Semi-Langrangian Grid Fluid Solver

[andewx]

Implement fluid.Grid as a solver class and verify fluid grid solution capabilities. Fluid model is exported in voxelized construct form with mesh lines points and internalized mesh cubes visualized as transluscent pressure gradient representations.

For mesh/air surface representation we can represent a parametric polynomial function f(x,y) = z and reconstruct the function using the partial derivatives of sampled fluid air interfaces. This function is used to construct the fluid surface via as a triangle strip.