Fog function 2- lua stock

Update - using the circle generator from ZardOz's fantastic fog of war, I've streamlined my code a bit and smoothed the fog transition!
See ZardOz's level here: http://principiagame.com/level/6126

Blocks out an area except a circle in the middle, as in my Abyss cinematic.

Colours, layers and size definable on the fly by adjusting the function's arguments.

*NOTE: uses pixels 1 through 32 (x,y) on the texture.*

Call using "fog(x,y,z,size,r,g,b)"