Douglas S. Lima douglaslimadev1

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.

	// ref: http://www.codercorner.com/RadixSortRevisited.htm
	// http://stereopsis.com/radix.html
	// int/float: https://github.com/lshamis/FloatRadixSort
	// string: https://github.com/rantala/string-sorting/blob/master/src/msd_ce.cpp

	struct str {
	const char *str;
	const char *end;
	int len;
	};

	/*============================================================================


	NVIDIA FXAA 3.11 by TIMOTHY LOTTES


	------------------------------------------------------------------------------
	COPYRIGHT (C) 2010, 2011 NVIDIA CORPORATION. ALL RIGHTS RESERVED.
	------------------------------------------------------------------------------
	TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THIS SOFTWARE IS PROVIDED

	#include <windows.h>

	extern "C"
	{
	#pragma section(".CRT$XIA",long,read)
	#pragma section(".CRT$XIZ",long,read)
	#pragma section(".CRT$XCA",long,read)
	#pragma section(".CRT$XCZ",long,read)
	#pragma section(".CRT$XPA",long,read)
	#pragma section(".CRT$XPZ",long,read)

	extern "C"
	{
	int _fltused;

	#ifdef _M_IX86 // following functions are needed only for 32-bit architecture

	__declspec(naked) void _ftol2()
	{
	__asm
	{