Editing and lighting

[Zaldron]

Well, since the lack of D3-specific related stuff on the forum for the last couple of days, I just wanted to bring back that old, wasted topic no one cares anymore : DooM 3

If I see another top ten I´ll shoot myself, no, not really, that would be too easy for you guys...

How will it be the level editing in D3? A hard question, because we have absolutely no clues about the editor workings. So I´ll just stick to the "methodes" of designing.

The most important change will be the how and the when for light placement. Back in the Quake 1 days there was a little trick to remember when placing lights : there´s no radiosity.

Since lightrays bounce off from surfaces (based on their reflective coeficients) it is obvious why even small lamps can lit up a whole room. Alas, why the Hell lights are so shitty on Quake!?!

Quake 1 lacked from radiosity, so every light casted a fair amount of lightrays wich collided and died at the very first face they encountered.
This worked pretty well for Quake, since the darkness and shadows were key elements for the atmosphere. Heck, if they went so far as making the pallete fully compatible with the all the brown&blue shades, they were going to use them.

But what happens when someone wants to make a properly lited room, here´s what he does : instead of placing 2, 3 lights, he makes a grid of them. Everytime you go outside on a game like Hexen II, there´s a big grid of lights, from 15 to 20 all next to the sky.
This was quickly and painless solved on Quake2/3, where the lightrays bounce several times making the whole place look a lot more like Reality, and made the light count go down heavily.
While the problem seems to be solved, it will once again resurface on the DooM3 engine, and this time it wont be easy to fix.

Imagine how slow and weird looking the grid-solution would turn to be? A miriad of soft shadows pointing to all directions, while your recently acquired GF3 spits 20 fps or less?

So, how can you do nice lited, comfortable rooms? You can´t. Perhaps by doing some weird stuff with shaders you´ll actually get somewhere (making surface´s "ambient light" slightly over 0)

Another interesting thing to note. Open sky areas. Carmack wanted to add directional lights on Q3A, so I´m pretty sure they´re available now. A directional light consists mainly in a set of lightrays paralel to each other, making a perfect susbstitute when dealing with light "sources" like the Sun.

Anyway, there´s no simple solution for those who want DooM3 to not be dark. It´s not a failure of the engine, but a tech problem. Unless you hook several GF3 together to do the calcs, or play at 40x30, of course...

Does anyone with more experience in editing than me knows some other troubles?

[Guest Kite]

Grid of lights? What FOR?

If guys from idSoft is smart enough they will make a real radiosity pre-processing and rooms will be lighten correctly with only a few lights. But shadows during the game will be calculated only from light sources, not from reflected light. Visual appearance won't be hurt much.

[Zaldron]

That´s the problem. There´s just ONE pipeline working. There´s no prestage lighting. Carmack´s not rendering shadows over lighting, but actually rendering points where there is light.

Besides, there are no static lights. Every light is movable and destroyable by default.

[Guest Dark_Fox]

Oh BOY!

[Zaldron]

Huh?

[Jayextee]

This doesn't anwer your question, but I'd sure like to see some way to make non-realistic lights, equivalent to sector lighting in doom, mainly for creative reasons...

[Guest CRiZ]

Yeah, I was wondering about that multiple shadows thing too. Aren't they're going to be a million shadows cast by every person and monster in the game? Like you said: it seems like that would take way too much processing power. Then again, you may be wrong... maybe the doom3 engine and a GF3 CAN handle that amount of number crunching.
If not, I was thinking that maybe only the most intense light hitting a player will cast a shadow. Or maybe every light that hits a player with more than 0.1 its original intensity (decaying at 1/r) will cast a shadow.
As for doing outside lights, I'm sure Carmack has written code for parallel ray lighting. The so-called infinite light sources. But you mentioned many posts back that portal technology is terrible for outside scenes so I doubt we'll have to worry much about the arrays of lights bringing down frame rate because there probably won't be outside levels anyway.

Are you sure about what you said about the lighting algorithm used for quake1 and quake2? I'm not doubting you, I just want to know for a fact because I'm writing a paper for a technical writing course on the evolution of Id Software's graphics engines. So, if I understand what you said: Quake1 used lighting where the rays stop at the first face they encounter. In quake2 the rays stop after about 3 faces or so? Do you know where I could read more about the guts of these engines? Thanks

[Zaldron]

Yeah, Quake 1 rays stopped at the very first triangle. Quake2 makes each ray bounce like 20 times or so. Make a level with a little leak (a path to the void) and count the average amount of times the light ray hits before warning you about the problem. Move the light to several locations to get different results.