Anyone notice in Doom 3 the lights have a sort of volumetric glow? What's the procedure for doing this.. I cant figure it out.. is it some kind of depth based trick like the DX SDK example?

ever thought of an (inverse) stencilshadow?? i suggested this to jcl a while ago.
using a volumetric texture (animated) and inner->outer color fade would add the little extra to it.

hmm.. not sure what you mean.. can you explain a little better..?

i mean using the same technique that is used for shadows, but with a visible extrusionshaft and volumetric textures plus color gradient added. there are so many possible parameters using this.

thus you can have the source for the extrusion in center of a lightbulb (for spherical or surrounding glow) and if the source is placed outside (for example a rectangle) you could have a light shaft like for windows

hmm.. maye could work.. i dont know how volumetric texture work tho.. i will look into it. Do you think this is how they do it in the Doom3 example? i cant find anythign out on it..

i dont know doom3 yet, but i think this is a good way to achive various light fx.
you should consider having gobo-textures, parameters for wind-speed, maybe no volumetric texture, but 3d noise fomulas for the cloudy/dusty appearance

what's a gobo texture? I'm afriad i dont really understand what you are talking about.. i just want a simple volumtric glow for now.. just like in Doom3.. i'm sure you can find some screenshots for what i mean..this can be faked using a vertex shader, but's slow and doesnt look smooth.

I think it is a post processing effect.

what's a post processing effect .. the gobo texture or the doom light glow?

you can extract the brightest parts of an image and add a postprocessing filter to it:
original:

brightest parts:

example starglow:

result:


so you would need to render the view into a buffer, use some calculations (multiplication, pow , saturation methods) to it, then blur the result of this (as stars or just gaussian blur) and use this result to brighten the base(rendered view) . as usual this should be the texture of a screen aligned quad.


a gobo is some kind of projection texture, i mentioned this because you where talking about volumetric lights and the gobo-technique adds a lot. but you aren't talking about this as i know now