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Vivanco

Scaling 3DS Models -- probs with normals

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Hey all, I have been having problems with my 3DS models in my game engine. The models look fine and the lighting works great, normals all calculated correctly i think. I can move the models around using glTranslatef() but if I try to make them larger using glScalef() they look crappy. Does scaling the models affect the normals, thus making the lighting look crap??? Is there another way to change the size of the models without affecting the normals??? Any help would be great. Cheers (o)..A Bee bit my bottom, now my bottom Big..(o)

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what happens is the normals get sclaed too, and usually end up with a length greater or less than one, what you need to do is
re-normalize the normals in the GL driver, using GL_NORMALIZE

but what i sugest you do is manually scale the verticies and leave
the normals alone (normals are not to be affected by scaling operations)

for each vertex in vertexpool
vertex.xyz * scale
next

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Vertex normals need to be transformed using the inverse transpose of the matrix that was used to transform the associated points. If you don't know what this means, look into matrix mathematics.

EDIT: Nevermind. You're doing a uniform scale. You need to re-normalize the vectors, or not scale them at all, as already mentioned.



[edited by - Nemesis2k2 on September 28, 2003 4:38:46 AM]

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