r_waterfalloff
r_slimefalloff
r_lavafalloff 

But lava glows on its own. So does slime, doesn't it? 

I don't think slime necessary glows or doesn't glow, though it depends on what kind of slime it's supposed to be...

In Lava's case, you'd never realistically be able to see underneath the "surface" so no one can say if it glows or not :P

I feel like this effect could already be possible with negative lights - those subtract from the lightmap right? You could place a bunch of them underwater and it'd probably be possible to have the desired effect. 

Never knew they exist... 

I've never tried using them myself but it's in the docs. 

I was thinking of Quake 2 where (all?) liquid textures had surface light. So I guess that's actually irrelevant.

Quake's palette shifting effect tends to make underwater areas too bright anyway but negative light would probably still help. 

Attenuate faster if the trace crosses a water surface.

How do you see this working with moving liquid bmodels? 

How do you see this working with moving liquid bmodels?

Let's follow the current standard:
"_shadow" "n"
If n is 1, this model will cast shadows on other models and itself (i.e. "_shadow" implies "_shadowself"). Note that this doesn�t magically give Quake dynamic lighting powers, so the shadows will not move if the model moves. Default 0.

Liquid faces from inline bmodel entities should only be taken in consideration if their entity's self._shadow is 1.

Shadows are, essentially, instant attenuation. Faster attenuation can be considered semi-related to shadows. 

source 

The volumetric water attenuation is certainly do-able; the raytracer is already set up to have side effects when a ray hits certain surfaces.

The latest stable release from last fall has "stained glass" support, i.e. if you make bmodel with "_shadow" "1" and "_alpha" "0.5", light rays going through the entity will be partly attenuated and pick up the color of the texture.

So a simplified version of water attenuation would be not considering the distance traveled underwater, but just attenuate the ray when it goes through the surface. But on the other hand, I can imagine it would look cool to have bright sunlight at the water surface fading to black (thinking of an e1m4 type environment).

Anyway it's a cool idea to add to the todo list. My first priority now is fixing the breakage that Pritchard reported a while back, which I'm making good progress on but kind of a bit drained on tbh. 

That's fine, just know that what you are doing is really really great! There is no going back to the old tools now.

Incidentally, is your light or qbsp multithreaded? I know vis is, which changed light to be my current bottleneck (bounce fun notwithstanding). 

Thanks, appreciate it :)

Light is multithreaded, qbsp is not. Qbsp could get a lot faster, it spends most of its time in CSGFaces checking if each brush intersects each other brush in the map. Quake 2's qbsp is multhreaded.

The main performance tip for light is to avoid using -extra or -extra4 except on your final compile, and also add -gate 0.1 or something to reduce the overhead of delay 2 lights. 

Thanks!

No problem, I can wait. 

Idea:
When a map is recompiled, compare its entities with the entities in its previously compiled BSP file, and use the radius of each light to determine which surfaces had their lighting changed.

This way, when recompiling lights, the light tool can simply copy all unchanged lightmaps from the BSP file, and compile only the modified lightmaps rather than recompiling all lightmaps.

Bounce lighting can make this complicated, so I'm not sure if it would be possible. 

I feel like if you're testing within each light's radius to see what brushes have changed, you're already doing a lot of the grunt work for compiling a new lightmap...

It could work for a rough and messy sketch if you were willing to let a lot of edge cases slip through and accept the odd corrupted face or two, but then you invite the possibility of someone releasing a map compiled with that option turned on... 

testing within each light's radius

Only for the light entities that changed. Quite often, it will be only 1 light. 

What I've been thinking of, that's sort of related to that, is making a light preview tool; it would be a small GUI application with a 3d view with WASD+mouselook. You would open a map file and the tool does qbsp and light and displays the result, except the light baking is done on faces near the camera first, and the 3d view updates as each face finishes baking. Then it would refresh whenever the .map file is re-saved. I think this would be pretty sweet. 

yeah, what I have always wanted is a tool that lets me edit the lighting in realtime. I think that a diff-based approach to recalculating lightmaps would be fast enough to make this possible. Most edits would only affect one light, which has only local effects. Of course editing the sun values would not be as easily optimized. 

I'm not really sure what happens if you use old light data on a new BSP, but wouldn't it be pretty broken if you edited the brushwork around a light that hadn't changed. Say you made a ceiling, put a light on it, ran qbsp/light, then built the rest of the room and tried to patch.

I don't know what that would look like but I imagine it'd be quite bad... 

Yeah, that would be quite broken.

There are also complexities around light styles, combining lights with the same style, and packing in new lightdata/updating light offsets, which may in theory require to recalc for the entire BSP. 

Question: Does ._phong work across multiple entities when combined with ._shadow, to make multiple func_wall, func_illusionary, etc blend smoothly with the world's func_detail "entities"?

Right now I'm on mobile and can't test it. 

Pretty certain it does mankrip 

Iirc, separate func_detail / group will be blended if the _phong settings allow it. But other bmodels never blend with each other or world. 

Having a real time lighting renderer like ericw would be really neat. If you were able to cull light calculations to the player's view (You'd have to be very generous - bouncing their view around corners to find lights that should cast but would otherwise be missed), you could potentially have an engine that displayed in the traditional quake style, while keeping the main benefits of lighting in real time like moving lights.

I can already imagine a whole set of horrendous edge cases arising from this sort of thing, but it'd be a pretty neat thing to see and something that I'd hope modern computers would have the power to pull off... 

I have ZERO issue in paying for a light preview tool to be created. Even if its separate from TB.