A ray diagram shows how light travels, including what happens when it reaches a surface. In a ray diagram, you draw each ray as: a straight line; with an arrowhead pointing in the direction that ...

To investigate the reflection of light by different types of surface, and the refraction of light by different substances. Remove the block. Join the crosses to show the paths of the light rays ...

but games still aren’t photorealistic in terms of real-world reflections, refractions, and general illumination. To accomplish this, the GPU needs the ability to trace virtual rays of light.