Apple Shake 4 - Manual (Page 967)

Chapter 32 The Cookbook 967
Filtering Tips
This section illustrates creative uses of Shake’s filtering nodes.
Volumetric Lighting
This script can be found in doc/html/cook/scripts/volumetric.shk. This simple hack gives
you fake volumetric lighting by using Filter–RBlur. One of the key principles is that RBlur
is dog-slow, so it is better, if you can, to apply a radial blur on a low-resolution element
and then scale it up. To get the volume effect, subtract one RBlur from another. You
should also drop your quality down (to .25, for example) when testing.
In this tree, RBlur3 is generating the main cone of light. Move2D1 is used to scale it up,
saving you a little rendering time. CornerPin2 is used to generate the “shadow” element
and place it on the ground in perspective. RBlur1 is at full resolution to maintain the
crispness of the rays.