- Split MeshPainter into partial classes (Setup/Backend/Gpu/Cpu) for maintainability
- Add ambient occlusion painting, packed with metallic/smoothness into one
MSO mask map (R=metallic, G=occlusion, A=smoothness) bound to both
_MetallicGlossMap and _OcclusionMap, kept independently paintable via
per-channel ColorMask
- Gate painting from a single IsChannelActive source so AO-only strokes work
- Blend albedo/emission in linear space on CPU to match the GPU framebuffer
- Pre-compensate data-channel writes for sRGB->linear so GPU matches CPU
- Harden GPU shader fallback to reflect real backend state
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Extend the painter from a single albedo map to three paint maps:
albedo (_BaseMap), packed metallic+smoothness (_MetallicGlossMap,
R=metallic A=smoothness), and emission (_EmissionMap/_EmissionColor).
- Per-channel toggles (paint albedo / metallic+smoothness / emission)
- Metallic/Smoothness sliders and emission color + intensity brush params
- One brush shader drives all maps; metallic-smoothness uses a work
layout (R=metallic G=smoothness A=coverage) and a pack pass
(Hidden/MeshPaintPackMS) to the URP layout after each stroke
- GPU and CPU backends mirror all three maps with the same mask and
seam-dilation logic
- Material keywords (_METALLICSPECGLOSSMAP, _EMISSION) enabled and the
new maps seeded from the original material values