Simple Rasterization-Based Liquids
Martin Guay · 2018
This chapter describes the $1 liquid solver for rasterization APIs by combining the simplicity of the particles for dealing with liquids with the simplicity of the grids to compute the forces. Simulating particle-based liquids requires sorting the particles, which is cumbersome when using a rasterization pipeline. The particles are corrected and moved by sampling the grid—which in turn can also be used directly to render the liquid surface by ray casting the splatted density. Splatting is simple to perform in a rasterization pipeline, but can also be costly. Simulating liquids requires dealing with two phases of fluid—the liquid and the air—which can be tricky to model as special care may be required for the interface between the two phases depending on the fluid model. In computer graphics, there are mainly two popular formulations for fluids: strongly incompressible and weakly incompressible. In the grid pass, we update the splatted velocity field with the pressure force, gravity, and artificial pressure for obstacles.