\ / First of all, I wish everybody a Merry X-mas / \ Ok.. Now back to my problem. How do I calculate Normals?? I''m not sure.

OK, although this is covered *many* times across the internet (try googling):

The normal to a triangle or some other polygon can be calculated by taking the cross product of two adjacent edges.

Say the triangle is represented by three (3D) points Pi.

Edge 1 can be E1 = P2 - P1
Edge 2 can be E2 = P3 - P1

Now normal N is

N = E1 X E2

Where X is the cross product, defined like this in a function:




Now if you want normals for a smooth mesh (ie normal per vertex), you need to accumulate the normals for each triangle for each vertex and then average them together (and renormalize if necessary).

[edited by - JuNC on December 26, 2002 3:14:34 PM]