...Requirements: XNA 3.1, Visual Studio 2008 (for source code), a graphics card that supports Shader Model 3.0 .
This simulates a field of particles. Physics calculations are done using HLSL with the vertex texture fetch. Each particle's velocity is stored in a pixel's rgb values in a texture. The position is stored in a separate texture. The velocity texture is run through an HLSL shader to update the velocities, and then the same sort of thing occurs for the position texture. This allows these calculations to be done on the GPU rather than CPU. ...