Hi, I was hoping you could answer some questions I have on lighting for modern day scenes. When I talk about lighting I mean directional/spotlights 1. How many lights tend to be used in modern day games? 2. How much impact is there when adding an extra light in a scene? 3. Are directional lights less expensive than spotlights? 4. Would 8 lights in a scene kill most graphics cards? 5. Can anyone point me to some websites/papers that talk about using lights in games and the effect of multiple lights? Thanks!

1. Depends on the game really. I don't think you'll see anymore than 3 on a character. For static scenery it will have to be more if you have lots of dynamic lights.

2. If you're doing per-pixel lights, then you may have to to multiple passes over the mesh for each light depending on the hardware you're targetting. For per-vertex, you could get away with up to 8 with 1 pass.

3. Spotlight only affect a few meshes, whilst a directional will affect all the meshes being renderer? But they are cheaper to calculate per vertex/pixel. If you have 8 point/spot lights, then they probably won't all be affecting the same meshes, so you just need to work out which meshes are being affected by which lights.

4. Not if it's per-vertex lighting and a modern-ish gfx card.

Regards, Jim.