Autodetect dense meshes to make it faster when loading so users don't need to go into advanced mode.

src/blenderbim/blenderbim/bim/import_ifc.py

@@ -146,12 +146,15 @@ class MaterialCreator:
         faces_remap = None
         texture_map = None
         if coordinates.is_a("IfcIndexedPolygonalTextureMap"):
-            faces_remap = [[coordinates_remap[i-1] for i in tex_coord_index.TexCoordsOf.CoordIndex]
+            faces_remap = [
-                        for tex_coord_index in coordinates.TexCoordIndices]
+                [coordinates_remap[i - 1] for i in tex_coord_index.TexCoordsOf.CoordIndex]
+                for tex_coord_index in coordinates.TexCoordIndices
+            ]
             texture_map = [tex_coord_index.TexCoordIndex for tex_coord_index in coordinates.TexCoordIndices]
         elif coordinates.is_a("IfcIndexedTriangleTextureMap"):
-            faces_remap = [[coordinates_remap[i-1] for i in triangle_face]
+            faces_remap = [
-                        for triangle_face in coordinates.MappedTo.CoordIndex]
+                [coordinates_remap[i - 1] for i in triangle_face] for triangle_face in coordinates.MappedTo.CoordIndex
+            ]
             texture_map = coordinates.TexCoordIndex
 
         # apply uv to each face
@@ -166,7 +169,7 @@ class MaterialCreator:
             )
             # apply uv to each loop
             for loop, i in zip(bface.loops, texCoordIndex):
-                loop[uv_layer].uv = coordinates.TexCoords.TexCoordsList[i-1]
+                loop[uv_layer].uv = coordinates.TexCoords.TexCoordsList[i - 1]
 
         # Finish up, write the bmesh back to the mesh
         bm.to_mesh(self.mesh)
@@ -263,6 +266,8 @@ class IfcImporter:
         self.profile_code("Calculate unit scale")
         self.calculate_model_offset()
         self.profile_code("Calculate model offset")
+        self.predict_dense_mesh()
+        self.profile_code("Predict dense mesh")
         self.set_units()
         self.profile_code("Set units")
         self.create_project()
@@ -348,6 +353,7 @@ class IfcImporter:
             )
         if self.body_contexts:
             self.settings.set_context_ids(self.body_contexts)
+            self.settings_body_2d.set_context_ids(self.body_contexts)
         # Annotation ContextType is to accommodate broken Revit files
         # See https://github.com/Autodesk/revit-ifc/issues/187
         self.plan_contexts = [
@@ -498,6 +504,26 @@ class IfcImporter:
                         products.extend(self.get_products_from_shape_representation(inverse_element))
         return products
 
+    def predict_dense_mesh(self):
+        threshold = 10000  # Just from experience.
+
+        faces = [len(e.CfsFaces) for e in self.file.by_type("IfcClosedShell")]
+        if faces and max(faces) > threshold:
+            self.ifc_import_settings.should_use_native_meshes = True
+            return
+
+        if self.file.schema == "IFC2X3":
+            return
+
+        faces = [len(e.Faces) for e in self.file.by_type("IfcPolygonalFaceSet")]
+        if faces and max(faces) > threshold:
+            self.ifc_import_settings.should_use_native_meshes = True
+            return
+
+        faces = [len(e.CoordIndex) for e in self.file.by_type("IfcTriangulatedFaceSet")]
+        if faces and max(faces) > threshold:
+            self.ifc_import_settings.should_use_native_meshes = True
+
     def calculate_model_offset(self):
         props = bpy.context.scene.BIMGeoreferenceProperties
         if props.has_blender_offset: