Phase 3 of the surface fluid simulation:
- Bingham yield stress in the CPU solver and integrate kernel: effective
viscosity grows as local shear rate drops, so mud piles up and freezes
instead of spreading like water.
- FluidSurfaceRenderer: screen-space fluid rendering pipeline (splat depth+
thickness with atomic min/add, bilateral depth smoothing, view-space normal
reconstruction from depth gradients, water/mud shading), mirrored 1:1 in
FluidSsfKernels.h and driven through the gpgpu compute queue with a CPU
fallback and PPM debug output.
- Script API: Fluids.newSurfaceRenderer + FluidSurface (render/setCamera/
setMode/writePpm).
- Design + usage spec under docs/dev/specs.
- Tests: yield-stress freeze, SSF single-particle depth/normal/thickness,
water-vs-mud shading, GPU SSF pipeline with PPM artifact (17 fluids cases).