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Calculating normals...

Started by elis-cool Dec 23, 2002 at 2:41 AM 2 replies 300+ views

Original Post

Dec 23, 2002 at 2:41 AM

Ok, I understand what normals are etc, but im just not sure on how to calculate them or what their actual values are... Basicly I want to know what would the vertex normals be for a qaud with vertices at [x,y,z]: [0,0,0] [0,20,0] [20,0,0] [20,20,0] ? would they all be 1.0,1.0,1.0 or something??

iodine23

Dec 23, 2002 at 12:37 PM

0,0,1 or 0,0,-1. The normal is perpendicular to the surface. Your surface is in the xy plane so its normal will be in the z-axis. You should be able to figure that out logically.

Mathematically, the normal of two vectors is the cross product of those two vectors. In your case, you can use the vectors [0,20,0] and [20,0,0] for one of the corners. The cross product yields [0,0,400] or [0,0,-400] depending on the order of the vectors.

If you normalize the vectors to [0,1,0] and [1,0,0] the cross product becomes [0,0,1] or [0,0,-1] depending on the order of the vectors... there''s your normal.

elis-cool

Dec 23, 2002 at 6:40 PM

normalize means what?

Gladiator

Dec 23, 2002 at 6:46 PM

Normalizing a vector is the process of scaling a vector''s length to 1. In order to do that, you have to divide each of the vector''s components (x, y, z) by the current length of the vector.

Normalizing is the process. A normalized vector is called a Normal.

If you calculate the length/magnitude of a normal you will end up with 1.

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