GeForce 6800 GT 4xAA/8xAF SM3.0

GeForce 6800 GT 4xAA/8xAF SM2.0

X800 XT 4xAA/8xAF

FiringSquad: Which aspects of shader model 3.0 are you taking advantage of?

Cevat Yerli: We're using looping and branching mainly. We're using the floating point FP16 FP 32 of course. But mainly we're using the aspect of making sure that more lighting can be accomplished with flow control and branching so we can encode for example 4 lights in one pass, which is speeding up the rendering. Our utilization of 3.0 shader model is essentially tied to performance improvements. So for example we can render, previously with 2.0 we were rendering one light per pass and now we're rendering up to four lights per pass.

Second aspect is that we're using geometry instancing which is a big performance gainer, mostly for outdoors but also for indoors. On the outdoors we're using for example to reduce the draw calls from trees, grass, and other vegetation objects, we're using the same or similar object meshes in different positions and orientations. They're rendered in one draw call with different attributes in the vertex shader. That reduces the draw calls.