From: Angus Dorbie (dorbie++at++sgi.com)
Date: 06/12/2000 14:20:39
The bump mapping itself is pretty well documented in my opinion, but I'm
biased :-). The procedural code to generate the logo has some
appropriate comments but was never really the objective of the exercise
and isn't documented. It is pretty complex code.
Ignore my procedural code and strike out on your own, the only missing
part for geometry which isn't procedurally generated is the production
of tangent vectors and binormal vectors based on available geoset
information rather than implicit surface functions.
The tangent vector should be computed using the three dimensional
texture derivative for the s texture coordinate and the binormal should
either be the cross product of this and the surface normal or it should
be the 3D derivative for the t coordinate.
You will want to average these vectors for gouraud shaded contiguously
texture mapped adjacent triangles, just as you average surface normals
for gouraud shaded lit objects.
Cheers,Angus.
Sakns wrote:
>
> Hi there,
>
> Angus has written a couple of bumpammaping demos applying bumpmaps
> to known/constructed geometry where coords/colos/norms/tex_coords
> are calculated on the fly by the application.
> I am trying to generalize the procedure to any pfb file where some
> of the above might not be specified. But I need to understand
> better the code and having problems since it is undocumented. Is
> there a more detailed explanation somewhere?
> Has anybody else done the same thing?
>
> Thank you.
>
> =====
> Athanasios Gaitatzes (Saki)
> e-mail: gaitat++at++yahoo.com
> url: http://www.i.am/gaitatzes
>
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