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.

tools/nodes/groups/image_cutout.py

@@ -2,7 +2,7 @@
 import bpy
 from anyimage.operators.cutout_tool.shape import NORMAL_REDUCTION_ATTRIBUTE_NAME
 from ..common.nodes import interface_socket, group_input, math_node, float_input, menu_switch, read_float_attribute, store_float_attribute, prepare_node_group
-from ..common.cutout import _extrude_layers, _offset_geometry_y, _remove_zero_thickness, _set_layer_y, _shade_output
+from ..common.cutout import _extrude_layers, _offset_geometry_y, _set_layer_y, _shade_output
 
 
 NODE_GROUP_NAME = "O Image Cutout"
@@ -108,6 +108,13 @@ def _set_segmented_layer_y(
 def _build_shell(group, geometry, thickness):
     nodes = group.nodes
     links = group.links
+    zero = math_node(nodes, "LESS_THAN")
+    zero.inputs[1].default_value = 1e-6
+    links.new(thickness, zero.inputs[0])
+    choose = nodes.new("GeometryNodeSwitch")
+    choose.input_type = "GEOMETRY"
+    links.new(zero.outputs[0], choose.inputs["Switch"])
+    links.new(geometry, choose.inputs["True"])
     front = math_node(nodes, "MULTIPLY")
     front.inputs[1].default_value = 0.0
     links.new(thickness, front.inputs[0])
@@ -121,12 +128,20 @@ def _build_shell(group, geometry, thickness):
         back.outputs[0],
         thickness,
     )
-    return _remove_zero_thickness(group, geometry, shaped, thickness)
+    links.new(shaped, choose.inputs["False"])
+    return choose.outputs[0]
 
 
 def _build_balloon(group, geometry, thickness):
     nodes = group.nodes
     links = group.links
+    zero = math_node(nodes, "LESS_THAN")
+    zero.inputs[1].default_value = 1e-6
+    links.new(thickness, zero.inputs[0])
+    choose = nodes.new("GeometryNodeSwitch")
+    choose.input_type = "GEOMETRY"
+    links.new(zero.outputs[0], choose.inputs["Switch"])
+    links.new(geometry, choose.inputs["True"])
     profile = read_float_attribute(group, 'o_balloon')
     front_scale = math_node(nodes, "MULTIPLY")
     links.new(profile, front_scale.inputs[0])
@@ -142,7 +157,8 @@ def _build_balloon(group, geometry, thickness):
         negative_front.outputs[0],
         front_scale.outputs[0],
     )
-    return _remove_zero_thickness(group, geometry, shaped, thickness)
+    links.new(shaped, choose.inputs["False"])
+    return choose.outputs[0]
 
 
 def build_image_cutout_group():