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ade-the-heat

orange book shaders bump map question

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section 11.8 has the bump map example. In the fragment shader part it has the following: litcolor = surfacecolor*max(dot(normdelta, lightdir), 0.0) where normdelta is the normal and light dir is the light direction. Now, I can't help thinking that the above is wrong, because if the lightdir is directly shining on a point and the normal is directly opposite to the light direction then we have the maximum shininess, but this dot equation will result in a negative value as the two vectors are directly opposite to each other, therefore litcolor will be 0. So have they made a mistake or is it me ? cheers

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Original post by ade-the-heat
section 11.8 has the bump map example.
In the fragment shader part it has the following:

litcolor = surfacecolor*max(dot(normdelta, lightdir), 0.0)

where normdelta is the normal and light dir is the light direction.

Now, I can't help thinking that the above is wrong, because if the lightdir is directly shining on a point and the normal is directly opposite to the light direction then we have the maximum shininess, but this dot equation will result in a negative value as the two vectors are directly opposite to each other, therefore litcolor will be 0.

So have they made a mistake or is it me ?

cheers


email Randy he will email you back. www.3dshaders.com look for a contact link.

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