I think all of the glsl examples of fragment lighting I've seen use a fixed point light source.
I need a fragment shader does performs lighting with a variably positioned light.
My understanding of lighting calculations requires me to calculate the vector between the fragment position and light position.
the problem is gl_FragCoord is in screen space while the lightSource[i] is in object space.
anyone have any hints/pointers/code that can peform fragment lighting with a moving light?