feat: Implement weight cutout boundary smoothing for image depth cutout

- Added a new proposal for boundary smoothing in the weight cutout process, differentiating between Split edges and Outline smoothing requirements.
- Introduced a new capability `cutout-boundary-smoothing` to control smoothing strength and default values.
- Updated specifications to define the behavior of boundary-specific smoothing strength and default settings.
- Created tasks to verify the implementation of boundary behavior and asset updates.
- Developed comprehensive tests for depth symmetry and normal scaling to ensure expected behavior and performance.
- Introduced new attributes for normal mapping to facilitate persistent face attributes sharing between depth symmetry and image materials.
- Built a new node group for O Image Depth Symmetry, integrating the new smoothing capabilities and ensuring compatibility with existing workflows.

tools/nodes/groups/image_layer.py

@@ -1,7 +1,9 @@
 """Build O Image Layer."""
 import bpy
 from anyimage.common.material import IMAGE_MATERIAL_NODE_GROUP_NAME
+from anyimage.operators.cutout_tool.shape import NORMAL_REDUCTION_ATTRIBUTE_NAME
 from ..common.shader import build_material_nodes, connect_material_outputs
+from ..common.normal_map import transform_object_normal_color
 
 
 def build_image_layer_group():
@@ -47,18 +49,30 @@ def build_image_layer_group():
         interface.new_socket(name=name, in_out='OUTPUT', socket_type=socket_type)
     nodes, links = group.nodes, group.links
     group_input, group_output, roughness_curve, bump = build_material_nodes(group)
+    normal_attribute = nodes.new('ShaderNodeAttribute')
+    normal_attribute.attribute_type = 'GEOMETRY'
+    normal_attribute.attribute_name = NORMAL_REDUCTION_ATTRIBUTE_NAME
+    normal_weight = nodes.new('ShaderNodeMath')
+    normal_weight.operation = 'SUBTRACT'
+    normal_weight.inputs[0].default_value = 1.0
+    links.new(normal_attribute.outputs['Fac'], normal_weight.inputs[1])
+    weighted_strength = nodes.new('ShaderNodeMath')
+    weighted_strength.operation = 'MULTIPLY'
+    links.new(group_input.outputs['Normal Scale'], weighted_strength.inputs[0])
+    links.new(normal_weight.outputs[0], weighted_strength.inputs[1])
     tangent_normal = nodes.new('ShaderNodeNormalMap')
     tangent_normal.space = 'TANGENT'
-    tangent_normal.location = (-500.0, -100.0)
     object_normal = nodes.new('ShaderNodeNormalMap')
     object_normal.space = 'OBJECT'
-    object_normal.location = (-500.0, -350.0)
     choose_normal = nodes.new('ShaderNodeMix')
     choose_normal.data_type = 'VECTOR'
-    choose_normal.location = (-150.0, -150.0)
-    for normal_map in (tangent_normal, object_normal):
-        links.new(group_input.outputs['Normal'], normal_map.inputs['Color'])
-        links.new(group_input.outputs['Normal Scale'], normal_map.inputs['Strength'])
+    links.new(group_input.outputs['Normal'], tangent_normal.inputs['Color'])
+    links.new(weighted_strength.outputs[0], tangent_normal.inputs['Strength'])
+    normal_color, normal_strength = transform_object_normal_color(
+        group, group_input.outputs['Normal'], weighted_strength.outputs[0],
+    )
+    links.new(normal_color, object_normal.inputs['Color'])
+    links.new(normal_strength, object_normal.inputs['Strength'])
     links.new(group_input.outputs['Object Space'], choose_normal.inputs[0])
     links.new(tangent_normal.outputs['Normal'], choose_normal.inputs[4])
     links.new(object_normal.outputs['Normal'], choose_normal.inputs[5])
@@ -76,14 +90,10 @@ def build_image_layer_group():
     for point in alpha_points:
         point.handle_type = 'AUTO_CLAMPED'
     alpha_curve.mapping.update()
-    group_input.location = (-750.0, 150.0)
-    group_output.location = (350.0, 450.0)
-    alpha_curve.location = (-350.0, 1100.0)
-    roughness_curve.location = (-350.0, 650.0)
     links.new(group_input.outputs['Alpha'], alpha_curve.inputs['Value'])
     links.new(group_input.outputs['Alpha Fix'], alpha_curve.inputs['Factor'])
     processed_alpha = alpha_curve.outputs['Value']
-    connect_material_outputs(group, group_input, group_output, roughness_curve, bump, processed_alpha, (-250.0, 150.0))
+    connect_material_outputs(group, group_input, group_output, roughness_curve, bump, processed_alpha)
     group.color_tag = 'SHADER'
     group.description = f'Prepare {group_name} material outputs.'
     group.use_fake_user = True