From b9723c08e47aa95c6b4c35af1d0afc18ab8b3bf2 Mon Sep 17 00:00:00 2001
From: s-leger <stephen@3dservices.ch>
Date: Mon, 24 May 2021 00:19:39 +0200
Subject: [PATCH] Ensure polygons are always coplanar (#1482)

* Ensure polygons are always coplanar

fix #1481
May adopt a bmesh approach instead ?

* Ensure polygons are coplanar

The bmesh version is lot faster than modifier one
---
 .../api/geometry/add_representation.py        | 33 +++++++++++--------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py b/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py
index 2c439ba2e9..26c844bffc 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/geometry/add_representation.py
@@ -44,29 +44,36 @@ class Usecase:
         return self.create_variable_representation()
 
     def evaluate_geometry(self):
-        self.boolean_modifiers = []
+        
         for modifier in self.settings["blender_object"].modifiers:
             if modifier.type == "BOOLEAN":
                 modifier.show_viewport = False
+        
+        mesh = self.settings["blender_object"].evaluated_get(bpy.context.evaluated_depsgraph_get()).to_mesh()
+        bm = bmesh.new()
+        bm.from_mesh(mesh)
+        bmesh.ops.triangulate(bm, faces=bm.faces)
 
-        if self.settings["should_force_triangulation"]:
-            mesh = self.settings["blender_object"].evaluated_get(bpy.context.evaluated_depsgraph_get()).to_mesh()
-            bm = bmesh.new()
-            bm.from_mesh(mesh)
-            bmesh.ops.triangulate(bm, faces=bm.faces)
-            bm.to_mesh(mesh)
-            bm.free()
-            del bm
-            self.settings["geometry"] = mesh
-        else:
-            self.settings["geometry"] = (
-                self.settings["blender_object"].evaluated_get(bpy.context.evaluated_depsgraph_get()).to_mesh()
+        if not self.settings["should_force_triangulation"]:
+            bmesh.ops.dissolve_limit(
+                bm,
+                angle_limit=0.00174533,
+                use_dissolve_boundaries=False,
+                verts=bm.verts[:],
+                edges=bm.edges[:],
+                delimit={'MATERIAL'}
             )
+        bm.to_mesh(mesh)
+        bm.free()
+        del bm
 
+        self.settings["geometry"] = mesh
+        
         for modifier in self.settings["blender_object"].modifiers:
             if modifier.type == "BOOLEAN":
                 modifier.show_viewport = True
 
+                
     def create_model_representation(self):
         if self.settings["context"].is_a() == "IfcGeometricRepresentationContext":
             return self.create_variable_representation()