Your web site in very interresting (Congratulation !)
I have some problem with (Normals computing).
I already have a vectorial algebra course (School - Mathematic) and I well understand the way of calculating the normal vectors of one facet.
But my problem is knowing which facets do I choose among all those available when I built an object ?
Suppose I want to draw a sphere like this one: http://astronomy.swin.edu.au/pbourke/opengl/sphere/
AND calculating normals facets MANUALLY…
Is it better to compute each coords of sphere inside an array and use it after to compute the normal or I could compute it in same time.
I don’t understand, cause to compute a normals facets, I need 3 vectors but in this exemple there are only 2 vectors at each glBegin(…) / glEnd.
How can I create the third vector ?
After picking the 3 vector, If understand well I have to do this :
Subtract 2 vector from the 3 vector by a matrix soustraction operation.
Do the Cross product of the result
Normalize the lenght of the result vector.
Could you help me just a little bit cause I don’t find any docs on internet.
The docs I found, just related the way to compute normal but not USE it.
PS : Thank to help me and excuse me to disturb you.