Ivanyangyangxi Artclaw Bridge Artclaw Material

ArtClaw Material — 材质节点图操作接口

Official ArtClaw skill providing atomic tools for Material node graph manipulation. All tools are registered via @ue_tool and exposed through MCP.

Architecture

AI (OpenClaw) ──MCP──▶ Skill Hub ──▶ material_node_ops.py (this skill)
                                  ──▶ material_ops.py (existing: instance params, actor materials)
                                  ──▶ get_material_nodes (existing: read node graph)

This skill handles: node graph write operations (create, delete, connect, edit nodes). Existing tools handle: reading node graphs (get_material_nodes), material instance parameters (get_material_parameters, create_material_instance), actor material assignment (get_actor_materials, set_actor_material).

Tools Summary

✅ 核心工作流：先写伪代码，再创建节点

📋 通用节点图工作流（伪代码→映射→分组创建→验证→布局）见 dcc-node-graph-workflow skill。 本 skill 专注 UE 材质的 API 细节、节点类名和属性速查。

UE 材质图是纯数据流节点图，伪代码示例：

# 伪代码
base_color = tex_diffuse * tint_color
roughness  = lerp(0.2, 0.9, tex_roughness.r)
metallic   = param_metallic

# 节点映射
TextureSampleParameter2D  → tex_diffuse / tex_roughness
Constant3Vector           → tint_color
Multiply                  → base_color = tex * tint
ComponentMask(R)          → .r channel
Lerp                      → roughness
ScalarParameter           → metallic

Standard Workflow

1. Create material → create_material(asset_name, package_path)
2. Set material properties → set_material_properties(material_path, {blend_mode, shading_model, ...})
3. Add nodes → create_material_expression(material_path, expression_class, pos_x, pos_y) (repeat)
4. Set node properties → set_expression_property(material_path, node_name, property_name, value)
5. Wire nodes together → connect_material_expressions(from_node, from_output, to_node, to_input)
6. Wire to material outputs → connect_material_property(from_node, from_output, "BaseColor")
7. Compile + verify → recompile_material(material_path, save=true)

Existing tools for read/query:

• get_material_nodes(material_path) — full BFS traversal with connections
• list_material_expressions(material_path) — quick flat list
• get_material_parameters(material_path) — instance parameter values

Expression Class Names

Pass full class name (e.g. MaterialExpressionConstant3Vector) or short name (e.g. Constant3Vector) — the tool auto-prefixes.

Common types:

Constants: Constant, Constant2Vector, Constant3Vector, Constant4Vector Parameters: ScalarParameter, VectorParameter, StaticSwitchParameter Textures: TextureSample, TextureSampleParameter2D, TextureCoordinate Math: Add, Subtract, Multiply, Divide, Power, Lerp, Clamp, OneMinus, Saturate Utility: ComponentMask, AppendVector, Fresnel, Noise, Time, Panner Custom: Custom (HLSL code), MaterialFunctionCall, Comment

Full list: references/node_types.md

Pin Names

When connecting nodes, use pin names:

• Default/first pin: empty string ""
• TextureSample outputs: "" (RGBA), RGB, R, G, B, A
• Math node inputs: A, B
• Lerp inputs: A, B, Alpha
• Power inputs: Base, Exponent
• Clamp inputs: Input, Min, Max

Property Setting

Use set_expression_property for node-specific properties:

• Constant: r (float)
• Constant3/4Vector: constant ({r, g, b, a})
• Parameter nodes: parameter_name (str), default_value, group (str)
• TextureSample: texture (asset path string)
• TextureCoordinate: coordinate_index (int), u_tiling (float), v_tiling (float)
• Custom: code (HLSL string), description (str)
• Panner: speed_x (float), speed_y (float)

Material Properties

Use set_material_properties for top-level material settings:

• blend_mode: Opaque | Translucent | Masked | Additive | Modulate
• shading_model: DefaultLit | Unlit | Subsurface | SubsurfaceProfile | ClearCoat
• two_sided: bool
• opacity_mask_clip_value: float (for Masked mode)

Details: references/material_properties.md

Example: Create Simple PBR Metal Material

1. create_material(asset_name="M_BlueMetal", package_path="/Game/Materials")
2. create_material_expression(material_path="/Game/Materials/M_BlueMetal", expression_class="Constant3Vector", pos_x=-300, pos_y=0)
   → returns node_name e.g. "MaterialExpressionConstant3Vector_0"
3. set_expression_property(..., node_name="MaterialExpressionConstant3Vector_0", property_name="constant", property_value={"r":0.1,"g":0.2,"b":0.8})
4. connect_material_property(..., from_node="MaterialExpressionConstant3Vector_0", from_output="", material_property="BaseColor")
5. create_material_expression(..., expression_class="Constant", pos_x=-300, pos_y=150)
   → "MaterialExpressionConstant_0"
6. set_expression_property(..., node_name="MaterialExpressionConstant_0", property_name="r", property_value=1.0)
7. connect_material_property(..., from_node="MaterialExpressionConstant_0", from_output="", material_property="Metallic")
8. create_material_expression(..., expression_class="Constant", pos_x=-300, pos_y=250)
   → "MaterialExpressionConstant_1"
9. set_expression_property(..., node_name="MaterialExpressionConstant_1", property_name="r", property_value=0.3)
10. connect_material_property(..., from_node="MaterialExpressionConstant_1", from_output="", material_property="Roughness")
11. recompile_material(material_path="/Game/Materials/M_BlueMetal", save=true)

Error Handling

All tools return {"success": true/false, ...}. On failure, error field contains a human-readable message. Common errors:

• Material not found — invalid path
• Asset is MaterialInstanceConstant, not a Material — use instance tools instead
• Unknown expression class — check references/node_types.md
• Connection failed — pin name mismatch or type incompatibility
• Node not found — wrong node_name (use list_material_expressions to verify)

Compile Validation

recompile_material automatically validates compilation results via shader instruction counts:

• compile_success: true — num_pixel_shader_instructions > 0
• compile_success: false — returns error hint + 0 instructions
• Only saves on success — prevents saving broken materials

Response includes stats with instruction/sampler/texture counts for debugging.

Common compile failures:

• Custom node HLSL: undefined variables (must be passed as inputs, not assumed)
• Type mismatch: connecting float3 to float1 input
• Missing connections: material property expects input but none connected

Deployment

Copy scripts/material_node_ops.py to the ArtClaw Skills directory:

{UEPlugin}/Content/Python/Skills/material_node_ops.py

Or place in 00_official/artclaw-material/ as a manifest-based skill. Skill Hub auto-discovers @ue_tool decorated functions on file save.

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