Reflection Bump Mapping

I have read a few articles about Reflection Bump Mapping, and I’m very impressed. I especially liked the one NVidia did . For the most part I understand it. I’m somewhat distressed though. I’m limited to two textures to do multi-texturing with . I’m curious how to implement reflective bump-mapping because all the articles I’v seen assume you have four or more texture units. Can anyone help, please :>

I know how to do diffuse bump-mapping quite efficiently via dot3 extension. I want to do reflection bump-mapping so I can forget specular bumping altogether (which is just a special case of true reflective bump-mapping anyway). Thanx in advance

You can’t do that on two-unit cards, because it requires more per-pixel power than is available on those cards.

nVidia did post a demo that would do it on a 2-texture card, but it involved reading back the frame buffer and so it is largely impractical for realtime work.

Well, thanx for the replies. Real-time per-pixel reflective bump mapping (say that ten times fast ) on a GeForce 2 would have kicked arse. I thought it wasn’t feasible, but I hoped maybe one of you brilliant persons knew of a way to do it. I really don’t want to do per-vertex reflective mapping, it’s not what I want. I guess I just have to break down and get a better video card. My old GeForce 2 just ain’t cuttin’ it anymore Thanx again!

I think all you need to do is use a multipass technic here… maybe Im missing something.
The bumpmapped torus demo (which I posted a link to here actually) does this.

Coriolis, do you remember the name of the demo you are talking about? Maybe I dont have it.

Nope… just look through the quagmire of demos and you’ll find it eventually. I think it was a source-only demo, with a big disclaimer that it’s only point was to show you could technically do this on a geforce 2, and no statement about practicality.