I'm not sure if it is intended or a bug, but could you make it so photons won't change temperature (and thus color) of filter? It's hard to make filter go into specific color without this (e.g. when making lasers filters will change color under heavy rain of photons till they'll be red, it's unwanted).

Hm... It only seems to happen with ambient heat enabled. It should be changed, so it won't change it's temperature, just like other heat-powered materials (wifi, etc.)

NICE!