Re: Raytracing and GL_POINTER_BUFFER_BIT
In fact, this look more such as photon mapping, inverse raytrace or radiosity in my spirit ...
For exemple, increment a value into objects pointed by the GL_POINTER_BUFFER (for each pixel in the screen), can give us the repartition of the energy transmitted from one light to each others object ...
If the object is sphere-mapped or cube-mapped, this can handle a raytracer with two level of recursion (the first intersection and the first reflection)
One pass per light can certainly be a good tradeoff between make really nothing for extend OpenGL and want something that is certainly impossible to make NOW (cf. make realtime raytracing/radiosity/photonmapping with today hardware and a good old standardized API).