ZDoom

Okay nevermind then, that idea was nixed.

[quote=Nash post_id=1247166 time=1699269176 user_id=267]
Just stack multiple black 3D floors with increasing opacity. :mrgreen:

vOLumETriC liGhtINg
[/quote]

Well in a way I'm already doing that. I've a bunch of "ExtraFloor_LightOnly" things that gradually light up more and more the higher it goes since it's technically cheaper while the main sector itself has 0 brightness.

Hastig, how would this be done? Right now, there is no way to do this except with sticking a glowing flat on a floor/ceiling but that's not doable with 3D floors.

I'm already doing that.

But then I came up with a [url=https://github.com/ZDoom/gzdoom/issues/2247]much better idea...[/url]

Just stack multiple black 3D floors with increasing opacity. :mrgreen:

vOLumETriC liGhtINg

What you really want here is not a glow but a gradient of the light level.

I tend to agree with all the previous posts that subtractive glows are not a good idea.

[quote="Graf Zahl" post_id=1193849 time=1625386102 user_id=75]
And yet another specialty effect with no realistic use cases would be added.
Sorry, I'm done with this. There's already so much baggage in the engine I'd rather get rid of that I won't consider adding more of this.
[/quote]

Coming back to this, I need this for deep chasms to appear endless and to fade out the walls. [url=https://puu.sh/JTQuG/1772eecb31.png]An example would be these pits.[/url] Trying to develop a gradient that only goes up a third of the way has proven to be unbelievably difficult that requires the use of "Transfer Brightness" specials that add needless tedium and complexity when a simple subtractive glow would work.

Using negatives lights it is then.

And yet another specialty effect with no realistic use cases would be added.
Sorry, I'm done with this. There's already so much baggage in the engine I'd rather get rid of that I won't consider adding more of this.

It'll look bad, just as subtractive lights already do. Light simply does not "subtract", period. If anything, shadows will make it fade, instead, which is handled multiplicatively.

[quote="Chris"]while something like a black hole or bottomless pit may want to absorb all light regardless of source).[/quote]

This is exactly what I would want.

Honestly, I'm thinking of giving this a try and just seeing how its done with dynamic lights first, and see if I can at least get it working before considering other things. However I have no idea on how to do it Rachael's way in particular, as I'm not at all familiar with how lights and such work currently so I'll have to do a lot of digging for this.

I don't think there could possibly be a realistic model of negative light. I doubt wave cancellation would work with light waves like it works with sound waves, since it'd just result in twice as many photons.

[quote="Rachael"]If this is implemented I would prefer a multiplicative glow (0.0-1.0) instead. The hue does not need to be reversed for that.[/quote]
Depending on the desired effect, that may not be a suitable alternative. If you want to create something that takes away a fixed amount of light, in a similar way to how a normal light adds a fixed amount of light, a 0-1 multiplier won't work as it would take away an amount of light dependent on the light already there. It would also be subject to ordering issues, since applying a multiplicative light after all other lights will be different than if it's applied after sector lighting but before dynamic point- and spot-lights; different people could want different behaviors for different purposes (e.g. faux light occlusion should only affect static map lighting, not dynamic lights that may point directly at it, while something like a black hole or bottomless pit may want to absorb all light regardless of source).

I really really hate how subtractive lights work, especially with the way it tries to flip the hue in order to make it match the original light color (incorrectly, even).

If this is implemented I would prefer a multiplicative glow (0.0-1.0) instead. The hue does not need to be reversed for that.

I agree, that would have been useful a number of times.

Much like subtractive dynamic lights, subtractive glows would behave inverse of regular glows. Currently there's no way to do this but it would be nice to have a controllable height because right now, the only way to do this is by using Doom64 lighting - but you can't control how high it goes.