Normals for GL_TRIANGLE_STRIP

OpenGL OpenGL: Basic Coding
1

Hi,
I am trying to implement lighting in a program. I have written a function which calculates a normal to a polygon given 2 vectors of the polygon. Now the program has a lot of triangles defined using GL_TRIANGLE_STRIP. Will I have to call the normal calculation function for each of the triangle (it is very tedious) or is there an intelligent method to overcome this ?

any ideas…
Milo

2

Unless your surface is defined by some sort of function and you can find it’s tangent at a point I think your out of luck. At least if your surface is static you only have to compute the normals once, but I’m guessing yours is not

3

You will have to compute every normal for every polygon you draw unless if you have pre-computed them and saved them… I dont know what kind of drawing you are doing, but it is generally simple. Normals are independent of how many calls to glBegin( POLY_TYPE ) you make.

Good luck

Miguel Castillo

Originally posted by Milo:
[b]Hi,
I am trying to implement lighting in a program. I have written a function which calculates a normal to a polygon given 2 vectors of the polygon. Now the program has a lot of triangles defined using GL_TRIANGLE_STRIP. Will I have to call the normal calculation function for each of the triangle (it is very tedious) or is there an intelligent method to overcome this ?

any ideas…
Milo [/b]

[This message has been edited by mancha (edited 02-20-2003).]