, np.int16)
+        # else if voxel space invalid, or forcing recalculation, let's compute it
+        elif (self.voxelSpace.size == 0) or (not self.Object.voxelSpaceValid) or force:
+            # create voxel space
+            self.voxelSpace = self.createVoxelSpace(self.bbox, self.Object.delta)
+            self.Object.voxelSpaceValid = True
+            # now flag all VHConductor and VHPort voxelizations as invalid
+            # get all the VHConductors
+            conds = [obj for obj in doc.Objects if Draft.getType(obj) == "VHConductor"]
+            for obj in conds:
+                obj.Proxy.flagVoxelizationInvalid()
+            # get all the VHPorts
+            ports = [obj for obj in doc.Objects if Draft.getType(obj) == "VHPort"]
+            for obj in ports:
+                obj.Proxy.flagVoxelizationInvalid()
+        # return the voxel space (may also be None)
+        return self.voxelSpace
+
+    def getGlobalBBox(self):
+        ''' Retrieves the bounding box. If not calculated yet, forces calculation
+        
+            Returns the global bbox as FreeCAD.BoundBox class
+    '''
+        return self.computeContainingBBox()
+        
+    def getDelta(self):
+        ''' Retrieves the voxel size.
+        
+            Returns the voxel size float value 'delta'.
+    '''
+        return self.Object.delta
+
+    def isSupercond(self):
+        ''' Check if there is any VHConductor specifying a lambda value (in this case,
+            must treat the system as containing superconductors)
+                   
+            Returns boolean 'True' if there are superconductors
+    '''
+        isSupercond = False
+        # get the document containing this object
+        doc = self.Object.Document
+        if doc is None:
+            FreeCAD.Console.PrintWarning(translate("EM","No active document available. Cannot check if there are superconductors."))
+        else:
+            # get all the VHConductors
+            conds = [obj for obj in doc.Objects if Draft.getType(obj) == "VHConductor"]
+            for obj in conds:
+                if obj.Lambda.Value > 0.0:
+                    isSupercond = True
+                    break
+        return isSupercond
+
+    def flagVoxelSpaceInvalid(self):
+        ''' Flags the voxel space as invalid
+    '''
+        self.Object.voxelSpaceValid = False
+
+    def getNextCondIndex(self):
+        ''' Generates a unique conductor index for marking the different VHConductors in the voxel space.
+        
+            Returns a unique integer.
+    '''
+        self.Object.condIndexGenerator = self.Object.condIndexGenerator + 1
+        if self.Object.condIndexGenerator > EMVHSOLVER_COND_ID_OVERFLOW:
+            FreeCAD.Console.PrintWarning(translate("EM","Conductor index generator overflowed int16 capacity! Cannot reliably mark VHConductors any more in the voxel space"))
+        return self.Object.condIndexGenerator
+
+    def voxelizeAll(self):
+        ''' Voxelize all VHConductors and VHPorts in the voxelSpace of the VHSolver object
+    '''
+        # get the document containing this object
+        doc = self.Object.Document
+        if doc is None:
+            FreeCAD.Console.PrintWarning(translate("EM","No active document available. Cannot voxelize conductors."))
+            return None
+        # get all VHConductors and VHPorts
+        conds = [obj for obj in doc.Objects if Draft.getType(obj) == "VHConductor"]
+        for cond in conds:
+            cond.Proxy.voxelizeConductor()
+        ports = [obj for obj in doc.Objects if Draft.getType(obj) == "VHPort"]
+        for port in ports:
+            port.Proxy.voxelizePort()
+
+    def flagVoxelizationInvalidAll(self):
+        ''' Invalidate the voxelization of all VHConductors and VHPorts
+    '''
+        # get the document containing this object
+        doc = self.Object.Document
+        if doc is None:
+            FreeCAD.Console.PrintWarning(translate("EM","No active document available. Cannot invalidate conductors."))
+            return None
+        # get all VHConductors and VHPorts
+        conds = [obj for obj in doc.Objects if Draft.getType(obj) == "VHConductor"]
+        for cond in conds:
+            cond.Proxy.flagVoxelizationInvalid()
+        ports = [obj for obj in doc.Objects if Draft.getType(obj) == "VHPort"]
+        for port in ports:
+            port.Proxy.flagVoxelizationInvalid()
+
+    def serialize(self,fid):
+        ''' Serialize the object to the 'fid' file descriptor
+    '''
+        fid.write("* VoxHenry input file created using FreeCAD's ElectroMagnetic Workbench\n")
+        fid.write("* See http://www.freecad.org and http://www.fastfieldsolvers.com\n")
+        fid.write("\n")
+        fid.write("* Frequency points (Hz)\n")
+        fid.write("freq=")
+        for freq in self.Object.freq:
+            fid.write(" "+str(freq))
+        fid.write("\n")
+        fid.write("\n")
+        fid.write("* Voxel size (m)\n")
+        scaledDelta = self.Object.delta * EMVHSOLVER_UNITS_VALS[EMVHSOLVER_UNITS.index(self.Object.units)]
+        fid.write("dx=" + str(scaledDelta) + "\n")
+        fid.write("\n")
+        fid.write("* Voxel grid dimension in voxel units: x, y, z\n")
+        fid.write("LMN=" + str(self.Object.VoxelSpaceX) + "," + str(self.Object.VoxelSpaceY) + "," + str(self.Object.VoxelSpaceZ) + "\n")
+        fid.write("\n")
+
+    def __getstate__(self):
+        voxelspacedim = (self.Object.VoxelSpaceX+1,self.Object.VoxelSpaceY+1,self.Object.VoxelSpaceZ+1)
+        bboxcoord = (self.bbox.XMin,self.bbox.YMin,self.bbox.ZMin,self.bbox.XMax,self.bbox.YMax,self.bbox.ZMax)
+        voxelSpaceConds =  self.voxelSpace.nonzero()
+        voxelSpaceVals = self.voxelSpace[voxelSpaceConds].tolist()
+        voxelSpaceCoordX = voxelSpaceConds[0].tolist()
+        voxelSpaceCoordY = voxelSpaceConds[1].tolist()
+        voxelSpaceCoordZ = voxelSpaceConds[2].tolist()
+        dictForJSON = {'oldD':self.oldDelta,'vsDim':voxelspacedim,'vsX':voxelSpaceCoordX,'vsY':voxelSpaceCoordY,'vsZ':voxelSpaceCoordZ,'vsVals':voxelSpaceVals,'bbox':bboxcoord,'type':self.Type}
+        #FreeCAD.Console.PrintMessage("Save\n"+str(dictForJSON)+"\n") #debug
+        return dictForJSON
+
+    def __setstate__(self,dictForJSON):
+        if dictForJSON:
+            #FreeCAD.Console.PrintMessage("Load\n"+str(dictForJSON)+"\n") #debug
+            self.oldDelta = dictForJSON['oldD']
+            bboxcoord = dictForJSON['bbox']
+            self.bbox = FreeCAD.BoundBox(bboxcoord[0],bboxcoord[1],bboxcoord[2],bboxcoord[3],bboxcoord[4],bboxcoord[5])
+            voxelspacedim = dictForJSON['vsDim']        
+            self.voxelSpace = np.full(voxelspacedim,0,np.int16)
+            voxelSpaceConds = (np.array(dictForJSON['vsX']),np.array(dictForJSON['vsY']),np.array(dictForJSON['vsZ']))
+            self.voxelSpace[voxelSpaceConds] = dictForJSON['vsVals']
+            self.Type = dictForJSON['type']
+        self.justLoaded = True
+            
+class _ViewProviderVHSolver:
+    def __init__(self, vobj):
+        ''' Set this object to the proxy object of the actual view provider '''
+        vobj.ShapeColor = EMVHSOLVER_DEF_SHAPECOLOR
+        vobj.Transparency = EMVHSOLVER_DEF_TRANSPARENCY
+        vobj.Proxy = self
+
+    def attach(self, obj):
+        ''' Setup the scene sub-graph of the view provider, this method is mandatory '''
+        return
+
+    def updateData(self, fp, prop):
+        ''' If a property of the handled feature has changed we have the chance to handle this here '''
+        #FreeCAD.Console.PrintMessage("ViewProvider updateData(),  property: " + str(prop) + "\n") # debug
+        return
+
+    def getDefaultDisplayMode(self):
+        ''' Return the name of the default display mode. It must be defined in getDisplayModes. '''
+        return "Flat Lines"
+
+    def onChanged(self, vp, prop):
+        ''' If the 'prop' property changed for the ViewProvider 'vp' '''
+        #FreeCAD.Console.PrintMessage("ViewProvider onChanged(), property: " + str(prop) + "\n") # debug
+
+    def getIcon(self):
+        ''' Return the icon which will appear in the tree view. This method is optional
+        and if not defined a default icon is shown.
+        '''
+        return os.path.join(iconPath, 'EM_VHSolver.svg')
+
+    def __getstate__(self):
+        return None
+
+    def __setstate__(self,state):
+        return None
+            
+class _CommandVHSolver:
+    ''' The EM VoxHenry Solver command definition
+'''
+    def GetResources(self):
+        return {'Pixmap'  : os.path.join(iconPath, 'EM_VHSolver.svg') ,
+                'MenuText': QT_TRANSLATE_NOOP("EM_VHSolver","VHSolver"),
+                'Accel': "E, Y",
+                'ToolTip': QT_TRANSLATE_NOOP("EM_VHSolver","Creates a VoxHenry Solver object")}
+                
+    def IsActive(self):
+        return not FreeCAD.ActiveDocument is None
+
+    def Activated(self):
+        # preferences
+        #p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/EM")
+        #self.Width = p.GetFloat("Width",200)
+        FreeCAD.ActiveDocument.openTransaction(translate("EM","Create VHSolver"))
+        FreeCADGui.addModule("EM")
+        FreeCADGui.doCommand('obj=EM.makeVHSolver()')
+        FreeCAD.ActiveDocument.commitTransaction()
+        FreeCAD.ActiveDocument.recompute()
+
+class _CommandVHVoxelizeAll:
+    ''' The EM VoxHenry 'voxelize all' command definition
+'''
+    def GetResources(self):
+        return {'Pixmap'  : os.path.join(iconPath, 'EM_VHVoxelizeAll.svg') ,
+                'MenuText': QT_TRANSLATE_NOOP("EM_VHVoxelizeAll","VHVoxelizeAll"),
+                'Accel': "E, W",
+                'ToolTip': QT_TRANSLATE_NOOP("EM_VHVoxelizeAll","Voxelize all the VHConductors and VHPorts in the document")}
+                
+    def IsActive(self):
+        return not FreeCAD.ActiveDocument is None
+
+    def Activated(self):
+        # preferences
+        #p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/EM")
+        #self.Width = p.GetFloat("Width",200)
+        # get the selected object(s)
+        if FreeCAD.ActiveDocument is not None:
+            if hasattr(FreeCAD.ActiveDocument, 'VHSolver'):
+                FreeCAD.ActiveDocument.openTransaction(translate("EM","Voxelize all VHConductors and VHPorts"))
+                FreeCADGui.addModule("EM")
+                FreeCADGui.doCommand('FreeCAD.ActiveDocument.VHSolver.Proxy.voxelizeAll()')
+                FreeCAD.ActiveDocument.commitTransaction()
+                # recompute the document (assuming something has changed; otherwise this is dummy)
+                FreeCAD.ActiveDocument.recompute()
+
+if FreeCAD.GuiUp:
+    FreeCADGui.addCommand('EM_VHSolver',_CommandVHSolver())
+    FreeCADGui.addCommand('EM_VHVoxelizeAll',_CommandVHVoxelizeAll())

Export_mesh.py

@@ -155,6 +155,8 @@ def export_faces(filename, isDiel=False, name="", showNormals=False, forceMesh=F
         a reference point to each panel to indicate which is the external side (outside)
     'name' is the name of the conductor created in the file. If not specified, defaults
         to the label of the first element in the selection set
+    'forceMesh' force the meshing of all faces, even if they could be exported non-meshed
+        (triangular or quadrilateral faces).
     'showNormals' will add a compound object composed by a set of arrows showing the 
         normal direction for each panel
     'folder' is the folder in which 'filename' will be saved
@@ -203,7 +205,7 @@ def export_faces(filename, isDiel=False, name="", showNormals=False, forceMesh=F
     for face in facesSimple:
         sortEdges = Part.__sortEdges__(face.Edges)
         # Point of a Vertex is a Vector, as well as Face.normalAt()
-        points = [x.Vertexes[0].Point for x in sortEdges]
+        points = [x.firstVertex().Point for x in sortEdges]
         panels.append( [points, face.normalAt(0,0)] )
     for facet in facets:
         points = [ Vector(x) for x in facet.Points]

InitGui.py

@@ -45,8 +45,7 @@ class EMWorkbench(Workbench):
         self.emtools = ["EM_About"]
         self.emfhtools = ["EM_FHSolver", "EM_FHNode", "EM_FHSegment", "EM_FHPath", "EM_FHPlane",
                 "EM_FHPlaneHole", "EM_FHPlaneAddRemoveNodeHole", "EM_FHEquiv", "EM_FHPort", "EM_FHInputFile"]
-        #self.emvhtools = ["EM_VHSolver"]
-        self.emvhtools = []
+        self.emvhtools = ["EM_VHSolver", "EM_VHConductor", "EM_VHPort", "EM_VHCondPortVoxelize", "EM_VHVoxelizeAll", "EM_VHInputFile"]
         # draft tools
         # setup menus
         self.draftcmdList = ["Draft_Line","Draft_Rectangle"]
@@ -63,7 +62,7 @@ class EMWorkbench(Workbench):
 
         def QT_TRANSLATE_NOOP(scope, text): return text
         self.appendToolbar(QT_TRANSLATE_NOOP("Workbench","E.M. FastHenry tools"),self.emfhtools)
-        #self.appendToolbar(QT_TRANSLATE_NOOP("Workbench","E.M. VoxHenry tools"),self.emvhtools)
+        self.appendToolbar(QT_TRANSLATE_NOOP("Workbench","E.M. VoxHenry tools"),self.emvhtools)
         self.appendToolbar(QT_TRANSLATE_NOOP("Workbench","Draft creation tools"),self.draftcmdList)
         self.appendToolbar(QT_TRANSLATE_NOOP("Workbench","Draft mod tools"),self.draftmodtools)
         self.appendMenu(QT_TRANSLATE_NOOP("EM","&EM"),self.emfhtools + self.emvhtools + self.emtools)

Resources/EM_FCSolver.svg

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Resources/EM_FHInputFile.svg

@@ -107,6 +107,26 @@
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        xlink:href="#linearGradient3138"
        inkscape:collect="always" />
+    <linearGradient
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@@ -231,5 +251,25 @@
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export_to_FastHenry.py

@@ -296,13 +296,6 @@ def export_segs2(filename="", disc=3, custDot="", FHbug=False, breakSeg=False, w
                 
             # sort the edges. If the selected path is disconnected, the path will be broken!
             edges = Part.__sortEdges__(edges_raw)           
-            # TBC: join parts with additional edges, or .equiv-ing them, using distToShape between the obj.Shape
-            #      Can happen with a compound containing different edges / wires / stetches
-            #edge = Part.Edge(Part.Line(Vector(154.0002, -62.6872,0), Vector(154.0002,-53.1876,0)))
-            #v = Part.Vertex(edges[0].Curve.StartPoint)
-            #v.Tolerance
-            #App.ActiveDocument.Shape.Shape.Vertexes[1].distToShape(App.ActiveDocument.Shape001.Shape.Vertexes[0])
-            
             # scan edges and derive nodes
             nodes = []
             for edge in edges: