Generate wood patterns with temperature changes

Script to generate texture via temperature gradients to get horizontal stripes that "look like wood". The last and only updated source code is now on github at https://github.com/MoonCactus/gcode_postprocessors/tree/master/wood

This is the code of my post here: http://betterprinter.blogspot.fr/2012/10/shades-of-brown-with-wood-filament-via.html

The owl is Cushwa's popular design at http://www.thingiverse.com/thing:18218

The picture which highlights the effect on a regular polygonal