Ok, but you have to know that each light which produces bumps uses at the very least one texture unit. If you have a textured object and you want to apply bumpmapping with one light, then you need at least 2 texture units (1 unit for the ''decal'' texture of the object and 1 unit for bumpmapping)... not really a problem. But if you have 2 lights for this textured object, you will need at least 3 texture units (1 unit for decal, 2 units because 2 lights produce 2 different bumps) ... not really a problem for GeForce3+ or Radeon7000+ cards, but definately a problem for GeForce2- cards ! And in that case it is still possible but it means multipass.

There are a few solutions though.

First solution : render as many bumps as you can in one pass, and no more. If the user owns a GeForce3 (4 texture units) then he will have up to 4 bumps simultaneously but no more. If the user owns a GeForce2 (2 texture units) then he will have up to 2 bumps but no more.

Second solution : render all bumps even if it means multipass. Users that have a low number of texture units will have a significant framerate drop, but no quality is lost.

Third solution : render only the "most important" bumpmap. For each object, you have to rate the "light importance" of each light and you only render bumpmapping with the light that gets the best score with this object.