The Ray Tracer Challenge

Fresnel Effect

The Fresnel effect (that’s a silent “s,” by the way—thank the French for that) is the name for how light behaves on transparent surfaces. If you’ve ever stood beside a lake, you’ll be familiar with it. Looking straight down into the water, you see the rocks and fish below the surface. But as you look up toward the far shore, the water becomes more opaque and reflects more and more of the scenery. The following figure demonstrates this, with a brown/green checkered plane for the bottom of the lake, and a second, transparent plane as the water. A white/gray checkered wall in the far distance stands in for the scenery.

Notice specifically ...