What is a normal in OpenGL?

opengl colors light normals
mk. picture mk. · May 6, 2011 · Viewed 21.3k times · Source

I heard that I should use normals instead of colors, because colors are deprecated. (Is that true?) Normals have something to do with the reflection of light, but I can't find a clear and intuitive explanation. What is a normal?

Answer

Thies Heidecke picture Thies Heidecke · May 6, 2011

A normal in general is a unit vector whose direction is perpendicular to a surface at a specific point. Therefore it tells you in which direction a surface is facing. The main use case for normals are lighting calculations, where you have to determine the angle (or practically often its cosine) between the normal at a given surface point and the direction towards a lightsource or a camera.

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