# OpenGL DirectX version of gl_NormalMatrix

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I was wondering if anyone knows what the equivalent DirectX code is for the OpenGL function gl_NormalMatrix()? Thanks.

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What does gl_NormalMatrix do? Is it only used in GLSL? I can't find a reasonable explanation through Google.

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Well, that's basically what I'm asking. :)

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Yes gl_NormalMatrix() is for GLSL.

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Quote:
 Original post by Evil SteveWhat does gl_NormalMatrix do?

gl_NormalMatrix is the upper-left 3x3 part of the ModelViewProjection matrix (i.e. the rotational-component of the model-space to view-space transform). So multiplying a normal by gl_NormalMatrix transforms the normal into screen space.

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What are the other parts to be set to? 0 or 1?

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Quote:
 Original post by EnochDagorWhat are the other parts to be set to? 0 or 1?

It is a 3x3 matrix, so there are no other parts. If you want to do the same with a 4x4 matrix (which is more expensive to multiply), I believe you can do it by setting the remaining row and column to match the identity matrix:

N N N 0
N N N 0
N N N 0
0 0 0 1

Edit: actually, I am not all that sure about this, it would be great if someone could confirm.

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Ah, I see. In that case there's no D3D equivalent. This thread is relevant I think.

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