Bump Mapping, how does one implement?

The "bump-map texture" does not hold height values, but normal vectors. It is not a greyscale texture at all, but can be created from a greyscale heightmap.

Bumpmapping is performed in the same way as standard Phong shading is, using the exact same basic lighting equation. The difference is that instead of deriving per-pixel normal vectors as the interpolation between vertex normals, one gets the per-pixel normals from a texture: the normal-map.

One complication is that the light-vector must be transformed into tangent space. To do this one not only needs the face''s normal vector, but also its tangent and binormal vectors.

Here''s one tutorial:

http://www.paulsprojects.net/tutorials/simplebump/simplebump.html

There''s also an old bit of sample code that ATI released years ago:

http://www.ati.com/developer/sdk/RADEONSDK/Html/Samples/OpenGL/RADEONSimpleDOT3.html

I''m not quite sure what this "rotate into texture space" is. It seems like if I use the provided equations on "paul''s projects" site, namely:
r = (x+1)/2;
g = (y+1)/2;
b = (z+1)/2;

and solve them for x,y, and z, I should have them in coordinate space?

quote:

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Original post by RandomAxess
I''m not quite sure what this "rotate into texture space" is. It seems like if I use the provided equations on "paul''s projects" site, namely:
r = (x+1)/2;
g = (y+1)/2;
b = (z+1)/2;

and solve them for x,y, and z, I should have them in coordinate space?

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That equation deals with the fact that a 24 bit RGB texture cannot have negative values. All values must be clamped from 0.0 to 1.0. What that equation does is make the normalized vector entirely positive. 0.5 represents zero; 0.0 represents -1.0; 1.0 represents 1.0.