   Time of day lighting ?
  Okay, from observing the way that the game Brütal Legend looks thanks to it's time of day lighting, I've suddenly taken interest in skylights/atmospheric lighting/etc. With this in mind, my goals for pursuing such a system are as follows: More visually interesting background than a static skybox, ambient lighting that integrates objects/characters into the environment, providing specular and other reflections.Okay, so let me see if I have the basic idea: You do the simulation that generates the look of the sky (takes a few frames to update). This gets rendered to a cube map so that it can be displayed as a skybox, and/or for reflections. Then blur and filter the cube map, so it can be converted to SH constants for indirect lighting. Does that sound about right? Am I missing anything?So the real question now is, finding an approach that fits my needs. Please note, I'm not looking for a physically accurate model. I'm just looking for one that is artist-friendly, moderately tweakable, and fast. I want to be able to pull off skies that don't exist in the real world, including peculiar gradients between any kind of color. Camera altitude may change, but shouldn't ever leave the atmosphere. Needs distinct night and day. Finally, needs to be HDR safe.So, can anyone suggest techniques and or links that can show me how to set up such a system?   