Apple Shake 4 - Manual (Page 987)

Chapter 32 The Cookbook 987
Rain Macro
This macro can be used to generate rain to throw into a background. The rain is divided
into three sheets, fg, mid, and bg. The lighting controls affect the height of the sheets.
By using a low value, you can get a fake feeling of depth. Sort of.
Ramp2D Macro
This uses the NGLRender drawing routines to draw a polygon on the screen to give you
a ramp between any two points. The wedgeSize parameter should be brought down if
you start to see artifacts along the edges.