bump mapping

honkFactory
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Post: #1
Howd,
Does anybody know about bump mapping? I understand the basic basic concept but am not sure how to implement it. If you have any good sources or want to pontificate on this thread I would be happy to hear from you.
A.W.
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honkFactory
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Post: #2
Also what is the difference between texture embossing and bump map embossing? I understand to do none embossing bump mapping you must have a custom renderer to adjust the normals properly. Is there anything like that in ogl.

oops. I think I want to be doing environmental bump mapping and not embossing.
A.W
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #3
Basically, everybody does DOT3 bump-mapping these days. It requires an NVidia GeForce or ATI Radeon class card, though. There is another technique (emboss bump-mapping) which can be done on an ATI Rage 128, but it's a lot more work and not as nice an effect.

Basically how DOT3 bump-mapping works in OpenGL is the red, green and blue components of the "normal map" texture are treated as a normal vector for the surface. The vector to the light is passed in as the per-vertex color, and the dot product of that vector and the bump texture is output (so you get a grayscale image brightest where the light shines directly, and darkest where the light shines obliquely or backwards). That grayscale image is then modulated with the underlying color texture.

You'll find good tutorials online by googling for ARB_texture_env_dot3.
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Moderator
Posts: 699
Joined: 2002.04
Post: #4
Don't know if this will help, NeHe's bump-mapping tutorial.

Mark Bishop
--
Student and freelance OS X & iOS developer
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honkFactory
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Post: #5
I found some dot3 sample code on the apple web site. Unfortunately it is not documented and there is no readme. I'll try to read through it in the morn.

sample code

A.W.
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