Presentation layers are now assigned to meshes, and implement representation assignment. See #1109.

src/ifcblenderexport/blenderbim/bim/export_ifc.py

@@ -974,11 +974,11 @@ class IfcParser:
 
     def load_presentation_layer_assignments(self):
         for representation in self.representations.values():
-            if representation["presentation_layer"]:
+            if representation["presentation_layer"] is False:
-                layer = representation["presentation_layer"]
+                continue
-                if layer.name == "":
+            self.presentation_layer_assignments.setdefault(representation["presentation_layer"], []).append(
-                    continue
+                representation
-                self.presentation_layer_assignments.setdefault(layer.name, []).append(representation)
+            )
 
     def load_representations(self):
         if not self.ifc_export_settings.has_representations:
@@ -1110,9 +1110,9 @@ class IfcParser:
             "is_native": mesh.BIMMeshProperties.is_native if hasattr(mesh, "BIMMeshProperties") else False,
             "is_swept_solid": mesh.BIMMeshProperties.is_swept_solid if hasattr(mesh, "BIMMeshProperties") else False,
             "is_generated": False,
-            "presentation_layer": obj.BIMObjectProperties.presentation_layer
+            "presentation_layer": mesh.BIMMeshProperties.presentation_layer_index
-            if hasattr(obj, "BIMObjectProperties")
+            if hasattr(mesh, "BIMMeshProperties") and mesh.BIMMeshProperties.presentation_layer_index != -1
-            else None,
+            else False,
             "attributes": {"Name": mesh.name},
         }
 
@@ -1163,7 +1163,6 @@ class IfcParser:
             "raw": material,
             "attributes": self.get_material_attributes(material),
         }
-        print(material.name)
         self.materials[material.name] = data
         self.get_material_psets(data, material)
 
@@ -1662,7 +1661,6 @@ class IfcExporter:
             if not properties:
                 continue
             pset["attributes"].update({"Properties": properties, "Material": pset["material"]["ifc"]})
-            print(pset["attributes"])
             pset["ifc"] = self.file.create_entity("IfcMaterialProperties", **pset["attributes"])
 
     def create_qto_properties(self, qto):
@@ -2034,28 +2032,22 @@ class IfcExporter:
         return self.file.createIfcStyledItem(representation_item, [surface_style], item["attributes"]["Name"])
 
     def create_presentation_layer_assignments(self):
-        scene_props = bpy.context.scene.BIMProperties
+        for layer_index, representations in self.ifc_parser.presentation_layer_assignments.items():
-        for name, assigned_items in self.ifc_parser.presentation_layer_assignments.items():
+            layer = bpy.context.scene.BIMProperties.presentation_layers[int(layer_index)]
-            if name == "":
+            assigned_items = []
-                continue
+            for representation in representations:
-            layer = scene_props.presentation_layers[name]
+                for usage in representation["ifc"].MapUsage:
-
+                    for inverse in self.file.get_inverse(usage):
-            with_style = False
+                        assigned_items.append(inverse)
-            if layer.layer_on is False:
+            if layer.layer_on:
-                with_style = True
-
-            if with_style is False:
                 self.file.createIfcPresentationLayerAssignment(
-                    name,
+                    layer.name, layer.description or None, assigned_items, layer.identifier or None,
-                    layer.description or None,
-                    [i["ifc"].MappedRepresentation for i in assigned_items],
-                    layer.identifier or None,
                 )
             else:
                 self.file.createIfcPresentationLayerWithStyle(
-                    name,
+                    layer.name,
                     layer.description or None,
-                    [i["ifc"].MappedRepresentation for i in assigned_items],
+                    assigned_items,
                     layer.identifier or None,
                     layer.layer_on,
                     layer.layer_frozen,

src/ifcblenderexport/blenderbim/bim/import_ifc.py

@@ -479,8 +479,8 @@ class IfcImporter:
             self.profile_code("Merging by colour")
         self.add_project_to_scene()
         self.profile_code("Add project to scene")
-        self.get_presentation_layers()
+        self.create_presentation_layers()
-        self.profile_code("Get presentation layers")
+        self.profile_code("Create presentation layers")
         if self.ifc_import_settings.should_clean_mesh and len(self.file.by_type("IfcElement")) < 10000:
             self.clean_mesh()
             self.profile_code("Mesh cleaning")
@@ -1328,9 +1328,10 @@ class IfcImporter:
             self.type_collection.name
         ].hide_viewport = True
 
-    def get_presentation_layers(self):
+    def create_presentation_layers(self):
         for assignment in self.file.by_type("IfcPresentationLayerAssignment"):
             layer = bpy.context.scene.BIMProperties.presentation_layers.add()
+            layer_index = len(bpy.context.scene.BIMProperties.presentation_layers) - 1
             layer.name = assignment.Name
             layer.description = assignment.Description or ""
             layer.identifier = assignment.Identifier or ""
@@ -1340,19 +1341,18 @@ class IfcImporter:
                 layer.layer_blocked = assignment.LayerBlocked if assignment.LayerBlocked is not None else False
 
             for item in assignment.AssignedItems:
-                # TODO: This is a simplified and incorrect implementation of assigning presentation layers to objects
+                # TODO: This is a simplified implementation of assigning presentation layers that ignores assigned
-                # themselves, and will need to be rewritten in the future. See bug #1109. This code also does not
+                # representation items, does not consider mapped representations, and assumes a Body context. See #1109.
-                # consider mapped representations.
                 guids = []
-                if not hasattr(item, "OfProductRepresentation"):
+                if not hasattr(item, "OfProductRepresentation") or item.RepresentationIdentifier != "Body":
-                    continue  # TODO: At the moment we ignore representation items
+                    continue
                 for product_representation in item.OfProductRepresentation:
                     for product in product_representation.ShapeOfProduct:
                         guids.append(product.GlobalId)
                 for obj in bpy.context.selectable_objects:
                     global_id = obj.BIMObjectProperties.attributes.get("GlobalId")
                     if global_id and global_id.string_value in guids:
-                        obj.BIMObjectProperties.presentation_layer.name = layer.name
+                        obj.data.BIMMeshProperties.presentation_layer_index = layer_index
                         obj.hide_set(not layer.layer_on)
 
     def clean_mesh(self):

src/ifcblenderexport/blenderbim/bim/operator.py

@@ -4328,11 +4328,12 @@ class AssignPresentationLayer(bpy.types.Operator):
     index: bpy.props.IntProperty()
 
     def execute(self, context):
-        presentation_layer = bpy.context.scene.BIMProperties.presentation_layers[self.index]
+        layer = bpy.context.scene.BIMProperties.presentation_layers[self.index]
         for obj in bpy.context.selected_objects:
-            # TODO: assign using a different strategy than name association
+            if not obj.data or not hasattr(obj.data, "BIMMeshProperties"):
-            obj.BIMObjectProperties.presentation_layer.name = presentation_layer.name
+                continue
-            obj.hide_set(not presentation_layer.layer_on)
+            obj.data.BIMMeshProperties.presentation_layer_index = self.index
+            obj.hide_set(not layer.layer_on)
         return {"FINISHED"}
 
 
@@ -4341,9 +4342,10 @@ class UnassignPresentationLayer(bpy.types.Operator):
     bl_label = "Unassign Presentation Layer"
 
     def execute(self, context):
-        for el in bpy.context.selected_objects:
+        for obj in bpy.context.selected_objects:
-            if el.BIMObjectProperties.presentation_layer.name != "":
+            if not obj.data or not hasattr(obj.data, "BIMMeshProperties"):
-                el.BIMObjectProperties.presentation_layer.name = ""
+                continue
+            obj.data.BIMMeshProperties.presentation_layer_index = -1
         return {"FINISHED"}
 
 

src/ifcblenderexport/blenderbim/bim/prop.py

@@ -1679,8 +1679,6 @@ class BIMObjectProperties(PropertyGroup):
     qto_name: EnumProperty(items=getQtoNames, name="Qto Name")
     has_boundary_condition: BoolProperty(name="Has Boundary Condition")
     boundary_condition: PointerProperty(name="Boundary Condition", type=BoundaryCondition)
-    # TODO: presentation layers should belong to a mesh, not an object
-    presentation_layer: PointerProperty(name="Presentation Layer", type=PresentationLayer)
     structural_member_connection: PointerProperty(name="Structural Member Connection", type=bpy.types.Object)
     representation_contexts: CollectionProperty(name="Representation Contexts", type=Subcontext)
     # Address applies to IfcSite's SiteAddress and IfcBuilding's BuildingAddress
@@ -1729,3 +1727,4 @@ class BIMMeshProperties(PropertyGroup):
     ifc_definition_id: IntProperty(name="IFC Definition ID")
     ifc_parameters: CollectionProperty(name="IFC Parameters", type=IfcParameter)
     active_representation_item_index: IntProperty(name="Active Representation Item Index")
+    presentation_layer_index: IntProperty(name="Presentation Layer Index", default=-1)

src/ifcblenderexport/blenderbim/bim/ui.py

@@ -815,23 +815,25 @@ class BIM_PT_presentation_layer_data(Panel):
         if not context.active_object.data:
             return
         layout = self.layout
-        elem_props = context.active_object.BIMObjectProperties.presentation_layer
+        props = context.active_object.data.BIMMeshProperties
-        props = context.scene.BIMProperties
+        scene_props = context.scene.BIMProperties
 
-        if elem_props.name != "":
+        if props.presentation_layer_index != -1:
-            layout.label(text=f'Object is part of Presentation layer "{elem_props.name}"')
+            layer = scene_props.presentation_layers[props.presentation_layer_index]
+            layout.label(text=f"Assigned to: {layer.name}")
             layout.row().operator("bim.unassign_presentation_layer")
-        else:
+            return
-            if not props.presentation_layers:
-                layout.label(text=f"No presentation layers are available")
-                return
 
-            layout.template_list(
+        if not scene_props.presentation_layers:
-                "BIM_UL_generic", "", props, "presentation_layers", props, "active_presentation_layer_index",
+            layout.label(text=f"No presentation layers are available")
-            )
+            return
-            if props.active_presentation_layer_index < len(props.presentation_layers):
+
-                op = layout.row().operator("bim.assign_presentation_layer")
+        layout.template_list(
-                op.index = props.active_presentation_layer_index
+            "BIM_UL_generic", "", scene_props, "presentation_layers", scene_props, "active_presentation_layer_index",
+        )
+        if scene_props.active_presentation_layer_index < len(scene_props.presentation_layers):
+            op = layout.row().operator("bim.assign_presentation_layer")
+            op.index = scene_props.active_presentation_layer_index
 
 
 class BIM_PT_material(Panel):