Can I use the geometry shader to create geometry?
Yes, in very limited scenarios. The geometry shader in current D3D10 (2008) parts is not equipped to handle much expansion. This may change in the future. Video card vendors may have a special path for one to four expansions because of existing point-sprite hardware. Any other expansion would have to be very limited. The ParticlesGS and PipesGS samples achieve high frame rates by only doing limited expansion. Only a few points are expanded per frame.
