Doom 3 light glow

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

hrmm.. i know all about post processing.. nevermind..this Doom3 effect isnt not post processing

well, there are only two (or three) ways of doing it.
1. shader which transforms the vertex position and applys a shiny blur on it
2. post processing as i described
3. rendering the ligth models into a separate buffer and apply the blur there (nearly like 2.)

who tells you its no postprocessing? i had a search for some screenies and i cant tell that its no postprocessing

ok nvermind if figured it out.. this is just some vertex trick with a model.. its nothing fancy, but still looks nice