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View Full Version : Reflection Bump Mapping



yoale
04-25-2003, 09:55 AM
I have read a few articles about Reflection Bump Mapping, and I'm very impressed. I especially liked the one NVidia did http://www.opengl.org/discussion_boards/ubb/wink.gif. For the most part I understand it. I'm somewhat distressed though. I'm limited to two textures to do multi-texturing with http://www.opengl.org/discussion_boards/ubb/frown.gif. 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 http://www.opengl.org/discussion_boards/ubb/smile.gif http://www.opengl.org/discussion_boards/ubb/smile.gif

jwatte
04-25-2003, 10:03 AM
You can't do that on two-unit cards, because it requires more per-pixel power than is available on those cards.

Coriolis
04-25-2003, 01:44 PM
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.

yoale
04-28-2003, 02:06 PM
Well, thanx for the replies. Real-time per-pixel reflective bump mapping (say that ten times fast http://www.opengl.org/discussion_boards/ubb/smile.gif) 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 http://www.opengl.org/discussion_boards/ubb/wink.gif Thanx again!

V-man
04-29-2003, 04:57 AM
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.

Coriolis
04-29-2003, 01:51 PM
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.