From e7d16c5f620bc4ddded8b8eae97d6e29c0012490 Mon Sep 17 00:00:00 2001
From: Yorik van Havre <yorik@uncreated.net>
Date: Wed, 28 Oct 2015 17:24:43 -0200
Subject: [PATCH] Arch: added IFC export preference option to choose
 triangulation style for non-planar shapes

---
 src/Mod/Arch/Resources/ui/preferences-ifc.ui | 20 ++++++++++++
 src/Mod/Arch/importIFC.py                    | 32 +++++++++++---------
 2 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/src/Mod/Arch/Resources/ui/preferences-ifc.ui b/src/Mod/Arch/Resources/ui/preferences-ifc.ui
index a66584aa01..2f88dbfc17 100644
--- a/src/Mod/Arch/Resources/ui/preferences-ifc.ui
+++ b/src/Mod/Arch/Resources/ui/preferences-ifc.ui
@@ -314,6 +314,26 @@
         </item>
        </layout>
       </item>
+      <item>
+       <layout class="QHBoxLayout" name="horizontalLayout_8">
+        <item>
+         <widget class="Gui::PrefCheckBox" name="checkBox_4">
+          <property name="toolTip">
+           <string>Curved shapes that cannot be represented as curves in IFC are decomposed into flat facets. If this is checked, simple triangulation will be used, otherwise some additional calculation is done to join coplanar facets.</string>
+          </property>
+          <property name="text">
+           <string>Use classic triangulation</string>
+          </property>
+          <property name="prefEntry" stdset="0">
+           <cstring>ifcClassicTriangulation</cstring>
+          </property>
+          <property name="prefPath" stdset="0">
+           <cstring>Mod/Arch</cstring>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </item>
      </layout>
     </widget>
    </item>
diff --git a/src/Mod/Arch/importIFC.py b/src/Mod/Arch/importIFC.py
index 8c44078d42..0ff51df544 100644
--- a/src/Mod/Arch/importIFC.py
+++ b/src/Mod/Arch/importIFC.py
@@ -1175,6 +1175,7 @@ def getRepresentation(ifcfile,context,obj,forcebrep=False,subtraction=False,tess
                 fcsolid.scale(0.001) # to meters
                 faces = []
                 curves = False
+                shapetype = "brep"
                 for fcface in fcsolid.Faces:
                     for e in fcface.Edges:
                         if not isinstance(e.Curve,Part.Line):
@@ -1182,17 +1183,19 @@ def getRepresentation(ifcfile,context,obj,forcebrep=False,subtraction=False,tess
                                 curves = True
                                 break
                 if curves:
-                    #shapetype = "triangulated"
-                    #tris = fcsolid.tessellate(tessellation)
-                    #for tri in tris[1]:
-                    #    pts =   [ifcfile.createIfcCartesianPoint(tuple(tris[0][i])) for i in tri]
-                    #    loop =  ifcfile.createIfcPolyLoop(pts)
-                    #    bound = ifcfile.createIfcFaceOuterBound(loop,True)
-                    #    face =  ifcfile.createIfcFace([bound])
-                    #    faces.append(face)
-                    fcsolid = Arch.removeCurves(fcsolid)
-
-                shapetype = "brep"
+                    if FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Arch").GetBool("ifcClassicTriangulation",False):
+                        shapetype = "triangulated"
+                        tris = fcsolid.tessellate(tessellation)
+                        for tri in tris[1]:
+                            pts =   [ifcfile.createIfcCartesianPoint(tuple(tris[0][i])) for i in tri]
+                            loop =  ifcfile.createIfcPolyLoop(pts)
+                            bound = ifcfile.createIfcFaceOuterBound(loop,True)
+                            face =  ifcfile.createIfcFace([bound])
+                            faces.append(face)
+                            fcsolid = Part.Shape() # empty shape so below code is not executed
+                    else:
+                        fcsolid = Arch.removeCurves(fcsolid)
+                    
                 for fcface in fcsolid.Faces:
                     loops = []
                     verts = [v.Point for v in Part.Wire(Part.__sortEdges__(fcface.OuterWire.Edges)).Vertexes]
@@ -1220,9 +1223,10 @@ def getRepresentation(ifcfile,context,obj,forcebrep=False,subtraction=False,tess
                     face =  ifcfile.createIfcFace(loops)
                     faces.append(face)
 
-                shell = ifcfile.createIfcClosedShell(faces)
-                shape = ifcfile.createIfcFacetedBrep(shell)
-                shapes.append(shape)
+                if faces:
+                    shell = ifcfile.createIfcClosedShell(faces)
+                    shape = ifcfile.createIfcFacetedBrep(shell)
+                    shapes.append(shape)
 
     if shapes: