Optimize Cutout Geometry Nodes

- Refactor Depth Cutout to reuse the projected outline field, reducing redundant boundary calculations and improving performance.
- Derive the center field from shared low-frequency fields, eliminating an unnecessary blur operation.
- Implement triangle-only strip cleanup for Depth Cutout, as the input is confirmed to be triangulated.
- Short-circuit zero-thickness branches in both Cutout and Depth Cutout to avoid unnecessary geometry generation.
- Standardize internal attribute naming with a new `_o_` prefix and implement wildcard cleanup for temporary attributes.
- Update relevant tests to ensure functionality remains consistent and validate changes against existing behavior.

tests/tools/nodes/test_depth_cutout.py

@@ -1,9 +1,10 @@
 """Contracts for smooth depth volume, editable presets and normal masks."""
+from collections import Counter
 import bpy
 import numpy as np
 import pytest
 
-from tools.nodes.groups.image_depth_cutout import build_volume_fields
+from tools.nodes.groups.image_depth_cutout import build_image_depth_cutout_group, build_volume_fields
 from anyimage.common.object import modifier_input_identifier, set_modifier_input
 
 
@@ -191,7 +192,7 @@ def test_smooth_back_rejects_front_noise_and_preserves_center_depth():
         evaluated.to_mesh_clear()
 
 
-def test_depth_cutout_normal_map_only_affects_front_faces():
+def test_depth_cutout_normal_reduction_uses_point_domain():
     from tests.support.depth_surface import surface
     obj, set_value = surface()
     set_value("Thickness", 0.3)
@@ -200,14 +201,77 @@ def test_depth_cutout_normal_map_only_affects_front_faces():
     mesh = evaluated.to_mesh()
     try:
         attribute = mesh.attributes["o_normal_reduction"]
-        assert attribute.domain == "FACE"
-        weights = [1.0 - item.value for item in attribute.data]
-        assert weights.count(1) == len(obj.data.polygons)
-        assert weights.count(0) == len(mesh.polygons) - len(obj.data.polygons)
+        assert attribute.domain == "POINT"
+        values = [item.value for item in attribute.data]
+        assert values
+        assert set(values) <= {0.0, 0.5, 1.0}
+        assert 0.0 in values and 1.0 in values
     finally:
         evaluated.to_mesh_clear()
 
 
+def test_depth_cutout_reuses_boundary_and_slow_field_nodes():
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    group = build_image_depth_cutout_group()
+    counts = Counter(node.bl_idname for node in group.nodes)
+    assert counts["GeometryNodeInputMeshEdgeNeighbors"] <= 15
+    assert counts["GeometryNodeBlurAttribute"] <= 12
+
+
+def test_center_derives_from_shared_slow_fields():
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    points = [(x, y) for y in range(3) for x in range(3)]
+    mesh = bpy.data.meshes.new("Center fields")
+    mesh.from_pydata(
+        [(x, y, 0) for x, y in points], [],
+        [(0, 1, 4, 3), (1, 2, 5, 4), (3, 4, 7, 6), (4, 5, 8, 7)],
+    )
+    profile = mesh.attributes.new("o_balloon", "FLOAT", "POINT")
+    for value in profile.data:
+        value.value = 0.2
+    obj = bpy.data.objects.new("Center fields", mesh)
+    bpy.context.collection.objects.link(obj)
+    group = bpy.data.node_groups.new("Center derivation test", "GeometryNodeTree")
+    group.interface.new_socket(name="Geometry", in_out="INPUT", socket_type="NodeSocketGeometry")
+    group.interface.new_socket(name="Thickness", in_out="INPUT", socket_type="NodeSocketFloat").default_value = 1
+    group.interface.new_socket(name="Geometry", in_out="OUTPUT", socket_type="NodeSocketGeometry")
+    source = group.nodes.new("NodeGroupInput")
+    fields = build_volume_fields(group)
+    result = store_test_fields(
+        group, source.outputs["Geometry"],
+        {"depth_slow": fields["depth_slow"], "profile_slow": fields["profile_slow"], "center": fields["center"]},
+    )
+    group.links.new(result, group.nodes.new("NodeGroupOutput").inputs["Geometry"])
+    obj.modifiers.new("Fields", "NODES").node_group = group
+    bpy.context.view_layer.update()
+    evaluated = obj.evaluated_get(bpy.context.evaluated_depsgraph_get())
+    result = evaluated.to_mesh()
+    try:
+        depth_slow = np.array([item.value for item in result.attributes["depth_slow"].data])
+        profile_slow = np.array([item.value for item in result.attributes["profile_slow"].data])
+        center = np.array([item.value for item in result.attributes["center"].data])
+        np.testing.assert_allclose(center, depth_slow - profile_slow, atol=1e-5)
+    finally:
+        evaluated.to_mesh_clear()
+
+
+def test_zero_thickness_short_circuits_shell_without_warnings():
+    from tests.support.depth_surface import surface, evaluated
+    obj, set_value = surface()
+    set_value("Thickness", 0.0)
+    points, faces = evaluated(obj)
+    assert len(faces) == len(obj.data.polygons)
+    modifier = obj.modifiers[0]
+    result = obj.evaluated_get(bpy.context.evaluated_depsgraph_get())
+    mesh = result.to_mesh()
+    try:
+        assert not list(modifier.node_warnings), [
+            warning.message for warning in modifier.node_warnings
+        ]
+    finally:
+        result.to_mesh_clear()
+
+
 @pytest.mark.parametrize("thickness,inflation", [
     (0.0, 1.0), (0.02, 0.0), (0.02, 0.0001),
     (0.02, 0.5), (0.1, 0.5), (0.1, 1.0),