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Normals for a 4 vertex polygon?

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Hiya I''ve been looking for info on creating normals for a polygon, I''ve found routines that take 3 vertices and calculate a normal for the shape, but my polygons have 4 vertices. How do I create a normal for a 4 vertex shape please? All 4 vertices will be in random xyz positions each time Thanks a lot for any ideas Adam

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The way i see it. use three for one and three for the other one.
Since 4 vertices might not lay on a plane, but 3 will always create a plane.

i suggest using the vertices beside the one you need a normal for

[edited by - bgcjr on December 2, 2002 10:47:56 PM]

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Depends whether your poly is supposed to be representing a flat or curved surface. Eg. If the poly is the side of a cube, the normals on each 4 vertices will always be pointing in the same direction. If it is a section of a sphere, they will all be pointing in different directions. So it really depends on the object you are trying to represent, not the poly itself.

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