So yes, I have a room loaded with radiation and glowing green lights, which are to be "drained" away, but I don't want to simply disable all the lights and rad markers because the room would just *snap* to clean suddenly when the player hits the switch. So is there a way to fade out the lights, as slowly as possibly, to give the effect of the air becoming purified?

It'd be even better if I could get the rad markers to fade too, giving less and less radiation to the player until gone, but that's not as important.

Suggestions?

Well I think the only way to do the lights would be to make your own animated light object that fades. But for the radiation, simply do this. Make a new explosion, it deals 0 dmg and has 0 force, and no nif. So the player never see's it, hears it or feels it. Then set the radiation radius to the same as your rad marker, and same intensity. Then when they hit the switch, disable the radiation marker, and spawn the explosion in the middle of the room. That way the ammount will remain the same, then the invisible explosion is making it, and that kind fades away after the time you set. That should work to what you want. But the lights will be much more difficult to do.

I have to say, that I think the radiation fade would be rather quick with that method. You could also write a script the disables the rad markers and enables progressively weaker ones over time. I don't know if radiation is cumulative, but you could try to place several rad markers and then just disable them one-at-a-time over a time period as well. You could do the same thing with the lights unless you know how to animate them - which you just might.

EDIT: I Just looked up an explaosion and there is a setting for the disipation time on the radiation, so Gunmaster's suggestion is actually a really good one. Forget what I said.

Jumping in to say I've done the fading lights via the disable method and it's not that difficult. The trick is to stack a bunch of weaker lights on top of each other so that when they're all on, together they equal the desired light level for the areas 'on' setting (they're cumulative). Then using a script, you disable one of them, run a very short counter timer, then disable another, run timer again, etc.. until all are off. The end result is the lights (depending on how many you use and how large the steps are between them) appear to fade to nothing over time. The only issue is using too many local lights, which brings out a renderer limitation where only some will show, so animating one is still always the best option for a super smooth fade.

Hmmmm yes that idea would work, but I would worry that it would hit performance un-necessarily hard. Fo3 already has enough penalty for having too-many lights in a space, I think stacking them would force the engine to treat them all as different, independent lights and you would get a multiple-performance hit. I wouldn't recommend this method unless your in a smaller space where you could get away with lots of lighting and not much loss to performance. I'm working with alot of big, open spaces right now and am having to cut down on the lights to get the performance back.

Food for thought..

You can get a, 'fade off' effect to the light using the FX Glow objects. You can get it to 'fade out' if you child it to an object that is then disabled.
If you do not have the 'Pop In' check box marked, then it will slowly fade away, imitating the light turning off.

Yes they're all treated as independant lights, so definately don't go nutz with it. When I used it, it was in a small hallway between areas, but was careful to make sure the total local light count for the entire cell wasn't much more than a default Beth cell interior.

The radiation "explosion" works well, but I'm having trouble with the lights. I *am* working with a large room, so I can't use the light stacking method unfortunately. Far too many lights.

Is there a way to change an object's emittance setting through script? Perhaps there's a way to get it to dim out from there, since the effect I'm going for is a fade from green to white (the air purifying thing).

If all you want is to change the color from green to white, you may want to try an image space modifier (IMOD). This can slowly fade the color from one to another over the whole cell. It won't do anything for diming a specific light though.