Introduction to the DirectX 9 Shader Models - Nvidia

Precision Summary
• If high-precision is fast enough, great
– But remember the low-end DirectX9 cards!
• If you need more speed
– Move constant things to the CPU
• Except when that hurts batching too much
– Move linear things to the vertex shader
– Use texture lookups to replace math
– Use half instead of float
– Reduce shader version
• Some HW runs 1.x faster than 2.0+