Download here: DubLight.zip
Dub lights are a quick, cheap method of faking global illumination in multipass rendering. They also handle simple color gradients.
To use in a scene: Add the "Dub Light Base.mdl," "Dub Light.lit" and "Dub Light.act" files to your project. Drag a Dub Light Base into your choreography, and drop the Dub Light action onto it. Add as many dub lights as you want, just remember to decrease the intensity of Dub Light.lit as you do so -- 100% works fine for two, 50% for four, probably 25% for eight (experiment to taste).
To render: Turn on Multi-Pass and Motion Blur. I've been using 16 passes (4x4 oversampling) and 100% motion blur. Probably any amount of motion blur would work just as well.
To change the colors: The "Front Color" and "Back Color" groups control the color of the light based on which direction it's facing. Notice that in wireframe mode the Dub Light Base model looks like an arrow. The head of the arrow is the front color, and the tail is the back color. In the pic above, the front color is set to pink, and the back is lime green.
The guts: Dub lights use a couple of simple expressions and constraints to spin a light randomly in a dome around your scene. Since the light positions are random, you'd probably get some weird flickering if you tried to use them in an animation -- a pseudorandom function that would repeat every frame might work better than the Rand() function for animation. If you do anything cool like that with them, let me know.
What's next: Yves Poissant has information and a great collection of real skylights at his site. Dub lights are no substitute for a good skylight rig. My hope is to get usable results by taking advantage of the time difference between anti-aliasing passes -- the old spinning light rig trick.
(Sorry for pasting the readme file in here. I didn't feel like retyping any of that.)
Basically, that's more text than this idea deserves. It's a one-light, expression-based random skylight. The nice thing about it is you can add as many to a scene as you want. Shadows not good enough? Drop a couple more in. (Just remember to drop the intensity of the .lit file as you go.) They also handle linear color gradients.
Also, the above pic took just shy of 15 minutes to render on a single 1.8 G5, with a few other things running.
Now back to what I was SUPPOSED to be working on. Cheers, all.
