Creating caustics using projected imagery

The property of a light that allows imagery to be projected from it is called the LightFunction in UDK. In this recipe we'll briefly cover the process to assign it, using an animated example: pool caustics through a FlipBook. Caustics is an effect called by refraction of light through surfaces such as glass and water. Pool caustics is a well known example. Reflective objects can also cast caustics, such as a gold ring's reflection onto a table. In a game you can use a LightFunction to recreate those effects, but you can also use it for any projected imagery, such as the aberration in a torch hotspot, or to fake the effects of stained glass window light splashes (though a way to create stained glass lighting is covered in the chapter following this one). A quick note—pool caustics show on the bottom of the pool (refraction) but they also reflect up onto walls surrounding the pool.

Getting ready

For this example the caustics content is processed through...