Paint

Target: Three.js 0.187.0, three/webgpu and TSL node materials from three/tsl; WebGPU only, no WebGL fallback, no GLSL strings.

Treat paint as a layered surface rather than a single colour.

Layers

Conceptually:

substrate -> primer -> paint -> protective/clear layer -> wear/dirt

Not every object needs every layer explicitly, but the shader should model the important optical consequences.

Controls

Consider:

• base colour
• roughness
• specular
• clearcoat
• clearcoat roughness
• fine surface normal
• colour variation
• fading
• scratches
• edge wear
• dirt

Automotive/train paint

Painted train bodies can use a smooth coloured coating with moderate clearcoat and subtle roughness variation.

Avoid mirror-like paint unless the object is intentionally polished.

Wear

Wear should be spatially meaningful:

• edges
• handles
• door areas
• maintenance access
• exposed lower sections
• high-contact surfaces

Scratches can expose primer or substrate where appropriate.

Dirt

Dirt should accumulate in:

• seams
• recesses
• lower panels
• joints
• underbody areas

Do not apply uniform brown/grey noise.

Signs

Painted signage should retain crisp lettering while allowing the sign substrate to age separately.