Doom needs... LIGHT!

[Aardappel]

Ok, a brainfart from yours truly.

It occurred to me that a lot of recent Doom levels have really cool architecture, but often still look bland and boring because of lighting. Good lighting in a game/engine improves the looks of maps soooo much, that it seems worth investigating if the lighting in Doom engine can be improved, if possible while being largely compatible with old wads. I see two possibilities:

Full vertex lighting. This one is fully compatible with existing wads, is extremely easy to implement, and is bound to make Doom wads look a lot better. All GL ports already use vertex lighting to render the Doom sector based lighting, but could do better with the same information. Basically what you'd do is for every vertex on the map compute the average light intensity for all sectors that touch it, so a vertex that is part of just one sector would just have that sectors light value, and one that sits on the boundary between two sectors would be averaged andsoforth. Now render as usual, only use the vertex light values instead of the sector light values when rendering the triangles, and you'll get smooth gradiants allover the place. Obviously this works best the more detailed a map is, and especially for those maps that already use lots of sectors purely for lighting. Maps that have big box rooms with occasional light level changes will look odd, but then again they looked odd in the first place. If you wanted to be really clever you could manually subdivide large walls to improve the effect but I doubt it is needed.

Second idea is more complicated but could look even better. The idea is straightforward: add wad entries for both real light sources and resulting lightmaps, much like the glbsp information. A seperate light program would be needed to compute those lightmaps, an editor needed to place the lightsources, and (GL) ports to render it. This could easily make doom look as gorgeous as quake2 lighting (maybe leave the colouring out though :). But this wouldn't be much fun if it were only for new wads. I think it is possible (but tricky) to generate lightsource information for existing wads by looking at the light level in sectors, i.e. for every sector of a certain size you would generate a lightsource that would illuminate it roughly the same. This can't be done perfectly, infact often it will be very different from the original. But does that matter? I don't think so. If you'd do radiosity lighting with a huge bounce it would look great in most situations. You'd treat sectors with a sky ceiling differently and give them sunlight etc.

Anyway, I thought I'd get a discussion going. Ideas welcome...

--Aardappel