   Rendering GPU particles?
  Here's my little problem... Writing particle data in to textures is no problem, but how do I get the data rendered on to the screen where all the particles should be? Obviously it's impracticle to loop through the particle textures for each pixel to see if it collides with a particle.   
  When you draw your vertex buffer of particles, you sample the position map in the vertex shader using vertex texture fetch to get the position for the particle.   