Hey folks,

I've been up and down the internet looking for clues and I've had no luck so here goes...

I'm trying to implement Volumetric Light Scattering and I've run into a few snags.

The basic process (unless I misunderstand) is as follows:

1. Render the background with all the foreground geometry rendered black.
2. Perform image processing to create crepuscular rays.
3. Blend the processed image with a "regular" render and voila, godrays.

Conceptually I get it, that's not a problem; I'm just not getting the implementation details for step one. I have a fair amount of programming experience but shaders seem a little alien to me as I'm new to them.

Can/should I get the black geometry image before I stick it into the shader? Can/should I implement this as a multi-pass shader?

Any help, as always, would be greatly appreciated.

Cheers, Ryan