Quick Normal Question

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1 comment, last by THACO 18 years, 9 months ago
Ok, this should be simple but just want to double check. I am exporting info from 3dsmax. I have to multiply each vertex by the offset matrix to move it into world space. I assume I have to also mult the Normals by the same matrix because while translation wouldn't change the normal, any rotation to the overall object would. Also does this mean I have to normalize the normals again because multiplication of a point3 and a matrix might make it longer than a unit vector? -THACO
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You should multiply the normals by the transformation, without the translation component. You can do this by setting (assuming D3D-style matrix orientation) matrix components 41,42 and 43 to zero, or by casting to a 3x3 matrix by some method (eg in HLSL).
-Scoot
I am just curious as to why? Im actually using the 3dsmax sdk, which includes built in types for a matrix and point3. It actually contains a method to zero out the translation so that is a plus for me. Thanks. Also should I make sure there is no Scale component also?

-THACO

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