What is a normal?

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Posts: 608
Joined: 2002.04
Post: #1
Yeah, the subject says my question. What in the world is a normal and what does glNormal do?
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furballphat
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Post: #2
A normal is the vector perpendicular to the face. To see them in action, run the new wave application in the GLUT examples and turn on face normals in the menu.

glNormal sets the normal of every face that is drawn after it, just like glColor.

Normals are used mainly for lighting, but do have other uses.
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #3
OpenGL uses vertex normals rather than face normals. This allows smooth shading, as the normal for a point on a face is interpolated from the normals for the vertices.
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henryj
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Post: #4
To calculate the 'lightness' of a face due to a light shinning on it you need to know which direction the face is pointing. This is the normal.
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Moderator
Posts: 608
Joined: 2002.04
Post: #5
Ah, now I get it! Rolleyes
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