I am trying to integrate bump mapping and have problems with the specular highlights/half vector. I guess it is not really complicated but I just don’t get it.
The objects in the scene are positioned with glRotate and glTranslate (an object is a display lists, centered around 0/0/0), and the light source is a directional light, not a point light (but I could use a far-away point light as well, if that helps).
I got the light vector in world space, and dp3’d with the tbn matrix, the diffuse lighting works. So I guess, I need the half vector in world space as well, and then multiply this with the tbn matrix and so on.
My problem is that I do not have the vertex coordinates in world space… and after the modelview transformation, they are not in world space as well, I guess, due to the fact that the gluLookAt-call also affects the MVP.
So what to do? I somehow need the viewer/vertex and verte/light vectors in the same coordinate space to compute the half vector, but I have no idea of how to achieve this.
Thansk and regards,