A PARALLEL RAYCAST ALGORITHM OF CSG MODELS ON CM2

One of the main problems for CSG models manipulators is the fast visualization of the results. The high computational cost on single-processor architectures makes the CSG scheme useless for the interactive creation of the model.This article deals with a parallel algorithm based on general purpose SIMD architecture, such as the Connection Machine 2, for the visualization of high quality shaded images of CSG models in nearly real time.The technique is based on a pixels parallelization of the Ray Casting algorithm. The Frame Buffer is divided into severals regions and for each of them we determine the CSG reduced model projected on it. Then a processor is assigned to each pixel in the sub-area; it determines the equation of the ray crossing the pixel and, using the Ray Casting technique, the nearest intersection point to the pixel on which it calculates the illumination model.