i’m looking for an advice about the 3 existing bump mapping techniques: emboss bump mapping, dot3 and environment-mapped bump mapping. i’ve read some articles about this issue, but i have to know which technique i can implement with OpenGL API, i think that is only Emboss Bump Mapping, but maybe i’m wrong?!?!
You can do all three. Emboss bumpmapping can be done on pretty much all cards, Dot3 only on the GeForce and up, and EMBM only the GF3 and up. All Radeons can do Dot3 as well – not sure which ones support EMBM.
There have been various EMBM hacks in all kinds of hardware for some time. You can only get something real with GeForce3+ and Radeon 8500+ cards.
Don’t bother with emboss bump mapping. If you really need to fall back that far, you may as well not bump map. Besides, it looks awful.
Note that the original Radeon actually supports specular+diffuse bump mapping; it can configure its three texture units to do that. GF2 only has two tex units, so it can’t do that. It can do it in two passes, though.