Fix #1585. Materials are added as a potential if you assign it as an object material too, for convenience.

src/blenderbim/blenderbim/bim/import_ifc.py

@@ -54,11 +54,11 @@ class MaterialCreator:
         if not self.mesh or self.mesh.name in self.parsed_meshes:
             return
         self.parsed_meshes.add(self.mesh.name)
-        self.add_default_material_surface_style(element)
+        self.add_default_material(element)
         if self.parse_representations(element):
             self.assign_material_slots_to_faces()
 
-    def add_default_material_surface_style(self, element):
+    def add_default_material(self, element):
         element_material = ifcopenshell.util.element.get_material(element)
         if not element_material:
             return
@@ -71,6 +71,10 @@ class MaterialCreator:
             if surface_style:
                 self.mesh.materials.append(self.styles[surface_style[0].id()])
                 return
+        # For authoring convenience, we choose to assign a material, even if it has no surface style. See #1585.
+        for material in [m for m in self.ifc_importer.file.traverse(element_material) if m.is_a("IfcMaterial")]:
+            self.mesh.materials.append(self.materials[material.id()])
+            return
 
     def load_existing_materials(self):
         for material in bpy.data.materials:

src/blenderbim/blenderbim/bim/module/material/operator.py

@@ -1,6 +1,7 @@
 import bpy
 import json
 import ifcopenshell.api
+import ifcopenshell.util.element
 import ifcopenshell.util.attribute
 import ifcopenshell.util.representation
 import blenderbim.bim.helper
@@ -54,14 +55,19 @@ class AddMaterial(bpy.types.Operator):
         self.file = IfcStore.get_file()
         result = ifcopenshell.api.run("material.add_material", self.file, **{"name": obj.name})
         obj.BIMObjectProperties.ifc_definition_id = result.id()
+        IfcStore.link_element(result, obj)
         if obj.BIMMaterialProperties.ifc_style_id:
             context = ifcopenshell.util.representation.get_context(self.file, "Model", "Body", "MODEL_VIEW")
             if context:
-                ifcopenshell.api.run("style.assign_material_style", self.file, **{
-                    "material": result,
-                    "style": self.file.by_id(obj.BIMMaterialProperties.ifc_style_id),
-                    "context": context,
-                })
+                ifcopenshell.api.run(
+                    "style.assign_material_style",
+                    self.file,
+                    **{
+                        "material": result,
+                        "style": self.file.by_id(obj.BIMMaterialProperties.ifc_style_id),
+                        "context": context,
+                    },
+                )
         Data.load(IfcStore.get_file())
         material_prop_purge()
         return {"FINISHED"}
@@ -103,19 +109,37 @@ class AssignMaterial(bpy.types.Operator):
         obj = bpy.data.objects.get(self.obj) if self.obj else bpy.context.active_object
         material_type = self.material_type or obj.BIMObjectMaterialProperties.material_type
         self.file = IfcStore.get_file()
+        element = self.file.by_id(obj.BIMObjectProperties.ifc_definition_id)
         ifcopenshell.api.run(
             "material.assign_material",
             self.file,
             **{
-                "product": self.file.by_id(obj.BIMObjectProperties.ifc_definition_id),
+                "product": element,
                 "type": material_type,
                 "material": self.file.by_id(int(obj.BIMObjectMaterialProperties.material)),
             },
         )
         Data.load(IfcStore.get_file())
         Data.load(IfcStore.get_file(), obj.BIMObjectProperties.ifc_definition_id)
+        self.set_default_material(obj, element)
         return {"FINISHED"}
 
+    def set_default_material(self, obj, element):
+        element_material = ifcopenshell.util.element.get_material(element)
+        material = [m for m in self.file.traverse(element_material) if m.is_a("IfcMaterial")]
+        if not material:
+            return
+
+        object_material_ids = [
+            om.BIMObjectProperties.ifc_definition_id
+            for om in obj.data.materials
+            if om is not None and om.BIMObjectProperties.ifc_definition_id
+        ]
+
+        if material[0].id() in object_material_ids:
+            return
+        obj.data.materials.append(IfcStore.get_element(material[0].id()))
+
 
 class UnassignMaterial(bpy.types.Operator):
     bl_idname = "bim.unassign_material"
@@ -523,8 +547,25 @@ class EditAssignedMaterial(bpy.types.Operator):
         elif material_set.is_a("IfcMaterialProfileSet"):
             Data.load_profiles()
         bpy.ops.bim.disable_editing_assigned_material(obj=obj.name)
+        self.set_default_material(obj, self.file.by_id(obj.BIMObjectProperties.ifc_definition_id))
         return {"FINISHED"}
 
+    def set_default_material(self, obj, element):
+        element_material = ifcopenshell.util.element.get_material(element)
+        material = [m for m in self.file.traverse(element_material) if m.is_a("IfcMaterial")]
+        if not material:
+            return
+
+        object_material_ids = [
+            om.BIMObjectProperties.ifc_definition_id
+            for om in obj.data.materials
+            if om is not None and om.BIMObjectProperties.ifc_definition_id
+        ]
+
+        if material[0].id() in object_material_ids:
+            return
+        obj.data.materials.append(IfcStore.get_element(material[0].id()))
+
 
 class EnableEditingMaterialSetItem(bpy.types.Operator):
     bl_idname = "bim.enable_editing_material_set_item"