Adding Reflections with Ray Tracing

In this chapter, we are going to implement reflections using ray tracing. Before ray tracing hardware was introduced, applications implemented reflections using screen-space techniques. However, this technique has drawbacks as it can only use information from what’s visible on the screen. If one of the rays goes outside the visible geometry on the screen, we usually fall back to an environment map. Because of this limitation, the rendered reflections can be inconsistent, depending on the camera position.

By introducing ray tracing hardware, we can overcome this limitation as we now have access to geometry that is not visible on the screen. The downside is that we might need to perform some expensive lighting computations. If the reflected geometry is outside the screen, this means we don’t have the data from the G-buffer and we need to compute the color, light, and shadow data from scratch.

To lower the cost of this technique...