Intel do CPU-based ray-tracing in Quake Wars

"The game itself was vastly expanded when compared to original title. Intel’s Daniel Pohl showed how the engine now shoots three million rays in all directions, enabling collision detection based on rays alone.

Also, during the conversion, some effects were integrated by default, even if they had not been planned. One of those effects was fog shadow on the floor and physically-correct refractions of water.

If you ever dived into a swimming pool or sea and looked up, you could have seen that the world is distorted. Now, ET: Quake Wars has the very same effect.

An impressive part of demonstration was looking at glass surfaces. Glass now reflects the environment to the tiniest detail - no LOD trickery here."

Intel converts ET: Quake Wars to ray-tracing