Crystal Space supports full realtime modification of anything. Of course it means that you can't use lightmapping so you have three options:
- Don't use lighting: just paint everything fullbright. This is the easiest and fastest option but you'll get no lighting at all.
- Use software dynamic lighting. This works on all hardware but it doesn't look very nice.
- Use hardware dynamic lighting. Performance and quality of this depends a bit on hardware but you can make things look very nice indeed if you use shaders like parallax or others.