Advanced Micro Devices, Inc.
Efficient data path for ray triangle intersection

Abstract:

Described herein is a technique for performing ray-triangle intersection without a floating point division unit. A division unit would be useful for a straightforward implementation of a certain type of ray-triangle intersection test that is useful in ray tracing operations. This certain type of ray-triangle intersection test includes a step that transforms the coordinate system into the viewspace of the ray, thereby reducing the problem of intersection to one of 2D triangle rasterization. However, a straightforward implementation of this transformation requires floating point division, as the transformation utilizes a shear operation to set the coordinate system such that the magnitudes of the ray direction on two of the axes are zero. Instead of using the most straightforward implementation of this transform, the technique described herein scales the entire coordinate system by the magnitude of the ray direction in the axis that is the denominator of the shear ratio, removing division.