adding tessellation to ellipses and adding a user parameter for line

segment length of ellipses and splines with a Shape2DView projection.
This will make it useful for DXF output.

src/Mod/Draft/Draft.py

@@ -4174,11 +4174,13 @@ class _Shape2DView(_DraftObject):
         obj.addProperty("App::PropertyEnumeration","ProjectionMode","Draft","The way the viewed object must be projected")
         obj.addProperty("App::PropertyIntegerList","FaceNumbers","Draft","The indices of the faces to be projected in Individual Faces mode")
         obj.addProperty("App::PropertyBool","HiddenLines","Draft","Show hidden lines")
-        obj.addProperty("App::PropertyBool","Tessellation","Draft","Tessellate BSplines into line segments using number of spline poles")
+        obj.addProperty("App::PropertyBool","Tessellation","Draft","Tessellate Ellipses and BSplines into line segments")
+        obj.addProperty("App::PropertyFloat","SegmentLength","Draft","Length of line segments if tessellating Ellipses or BSplines into line segments")
         obj.Projection = Vector(0,0,1)
         obj.ProjectionMode = ["Solid","Individual Faces","Cutlines","Cutfaces"]
         obj.HiddenLines = False
         obj.Tessellation = True
+        obj.SegmentLength = .05
         _DraftObject.__init__(self,obj,"Shape2DView")
 
     def getProjected(self,obj,shape,direction):
@@ -4193,10 +4195,11 @@ class _Shape2DView(_DraftObject):
             if obj.HiddenLines:
                 for g in groups[5:]:
                     edges.append(g)
-        return Part.makeCompound(edges)
-        #if hasattr(obj,"Tessellation"):
-            #return DraftGeomUtils.cleanProjection(Part.makeCompound(edges),obj.Tessellation)
-        #else:
+        #return Part.makeCompound(edges)
+        if hasattr(obj,"Tessellation"):
+            return DraftGeomUtils.cleanProjection(Part.makeCompound(edges),obj.Tessellation,obj.SegmentLength)
+        else:
+            return Part.makeCompound(edges)
             #return DraftGeomUtils.cleanProjection(Part.makeCompound(edges))
 
     def execute(self,obj):

src/Mod/Draft/DraftGeomUtils.py

@@ -1808,10 +1808,12 @@ def curvetowire(obj,steps):
         p0 = p
     return edgelist
 
-def cleanProjection(shape,tessellate=False):
+def cleanProjection(shape,tessellate=True,seglength=.05):
     "returns a valid compound of edges, by recreating them"
     # this is because the projection algorithm somehow creates wrong shapes.
     # they dispay fine, but on loading the file the shape is invalid
+    # Now with tanderson's fix to ProjectionAlgos, that isn't the case, but this
+    # can be used for tessellating ellipses and splines for DXF output-DF
     oldedges = shape.Edges
     newedges = []
     for e in oldedges:
@@ -1826,15 +1828,18 @@ def cleanProjection(shape,tessellate=False):
                 else:
                     newedges.append(e.Curve.toShape())
             elif geomType(e) == "Ellipse":
-                if len(e.Vertexes) > 1:
-                    a = Part.Arc(e.Curve,e.FirstParameter,e.LastParameter).toShape()
-                    newedges.append(a)
+                if tessellate:
+                    newedges.append(Part.Wire(curvetowire(e, seglength)))
                 else:
-                    newedges.append(e.Curve.toShape())
+                    if len(e.Vertexes) > 1:
+                        a = Part.Arc(e.Curve,e.FirstParameter,e.LastParameter).toShape()
+                        newedges.append(a)
+                    else:
+                        newedges.append(e.Curve.toShape())
             elif geomType(e) == "BSplineCurve" or \
                  geomType(e) == "BezierCurve":
                 if tessellate:
-                    newedges.append(Part.Wire(curvetowire(e,e.Curve.NbPoles)))
+                    newedges.append(Part.Wire(curvetowire(e,seglength)))
                 else:
                     if isLine(e.Curve):
                         l = Part.Line(e.Vertexes[0].Point,e.Vertexes[-1].Point).toShape()
@@ -1847,6 +1852,36 @@ def cleanProjection(shape,tessellate=False):
             print "Debug: error cleaning edge ",e
     return Part.makeCompound(newedges)
     
+def curvetosegment(curve,seglen):
+    points = curve.discretize(seglen)
+    p0 = points[0]
+    edgelist = []
+    for p in points[1:]:
+        edge = Part.makeLine((p0.x,p0.y,p0.z),(p.x,p.y,p.z))
+        edgelist.append(edge)
+        p0 = p
+    return edgelist
+
+def tessellateProjection(shape,seglen):
+    ''' Returns projection with BSplines and Ellipses broken into line segments.
+        Useful for exporting projected views to *dxf files.'''
+    oldedges = shape.Edges
+    newedges = []
+    for e in oldedges:
+        try:
+            if geomType(e) == "Line":
+                newedges.append(e.Curve.toShape())
+            elif geomType(e) == "Circle":
+                newedges.append(e.Curve.toShape())
+            elif geomType(e) == "Ellipse":
+                newedges.append(Part.Wire(curvetosegment(e,seglen)))
+            elif geomType(e) == "BSplineCurve":
+                newedges.append(Part.Wire(curvetosegment(e,seglen)))
+            else:
+                newedges.append(e)
+        except:
+            print "Debug: error cleaning edge ",e
+    return Part.makeCompound(newedges)
 
 # circle functions *********************************************************