Watertight ray triangle intersection that does not restore with double precision

摘要

Described in this application is a technique for performing a ray triangular intersection test in a manner that produces a watertight result. This technique involves transforming the coordinates of the triangle so that the origin is at the origin of the ray. The technique involves projecting a coordinate system into the ray''s view space. Then the technique calculates the centroid coordinates and interpolates the centroid coordinates to get the intersection time. The sign of the center of gravity coordinate indicates whether or not a hit occurs. The above calculations are performed in non-directional floating point rounding mode to provide watertightness. The non-directional rounding mode is a mode in which the mantissa of a rounded number is rounded in such a way that it does not depend on the sign of the number.