[Bf-committers] Bump mapping computation issue
Ton Roosendaal
ton at blender.org
Sun Dec 5 14:21:26 CET 2004
Hi,
Yes, bump mapping now happens in an object's local texture space,
giving the errors as you've illustrated. This is an ancient issue in
Blender.
> It seems to me that the problem comes from perturbated normal
> computation made by blender.
> The formula for normal computation should be:
> perturbated_normal=initial_normal+dI/du*dP/du+dI/dv*dP/dv
> where dI/du and dI/dv are the partial derivates of the texture color
> in texture plane (these are scalars), and where dP/du and dP/dv are
> the partial derivates of the position against texture coordinates
> (vector dP/du "points" in the direction of greater "u").
Euh... I'm not sure about the notation you use here, but such parial
derivates are used in Blender too. I think the only issue lacking is a
proper transformation of the perturbation to global coordinates again,
like the "shi->vn" is expressed in.
I think it's an interesting quality issue for Blender to solve once.
Lemme give it a try now!
Thanks,
-Ton-
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Ton Roosendaal Blender Foundation ton at blender.org
http://www.blender.org
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