To get the cheap enviroment mapping effect, I can do:
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
-same of T
Now how are these S and T values calculated?
Anyone know the algorithm?
Where to find info on it?
Is there a way to extract those automatically generated values?
>>Now how are these S and T values calculated?
>>Anyone know the algorithm?
>>Where to find info on it?
OpenGL 1.2.1 specs chapter 2.10 “Coordinate Transformations” page 37.
Download here: http://www.opengl.org/developers/documentation/OpenGL12.html
A good description of spheremapping and other techneques is given in the file GDC2K_ShadingComputations.pdf that can be found under http://www.nvidia.com/Marketing/Developer/DevRel.nsf/bookmark/486693A161C04F3D882568A500827B15