Felt Tips looking at a simple employment of toComp(), fromComp() and fromCompToSurface() to make a lens flare follow a 3D light and then project a circle onto a 3D layer that also follows the light. This is a good example of what After Effects is doing with layer space, world space and comp space where you are able to have a layer’s effect interact with other layers by using fromCompToSurface() to transfer space values.

from Felt Tips: “14 minute After Effects expressions tutorial, showing you how to use toComp(), fromComp() and fromCompToSurface() to make a lens flare follow a 3D light and then project a circle onto a 3D layer that also follows the light. Also, some stuff to help you get an intuitive grasp of the various After Effects spaces: layer space, world space and comp space. Second of a series of ten tutorials showing some very cool and very useful expressions that are only a few lines long.”