Shadow Volume Rendering

[dalangalma]

I've read a couple articles about Shadow Volume rendering, and I just want to be sure - to render shadow volumes requires 2.5 passes per light, correct? That is, 2 passes of rendering the scene (light on, light off) and 2 passes of rendering shadow volumes (back and front faces). You can't do better than that? It seems like that would be awfully slow...

[crystall]

Originally posted by dalangalma:
I've read a couple articles about Shadow Volume rendering, and I just want to be sure - to render shadow volumes requires 2.5 passes per light, correct? That is, 2 passes of rendering the scene (light on, light off) and 2 passes of rendering shadow volumes (back and front faces). You can't do better than that? It seems like that would be awfully slow...On hardware supporting the EXT_stencil_two_side and EXT_stencil_wrap extensions you can merge the back/front passes into one.

I've read a couple articles about Shadow Volume rendering, and I just want to be sure - to render shadow volumes requires 2.5 passes per light, correct?it depends on the technique being used. there are techniques for shadowing open geometries that require 3 passes, inspite of the two sided stencil test extension, due to the fact that it requires 3 different vertex programs to operate.

check out the advanced forum. there's a recent topic regarding spot-lights that might be helpful as an overview of techniques.