New recipe to fix dense TINs from 12D loading properly in Revit

src/ifcpatch/ifcpatch/recipes/Fix12DToRevitTINs.py

@@ -0,0 +1,63 @@
+class Patcher:
+    def __init__(self, src, file, logger, args=None):
+        self.src = src
+        self.file = file
+        self.logger = logger
+        self.args = args
+
+    def patch(self):
+        # TINs exported from 12D may contain dense or highly obtuse triangles.
+        # Although these will load in Revit, you will not be able to use Revit's
+        # Spot Coordinate or Spot Elevation tool.
+        #
+        # See bug: https://github.com/Autodesk/revit-ifc/issues/511
+        #
+        # The solution will merge vertices closer than 10mm to prevent dense
+        # portions of the TIN at a minor sacrifice of surveying accuracy. It
+        # will also triangulate all meshes to prevent non-coplanar surfaces, and
+        # delete any obtuse triangles where one of their angles is less than 0.3
+        # degrees. Therefore the result will contain some minor "holes" in the
+        # TIN, but these holes will only be in dense triangles that Revit can't
+        # handle anyway and won't affect most coordination tasks.
+        #
+        # This patch is designed to only work on 12D IFC exports. It also
+        # requires you to run it using Blender, as the geometric modification
+        # uses the Blender geometry engine.
+        import bpy
+        import bmesh
+        import blenderbim.tool as tool
+        from math import degrees
+
+        bpy.ops.bim.load_project(filepath=self.src)
+
+        old_history_size = tool.Ifc.get().history_size
+        old_undo_steps = bpy.context.preferences.edit.undo_steps
+        tool.Ifc.get().history_size = 0
+        bpy.context.preferences.edit.undo_steps = 0
+
+        angle_threshold = 0.3
+
+        for obj in bpy.data.objects:
+            if not obj.BIMObjectProperties.ifc_definition_id or not obj.data:
+                continue
+            data = obj.data
+            bm = bmesh.new()
+            bm.from_mesh(data)
+            bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=0.01)
+            bmesh.ops.triangulate(bm, faces=bm.faces[:], quad_method='BEAUTY', ngon_method='BEAUTY')
+            bm.faces.ensure_lookup_table()
+            for polygon in bm.faces:
+                v1, v2, v3 = [v.co for v in polygon.verts]
+                d1 = degrees((v2-v1).angle(v3-v1))
+                d2 = degrees((v3-v2).angle(v1-v2))
+                d3 = degrees((v1-v3).angle(v2-v3))
+                if d1 < angle_threshold or d2 < angle_threshold or d3 < angle_threshold:
+                    bm.faces.remove(polygon)
+            bm.to_mesh(data)
+            bm.free()
+            bpy.ops.bim.update_representation(obj=obj.name, ifc_representation_class="")
+
+        tool.Ifc.get().history_size = old_history_size
+        bpy.context.preferences.edit.undo_steps = old_undo_steps
+
+        self.file = tool.Ifc.get()