Use shallow copy for arraying

Boost performance. Experimental.

lattice2BaseFeature.py

@@ -141,17 +141,17 @@ class LatticeFeature():
                     obj.Placement = App.Placement()
             
             if bExposing:
-                obj.Shape = marker.copy()
+                obj.Shape = shallow_copy(marker)
                 obj.Placement = plms[0]
             else:
                 for plm in plms:
-                    sh = marker.copy()
+                    sh = shallow_copy(marker)
                     sh.Placement = plm
                     shapes.append(sh)
                     
                 if len(shapes) == 0:
                     obj.Shape = lattice2Markers.getNullShapeShape(markerSize)
-                    raise ValueError('Lattice object is null') #Feeding empty compounds to FreeCAD seems to cause rendering issues, otherwise it would have been a good idea to output nothing.
+                    raise ValueError('Lattice object is null') 
                 
                 sh = Part.makeCompound(shapes)
                 obj.Shape = sh

lattice2Common.py

@@ -81,6 +81,23 @@ def deselect(sel):
     for selobj in sel:
         FreeCADGui.Selection.removeSelection(selobj.Object)
         
+def shallow_copy(shape):
+    copiers = {
+      "Vertex": lambda(sh): sh.Vertexes[0],
+      "Edge": lambda(sh): sh.Edges[0],
+      "Wire": lambda(sh): sh.Wires[0],
+      "Face": lambda(sh): sh.Faces[0],
+      "Shell": lambda(sh): sh.Shells[0],
+      "Solid": lambda(sh): sh.Solids[0],
+      "CompSolid": lambda(sh): sh.CompSolids[0],
+      "Compound": lambda(sh): sh.Compounds[0],
+      }
+    copier = copiers.get(shape.ShapeType)
+    if copier is None:
+        copier = lambda(sh): sh.copy()
+        FreeCAD.Console.PrintWarning("Lattice2: shallow_copy: unexpected shape type '{typ}'. Using deep copy instead.\n".format(typ= shape.ShapeType))
+    return copier(shape)
+
 # OCC's Precision::Confusion; should have taken this from FreeCAD but haven't found; unlikely to ever change.
 DistConfusion = 1e-7
 ParaConfusion = 1e-8

lattice2PopulateChildren.py

@@ -106,7 +106,7 @@ class LatticePopulateChildren(lattice2BaseFeature.LatticeFeature):
                 objectPlm = objectPlms[iChild]
                 outputPlms.append(plm.multiply(objectPlm))
             else:
-                outputShape = objectShapes[iChild].copy()
+                outputShape = shallow_copy(objectShapes[iChild])
                 outputShape.Placement = plm.multiply(outputShape.Placement)
                 outputShapes.append(outputShape)
             

lattice2PopulateCopies.py

@@ -127,7 +127,7 @@ class LatticePopulateCopies(lattice2BaseFeature.LatticeFeature):
                 for objectPlm in objectPlms:
                     outputPlms.append(plm.multiply(objectPlm))
             else:
-                outputShape = objectShape.copy()
+                outputShape = shallow_copy(objectShape)
                 outputShape.Placement = plm.multiply(outputShape.Placement)
                 outputShapes.append(outputShape)