i know the demo your on about; can't find it on that list but know it cause i remember a very excited unamed programmer :: coughdoesn'twannabelintchedcough :: showing me it...
if i remember it actually used a version zbuffering with a raycast,
which effectively the techniqué would be something along the lines of...
-> move camera to where the light is
-> distance the objects (for colouring by distance)
-> move the object in question along the Z axis from the camera pov and check for collision
--> if yes then include said objects in the project
--> if no continue
-> draw the alpha of the object in the projected path directly to the backbuffer
unfortunately the backbuffer in DBP confuses me a bit because without the frontbuffer there is a limited amount of things you can do (as they swap for different tasks)
but you could try the same thing in dbp ... worth a shot, never done it and never seen anyone else really use the backbuffer outside of a DLL
Detonating a nuclear device within the city limits results in a $500 fine!
900mhz|256mb|FX5200Ti 52.16|Dx9|WXP-Pro