IfcOpenShell · falken10vdl · Apr 9, 2026 · Apr 15, 2026 · Apr 16, 2026
diff --git a/src/bonsai/bonsai/bim/handler.py b/src/bonsai/bonsai/bim/handler.py
@@ -335,9 +335,10 @@ def get_user(ifc: ifcopenshell.file) -> Union[ifcopenshell.entity_instance, None
 
 
 def viewport_shading_changed_callback(area: bpy.types.Area) -> None:
-    shading = area.spaces.active.shading.type
-    if shading == "RENDERED":
-        tool.Style.get_style_props().active_style_type = "External"
+    shading_type = area.spaces.active.shading.type
+    tool.Style.restore_material_style_types(shading_type)
+    if shading_type == "SOLID":
+        area.spaces.active.shading.color_type = "MATERIAL"
 
 
 def subscribe_to_viewport_shading_changes():

diff --git a/src/bonsai/bonsai/bim/import_ifc.py b/src/bonsai/bonsai/bim/import_ifc.py
@@ -133,10 +133,6 @@ def load_texture_maps(self, shape_has_openings: bool) -> None:
                 if shape_has_openings and coords.is_a("IfcIndexedTextureMap"):
                     continue
                 tool.Loader.load_indexed_map(coords, self.mesh)
-            elif tool.Style.get_texture_style(material):
-                # No explicit coordinate mapping (e.g. IFC2X3 has no IsMappedBy,
-                # and IFC4 COORD uses generated UVs). Bake XY→UV as fallback.
-                tool.Loader.load_generated_uv_map(self.mesh)
 
     def assign_material_slots_to_faces(self) -> None:
         if not self.mesh["ios_materials"]:

diff --git a/src/bonsai/bonsai/bim/module/project/operator.py b/src/bonsai/bonsai/bim/module/project/operator.py
@@ -1239,6 +1239,10 @@ def execute(self, context):
         tool.Project.set_default_modeling_dimensions()
         tool.Root.reload_grid_decorator()
         bonsai.bim.handler.refresh_ui_data()
+        for screen in bpy.data.screens:
+            for area in screen.areas:
+                if area.type == "VIEW_3D":
+                    bonsai.bim.handler.viewport_shading_changed_callback(area)
         return {"FINISHED"}
 
     def get_decomposition_elements(self) -> set[ifcopenshell.entity_instance]:

diff --git a/src/bonsai/bonsai/bim/module/style/__init__.py b/src/bonsai/bonsai/bim/module/style/__init__.py
@@ -45,7 +45,9 @@
     operator.SelectByStyle,
     operator.SelectStyleInStylesUI,
     operator.SetAssetMaterialToExternalStyle,
+    operator.SuggestShadeFromExternalStyle,
     operator.UnlinkStyle,
+    operator.TogglePreferIfcShading,
     operator.UpdateCurrentStyle,
     operator.UpdateStyleColours,
     operator.UpdateStyleTextures,

diff --git a/src/bonsai/bonsai/bim/module/style/operator.py b/src/bonsai/bonsai/bim/module/style/operator.py
@@ -503,6 +503,165 @@ def set_prop_group(prop_group):
             set_prop(prop_name)
 
 
+class TogglePreferIfcShading(bpy.types.Operator):
+    bl_idname = "bim.toggle_prefer_ifc_shading"
+    bl_label = "Toggle Fast/Pretty"
+    bl_description = (
+        "Toggle between Fast (IFC-native shading) and Pretty (external .blend style) for ALL styles.\n\n"
+        "SHIFT+CLICK to apply to this style only"
+    )
+    bl_options = {"REGISTER", "UNDO"}
+    material_name: bpy.props.StringProperty(name="Material Name", default="", options={"SKIP_SAVE"})
+    single_only: bpy.props.BoolProperty(name="Single Only", default=False, options={"SKIP_SAVE"})
+
+    def invoke(self, context, event):
+        if event.shift:
+            self.single_only = True
+        return self.execute(context)
+
+    def execute(self, context):
+        wm = context.window_manager
+        space = tool.Blender.get_view3d_space()
+        is_solid = space and space.shading.type == "SOLID"
+
+        if is_solid:
+            if space.shading.color_type == "TEXTURE":
+                space.shading.color_type = "MATERIAL"
+            else:
+                meshes_needing_uv = []
+                for obj in bpy.context.scene.objects:
+                    if not isinstance(obj.data, bpy.types.Mesh):
+                        continue
+                    for slot in obj.material_slots:
+                        mat = slot.material
+                        if not mat or not tool.Blender.get_ifc_definition_id(mat):
+                            continue
+                        style_elements = tool.Style.get_style_elements(mat)
+                        if style_elements.get("IfcSurfaceStyleWithTextures") and not obj.data.uv_layers:
+                            meshes_needing_uv.append(obj.data)
+                            break
+                wm.progress_begin(0, max(len(meshes_needing_uv), 1))
+                try:
+                    for i, mesh in enumerate(meshes_needing_uv):
+                        tool.Loader.load_generated_uv_map(mesh)
+                        wm.progress_update(i)
+                finally:
+                    wm.progress_end()
+                space.shading.color_type = "TEXTURE"
+            return {"FINISHED"}
+
+        if self.single_only:
+            mat = bpy.data.materials.get(self.material_name)
+            if not mat:
+                return {"CANCELLED"}
+            msprops = tool.Style.get_material_style_props(mat)
+            msprops.prefer_ifc_shading = not msprops.prefer_ifc_shading
+        else:
+            # Default: apply to all IFC materials
+            source_mat = bpy.data.materials.get(self.material_name)
+            new_value = not source_mat.BIMStyleProperties.prefer_ifc_shading if source_mat else True
+            ifc_mats = [m for m in bpy.data.materials if tool.Blender.get_ifc_definition_id(m)]
+            wm.progress_begin(0, max(len(ifc_mats), 1))
+            try:
+                for i, mat in enumerate(ifc_mats):
+                    tool.Style.get_material_style_props(mat).prefer_ifc_shading = new_value
+                    wm.progress_update(i)
+            finally:
+                wm.progress_end()
+        return {"FINISHED"}
+
+
+class SuggestShadeFromExternalStyle(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.suggest_shade_from_external_style"
+    bl_label = "Suggest Shade from External Style"
+    bl_description = (
+        "Generate a Shade style (Surface Colour + Transparency) from the external .blend style.\n\n"
+        "ALT+CLICK to apply to all styles with an external .blend style"
+    )
+    bl_options = {"REGISTER", "UNDO"}
+    material_name: bpy.props.StringProperty(name="Material Name", default="", options={"SKIP_SAVE"})
+    all_styles: bpy.props.BoolProperty(name="All Styles", default=False, options={"SKIP_SAVE"})
+
+    def invoke(self, context, event):
+        if event.alt:
+            self.all_styles = True
+        return self.execute(context)
+
+    def _execute(self, context):
+        if self.all_styles:
+            candidates = [
+                (mat, tool.Style.get_style_elements(mat))
+                for mat in bpy.data.materials
+                if tool.Blender.get_ifc_definition_id(mat)
+            ]
+            candidates = [(mat, se) for mat, se in candidates if tool.Style.has_blender_external_style(se)]
+            wm = context.window_manager
+            wm.progress_begin(0, max(len(candidates), 1))
+            count = 0
+            try:
+                for i, (mat, style_elements) in enumerate(candidates):
+                    wm.progress_update(i)
+                    if self._apply_to_material(mat, style_elements):
+                        count += 1
+            finally:
+                wm.progress_end()
+            self.report({"INFO"}, f"Shade style generated for {count} style(s).")
+        else:
+            mat = bpy.data.materials.get(self.material_name)
+            if not mat:
+                return {"CANCELLED"}
+            style_elements = tool.Style.get_style_elements(mat)
+            if not tool.Style.has_blender_external_style(style_elements):
+                self.report({"ERROR"}, "No external .blend style assigned. Please assign an external style first.")
+                return {"CANCELLED"}
+            self._apply_to_material(mat, style_elements)
+        props = tool.Style.get_style_props()
+        if props.is_editing:
+            core.load_styles(tool.Style, style_type=props.style_type)
+
+    def _apply_to_material(self, material: bpy.types.Material, style_elements: dict) -> bool:
+        external_style = style_elements["IfcExternallyDefinedSurfaceStyle"]
+        style_path = Path(tool.Ifc.resolve_uri(external_style.Location))
+        data_block_type, data_block = external_style.Identification.split("/")
+
+        try:
+            db = tool.Blender.append_data_block(str(style_path), data_block_type, data_block)
+        except OSError as e:
+            self.report({"WARNING"}, f'Could not open blend file for "{material.name}": {e}')
+            return False
+        if not db["data_block"]:
+            self.report({"WARNING"}, f'Could not load external style for "{material.name}": {db["msg"]}')
+            return False
+
+        ext_mat = db["data_block"]
+        surface_colour, transparency = tool.Style.get_representative_material_color(ext_mat)
+        bpy.data.materials.remove(ext_mat)
+
+        ifc_style = tool.Ifc.get_entity(material)
+        attributes: dict = {
+            "SurfaceColour": {
+                "Name": None,
+                "Red": surface_colour[0],
+                "Green": surface_colour[1],
+                "Blue": surface_colour[2],
+            },
+        }
+        if tool.Ifc.get_schema() != "IFC2X3":
+            attributes["Transparency"] = transparency
+
+        shading_style = style_elements.get("IfcSurfaceStyleShading")
+        if shading_style:
+            tool.Ifc.run("style.edit_surface_style", style=shading_style, attributes=attributes)
+        else:
+            tool.Ifc.run(
+                "style.add_surface_style",
+                style=ifc_style,
+                ifc_class="IfcSurfaceStyleShading",
+                attributes=attributes,
+            )
+        return True
+
+
 class DisableEditingStyles(bpy.types.Operator):
     bl_idname = "bim.disable_editing_styles"
     bl_options = {"REGISTER", "UNDO"}

diff --git a/src/bonsai/bonsai/bim/module/style/prop.py b/src/bonsai/bonsai/bim/module/style/prop.py
@@ -118,6 +118,19 @@ def update_shader_graph(self: Union["Texture", "BIMStylesProperties"], context:
     tool.Loader.create_surface_style_with_textures(material, shading_data, textures_data)
 
 
+def _make_clear_null_updater(null_prop: str):
+    def _update(self: "BIMStylesProperties", context: bpy.types.Context) -> None:
+        self[null_prop] = False
+        update_shader_graph(self, context)
+
+    return _update
+
+
+update_diffuse_colour = _make_clear_null_updater("is_diffuse_colour_null")
+update_specular_colour = _make_clear_null_updater("is_specular_colour_null")
+update_specular_highlight_value = _make_clear_null_updater("is_specular_highlight_null")
+
+
 UV_MODES = [
     ("UV", "UV", _("Actual UV data presented on the geometry")),
     ("Generated", "Generated", _("Automatically-generated UV from the vertex positions of the mesh")),
@@ -221,24 +234,29 @@ class BIMStylesProperties(PropertyGroup):
     transparency: bpy.props.FloatProperty(
         name="Transparency", default=0.0, min=0.0, max=1.0, update=update_shader_graph
     )
-    # TODO: do something on null?
-    is_diffuse_colour_null: BoolProperty(name="Is Null")
+    is_diffuse_colour_null: BoolProperty(name="Is Null", update=update_shader_graph)
     diffuse_colour_class: EnumProperty(
         items=[(x, x, "") for x in get_args(ColourClass)],
         name="Diffuse Colour Class",
-        update=update_shader_graph,
+        update=update_diffuse_colour,
     )
     diffuse_colour: bpy.props.FloatVectorProperty(
-        name="Diffuse Colour", subtype="COLOR", default=(1, 1, 1), min=0.0, max=1.0, size=3, update=update_shader_graph
+        name="Diffuse Colour",
+        subtype="COLOR",
+        default=(1, 1, 1),
+        min=0.0,
+        max=1.0,
+        size=3,
+        update=update_diffuse_colour,
     )
     diffuse_colour_ratio: bpy.props.FloatProperty(
-        name="Diffuse Ratio", default=0.0, min=0.0, max=1.0, update=update_shader_graph
+        name="Diffuse Ratio", default=0.0, min=0.0, max=1.0, update=update_diffuse_colour
     )
-    is_specular_colour_null: BoolProperty(name="Is Null")
+    is_specular_colour_null: BoolProperty(name="Is Null", update=update_shader_graph)
     specular_colour_class: EnumProperty(
         items=[(x, x, "") for x in get_args(ColourClass)],
         name="Specular Colour Class",
-        update=update_shader_graph,
+        update=update_specular_colour,
         default="IfcNormalisedRatioMeasure",
     )
     specular_colour: bpy.props.FloatVectorProperty(
@@ -248,24 +266,24 @@ class BIMStylesProperties(PropertyGroup):
         min=0.0,
         max=1.0,
         size=3,
-        update=update_shader_graph,
+        update=update_specular_colour,
     )
     specular_colour_ratio: bpy.props.FloatProperty(
         name="Specular Ratio",
         description="Used as Metallic value in PHYSICAL Reflectance Method",
         default=0.0,
         min=0.0,
         max=1.0,
-        update=update_shader_graph,
+        update=update_specular_colour,
     )
-    is_specular_highlight_null: BoolProperty(name="Is Null")
+    is_specular_highlight_null: BoolProperty(name="Is Null", update=update_shader_graph)
     specular_highlight: bpy.props.FloatProperty(
         name="Specular Highlight",
         description="Used as Roughness value in PHYSICAL Reflectance Method",
         default=0.0,
         min=0.0,
         max=1.0,
-        update=update_shader_graph,
+        update=update_specular_highlight_value,
     )
     reflectance_method: EnumProperty(
         name="Reflectance Method",
@@ -347,6 +365,22 @@ def update_shading_style(self: "BIMStyleProperties", context: bpy.types.Context)
         tool.Style.switch_shading(blender_material, self.active_style_type)
 
 
+def update_prefer_ifc_shading(self: "BIMStyleProperties", context: bpy.types.Context) -> None:
+    blender_material = self.id_data
+    style_elements = tool.Style.get_style_elements(blender_material)
+    has_external = tool.Style.has_blender_external_style(style_elements)
+    if self.prefer_ifc_shading:
+        self.active_style_type = "Shading"
+        tool.Style.switch_shading(blender_material, "Shading")
+    elif has_external:
+        self.active_style_type = "External"
+        tool.Style.switch_shading(blender_material, "External")
+    else:
+        self.active_style_type = "Shading"
+        tool.Style.switch_shading(blender_material, "Shading")
+    blender_material.update_tag()
+
+
 class BIMStyleProperties(PropertyGroup):
     ifc_definition_id: IntProperty(name="IFC Definition ID")
     active_style_type: EnumProperty(
@@ -356,9 +390,19 @@ class BIMStyleProperties(PropertyGroup):
         default="Shading",
         update=update_shading_style,
     )
+    prefer_ifc_shading: BoolProperty(
+        name="Fast / Pretty",
+        description=(
+            "Toggle between Fast (IFC-native shading) and Pretty (external .blend style). "
+            "When set to Fast, viewport switches to Material Preview or Rendered will not activate the external style."
+        ),
+        default=True,
+        update=update_prefer_ifc_shading,
+    )
     is_renaming: BoolProperty(description="Used to prevent triggering handler callback.", default=False)
 
     if TYPE_CHECKING:
         ifc_definition_id: int
         active_style_type: tool.Style.StyleType
+        prefer_ifc_shading: bool
         is_renaming: bool