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normals for polygons

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Hi, a 3d newbie question, i have a polygon (face, 3 vertices), anywhere in the space, and i have a correct normal, now I change the modelview matrix (by glRotate). Do I have to recalc the normal again? I bet I don''t have to, because the normal is affected by the matrix when used (I guess), is that right, any explanations? Thanks

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rotations and translations will not affect the normals. non rigid-body transforms like shear and scale will. You can get openGL to rescale normals with glEnable(GL_NORMALIZE) if you do any scaling.

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