From 7e3a9e4a75fa88d6c11092a58a79e1c6bdd69398 Mon Sep 17 00:00:00 2001
From: Ryan Schultz <ryan@openingdesign.com>
Date: Wed, 15 Apr 2026 18:11:41 -0500
Subject: [PATCH] Derive materials from selected objects in select_by_material

Previously only the explicit material prop was used. Now all
selected objects' materials are collected, with layer set usages
resolved to the specific layer index matching the clicked material.
Results are joined with " + " in the clipboard query.

Generated with the assistance of an AI coding tool.
---
 .../bonsai/bim/module/material/operator.py    | 94 +++++++++++++++++--
 1 file changed, 86 insertions(+), 8 deletions(-)

diff --git a/src/bonsai/bonsai/bim/module/material/operator.py b/src/bonsai/bonsai/bim/module/material/operator.py
index f4c983928e..0801102fa8 100644
--- a/src/bonsai/bonsai/bim/module/material/operator.py
+++ b/src/bonsai/bonsai/bim/module/material/operator.py
@@ -71,20 +71,98 @@ class SelectByMaterial(bpy.types.Operator):
         return self.execute(context)
 
     def execute(self, context):
-        material = tool.Ifc.get().by_id(self.material)
-        core.select_by_material(tool.Material, tool.Spatial, material=material, should_unhide=self.should_unhide)
+        # Determine the layer index hint from the explicit material prop, if any.
+        # When the user clicks a specific layer in the UI, self.material is that
+        # layer's IfcMaterial. We find its index so we can pull the same layer
+        # from every other selected object's layer set.
+        layer_index = None
+        if self.material:
+            ref_mat = tool.Ifc.get().by_id(self.material)
+            layer_index = self._get_layer_index(ref_mat)
 
-        # copy selection query to clipboard
-        if material.is_a("IfcMaterialLayerSet"):
-            material_name = material.LayerSetName
-        else:
-            material_name = material.Name
-        result = f'material="{material_name}"'
+        materials = {}
+        for obj in context.selected_objects:
+            element = tool.Ifc.get_entity(obj)
+            if not element:
+                continue
+            mat = ifcopenshell.util.element.get_material(element)
+            if not mat:
+                continue
+
+            resolved = self._resolve_material(mat, layer_index)
+            if resolved:
+                materials[resolved.id()] = resolved
+
+        # Fall back to the explicit material prop if selection yields nothing
+        if not materials and self.material:
+            materials = {self.material: tool.Ifc.get().by_id(self.material)}
+
+        if not materials:
+            return {"FINISHED"}
+
+        for mat in materials.values():
+            core.select_by_material(tool.Material, tool.Spatial, material=mat, should_unhide=self.should_unhide)
+
+        result = " + ".join(f'material = "{self._get_name(m)}"' for m in materials.values())
         bpy.context.window_manager.clipboard = result
         self.report({"INFO"}, f"({result}) was copied to the clipboard.")
 
         return {"FINISHED"}
 
+    def _get_layer_index(self, material):
+        """Return the 0-based layer index if material is an IfcMaterial inside a layer set."""
+        if not material.is_a("IfcMaterial"):
+            return None
+        ifc = tool.Ifc.get()
+        for layer in ifc.get_inverse(material):
+            if not layer.is_a("IfcMaterialLayer"):
+                continue
+            for layer_set in ifc.get_inverse(layer):
+                if not layer_set.is_a("IfcMaterialLayerSet"):
+                    continue
+                layers = list(layer_set.MaterialLayers)
+                if layer in layers:
+                    return layers.index(layer)
+        return None
+
+    def _resolve_material(self, mat, layer_index):
+        """Resolve an assigned material to the specific entity to select/name by.
+
+        When layer_index is set, drills into the layer set and returns the
+        IfcMaterial at that index (or None if the set has fewer layers).
+        Otherwise returns the layer set / profile set / constituent set itself.
+        """
+        if mat.is_a("IfcMaterialLayerSetUsage"):
+            mat = mat.ForLayerSet
+        elif mat.is_a("IfcMaterialProfileSetUsage"):
+            mat = mat.ForProfileSet
+
+        if layer_index is not None and mat.is_a("IfcMaterialLayerSet"):
+            layers = list(mat.MaterialLayers)
+            if layer_index < len(layers):
+                return layers[layer_index].Material
+            return None
+
+        return mat
+
+    def _get_name(self, material):
+        if material.is_a("IfcMaterialLayerSet"):
+            if material.LayerSetName:
+                return material.LayerSetName
+            names = [l.Material.Name for l in (material.MaterialLayers or []) if l.Material and l.Material.Name]
+            return ", ".join(names) if names else material.is_a()
+        if material.is_a("IfcMaterialProfileSet"):
+            if material.Name:
+                return material.Name
+            names = [p.Material.Name for p in (material.MaterialProfiles or []) if p.Material and p.Material.Name]
+            return ", ".join(names) if names else material.is_a()
+        if material.is_a("IfcMaterialConstituentSet"):
+            if material.Name:
+                return material.Name
+            names = [c.Material.Name for c in (material.MaterialConstituents or []) if c.Material and c.Material.Name]
+            return ", ".join(names) if names else material.is_a()
+        return getattr(material, "Name", None) or material.is_a()
+
 
 class EnableEditingMaterial(bpy.types.Operator):
     bl_idname = "bim.enable_editing_material"