Electronic Arts Inc.
SYSTEMS AND METHODS FOR RAY-TRACED SHADOWS OF TRANSPARENT OBJECTS

Abstract:

Rendering shadows of transparent objects using ray tracing in real-time is disclosed. For each pixel in an image, a ray is launched towards the light source. If the ray intersects a transparent object, lighting information (e.g., color, brightness) is accumulated for the pixel. A new ray is launched from the point of intersection, either towards the light source or in a direction based on reflection/refraction from the surface. Ray tracing continues recursively, accumulating lighting information at each transparent object intersection. Ray tracing terminates when a ray intersects an opaque object, indicating a dark shadow. Ray tracing also terminates when a ray exits the scene without intersecting an object, where the accumulated lighting information is used to render a shadow for the pixel location. Soft shadows can be rendered using the disclosed technique by launching a plurality of rays in different directions based on a size of the light source.