vassvik

Realtime Fluid Simulation: Projection

The core of most real-time fluid simulators, like the one in EmberGen, are based on the "Stable Fluids" algorithm by Jos Stam, which to my knowledge was first presented at SIGGRAPH '99. This is a post about one part of this algorithm that's often underestimated: Projection

MG4_F32.mp4

Stable Fluids

The Stable Fluids algorithm solves a subset of the famous "Navier Stokes equations", which describe how fluids interact and move. In particular, it typically solves what's called the "incompressible Euler equations", where viscous forces are often ignored.

DonKarlssonSan

// Hyperboloc functions by toneburst from 
// https://machinesdontcare.wordpress.com/2008/03/10/glsl-cosh-sinh-tanh/
// These are missing in GLSL 1.10 and 1.20, uncomment if you need them 

/*
/// COSH Function (Hyperbolic Cosine)
float cosh(float val)
{
    float tmp = exp(val);
    float cosH = (tmp + 1.0 / tmp) / 2.0;