GPU buffers of a system, for custom passes (see the README on extending for MPM).
x sun transmittance (smoke lighting from the grid), y grid heat, z opacity (from the source).
xyz position (local), w age (s).
x temperature (K), y size scale, z random 0…1, w tint (from the source).
xyz velocity (m/s), w life (s; 0 = dead slot).
GPU buffers of a system, for custom passes (see the README on extending for MPM).