Refactor and enhance geometry node groups for depth plane and material layers

- Updated the depth plane node group to load from an asset and simplified the interface.
- Created a new build script for depth plane geometry nodes.
- Introduced material layer groups for image and depth materials with appropriate sockets.
- Added functionality to connect balloon normal scale to the image material.
- Enhanced tests to validate the new node groups and their connections.
- Ensured that production code does not create node groups directly.

tests/test_mesh_blender.py

@@ -495,6 +495,23 @@ def test_balloon_build_starts_from_the_unified_single_sheet():
     profile = np.empty(len(result.data.vertices), dtype=np.float32)
     profile_attribute.data.foreach_get("value", profile)
     assert profile.min() == 0.0 and profile.max() > 0.0
+    material_tree = result.data.materials[0].node_tree
+    normal_scale_attribute = next(
+        node
+        for node in material_tree.nodes
+        if node.bl_idname == "ShaderNodeAttribute"
+    )
+    assert normal_scale_attribute.attribute_type == "GEOMETRY"
+    assert normal_scale_attribute.attribute_name == shapes.BALLOON_ATTRIBUTE_NAME
+    image_layer = _group_node(material.material_node_group(), material_tree)
+    normal_scale_link = next(
+        link
+        for link in material_tree.links
+        if link.to_node == image_layer
+        and link.to_socket == image_layer.inputs["Normal Scale"]
+    )
+    assert normal_scale_link.from_node == normal_scale_attribute
+    assert normal_scale_link.from_socket == normal_scale_attribute.outputs["Fac"]
     assert result.modifiers[0].node_group.name == shapes.CUTOUT_NODE_GROUP_NAME
     inward = result.matrix_world.to_3x3() @ Vector((1.0, 0.0, 0.0))
     assert np.allclose(tuple(inward), (0.0, 0.0, -1.0), atol=1e-6)
@@ -523,6 +540,10 @@ def test_teddy_preference_writes_the_shared_balloon_attribute():
     profile = np.empty(len(result.data.vertices), dtype=np.float32)
     attribute.data.foreach_get("value", profile)
     assert profile.min() == 0.0 and profile.max() > 0.0
+    assert not any(
+        node.bl_idname == "ShaderNodeAttribute"
+        for node in result.data.materials[0].node_tree.nodes
+    )
 
 
 def test_cutout_material_uses_ior_1_2():
@@ -1228,3 +1249,38 @@ def test_local_cutout_builds_from_blender_image_pixels_without_a_job():
     assert np.allclose(
         copied[:, :, 3], np.flipud(rgba[top:bottom, left:right, 3])
     )
+
+
+def test_balloon_normal_scale_uses_existing_image_layer_input():
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    assert shapes.BALLOON_CUTOUT_SHAPES == frozenset(
+        {"BALLOON", "DEPTH_BALLOON"}
+    )
+    group = bpy.data.node_groups.new(
+        material.IMAGE_MATERIAL_NODE_GROUP_NAME,
+        "ShaderNodeTree",
+    )
+    group.interface.new_socket(
+        name="Normal Scale",
+        in_out="INPUT",
+        socket_type="NodeSocketFloat",
+    )
+    image_material = bpy.data.materials.new("Balloon")
+    image_material.use_nodes = True
+    image_material.node_tree.nodes.clear()
+    image_layer = image_material.node_tree.nodes.new("ShaderNodeGroup")
+    image_layer.node_tree = group
+
+    cutout_object._connect_balloon_normal_scale(image_material)
+
+    assert _inputs(group) == ["Normal Scale"]
+    attribute = next(
+        node
+        for node in image_material.node_tree.nodes
+        if node != image_layer
+    )
+    assert attribute.bl_idname == "ShaderNodeAttribute"
+    assert attribute.attribute_name == shapes.BALLOON_ATTRIBUTE_NAME
+    link = next(iter(image_material.node_tree.links))
+    assert link.from_socket == attribute.outputs["Fac"]
+    assert link.to_socket == image_layer.inputs["Normal Scale"]

tests/test_node_assets.py

@@ -0,0 +1,32 @@
+import unittest
+from pathlib import Path
+
+
+PROJECT_ROOT = Path(__file__).resolve().parents[1]
+SOURCE_ROOT = PROJECT_ROOT / "src" / "anyimage"
+
+
+class NodeAssetTest(unittest.TestCase):
+    def test_production_code_does_not_create_node_groups(self):
+        offenders = []
+        for path in SOURCE_ROOT.rglob("*.py"):
+            if "bpy.data.node_groups.new" in path.read_text(encoding="utf-8"):
+                offenders.append(path.relative_to(PROJECT_ROOT).as_posix())
+        self.assertEqual(offenders, [])
+
+    def test_runtime_node_group_entries_load_assets(self):
+        material_source = (
+            SOURCE_ROOT / "operators" / "common" / "mesh_result.py"
+        ).read_text(encoding="utf-8")
+        plane_source = (
+            SOURCE_ROOT / "operators" / "convert_to_plane" / "nodes.py"
+        ).read_text(encoding="utf-8")
+        self.assertIn("return load_asset_node_group(group_name)", material_source)
+        self.assertIn(
+            "return load_asset_node_group(DEPTH_PLANE_NODE_GROUP_NAME)",
+            plane_source,
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()