been looking at some fixed function normal mapping tutorials, and they all manually calculate a vector from the vertex to the light, to get a tangent space light vector, im wondering if than can be achived with some form of texture matrix? ie. do i dont have to manually update each vertex as im trying to use vertex buffers in my engine and dont want to end up becomming CPU bound.
dont think it can be done via texmatrix cause its individual to each vertex.
if you really want to unload CPU use a VertexProgram, while leaving fixed function there, it is very well supported on most drivers (on old cards it will be emulated by cpu)
You can approximate the light with a direction per-object, then you can use the fixed function. Just put the light direction into the texture environment color. You could even bake (per-object) attennuation into the “length” of that direction vector.