Radiosity

[Charon]

Anybody know if JC plans on using radiosity in Doom3. I know it was used in Quake2, but people complained that it made the shadows too dark, which would be perfect for Doom. (/me laughs devilishly)

I hope he uses it, though I think he is planning realtime lighting, which might not make radiosity a viable option.

[Zaldron]

??
Radiosity in Quake made dark shadows?? As far as i know, Q2 engine was capable of handling light bounces, so there´s no way you could archive dark rooms like in Quake I or Thief.

[Charon]

That's what I would think to. I am not saying I agree with this statement, that's just what I heard. I think radiosity is a great thing, I loved working with Lightscape when I had it.

[Zaldron]

Well, if Carmack´s working on pixel shaders, i doubt he would implement a pixel definition ray caster just to add radiosity. I mean, Q2, Half-Life and others made every lightray bounce like 50 times (ever saw a pointfile when searching for a leak?). The new engine would calculate 2 things before outputting every pixel.

1. What light sources could affect the pixel. Looks for lights, and discard those who are blocked by geometry.

2. Adds into the equation the fake pixel "slope" result of the bumpmapping.

That´s all, then it draw the colored point ranging it´s intensity from 0 (absolute dark) to 255 (texture real color). If the engine would be forced to calculate indirect lightning, then you´ll have to "compile" each visible frame 60 times per second.
Anyone here ever compiled a big map in Quake engines? The system takes an hour - one whole night to process all the data.
DooM 3 average polycount will be much bigger than Q3A one. Imagine.

Remember that radiosity is processor related, not even T&L hardware can help in this matter. Bogging down the CPU with this process would cut away 70% of raw power. Unless Carmack develops some strange algorythms that can handle such monster (very unlike), lightning would be direct.

[PainElemental]

Lighting isn't only CPU related, GeForce has an OpenGL extension called NV_register_combiners. With it, you can calculate real-time phong shading, dot3 bump mapping and so on. So you can only pass the light pos to the card and it makes all the calc stuff. And you know, in 2 years the cards will be a LITT&LE bit more powerous.

[Zaldron]

NV_register_combiners will be used, im pretty sure. But that instruction can´t understand D3 brush system. The cummulative effect of indirect lightning can´t be processed by HAL here.
You´re right, tomorrow´s graphics card will prove to be incredible powerful, but JC had already told us that GeForces, TNTs & Voodoos will be able to run the game.
The instruction needed for the calculation will never be implemented on video cards because it´s too much engine specific.

[PainElemental]

There are ways to use NV_register_combiners for the cummulutive effect(multitexturing? like more lightmaps on a face?). Or the card calcs the LMs for every light and face, stores them in textures like normal ones, and then, only when the light moves, the LMs are changed. Then using multitexturing they are drawn on the faces...

[DiSTuRBeD]

Zaldron said:

Keep in mind, the lighting should only need to be performed for ONE room at the time, not the whole map. in addition, it will porlly run mainly on the 3d card and not cpu, so it should work just fine =)

[Dima]

Zaldron said:

NV_register_combiners will be used, im pretty sure. But that instruction can´t understand D3 brush system. The cummulative effect of indirect lightning can´t be processed by HAL here.
You´re right, tomorrow´s graphics card will prove to be incredible powerful, but JC had already told us that GeForces, TNTs & Voodoos will be able to run the game.
The instruction needed for the calculation will never be implemented on video cards because it´s too much engine specific.

Zaldron not to offend or anything but where the FUCK did u read that the Voodoo,Geforce,TNT will work fine?!?!
The VE interview didn't say it!
He said that TNT 2,Voodoo 3 WON'T WORK AT ALL!
And even today's most powerful cards such as Geforce 2 Ultra will have to run at fairly low resolution with all options off to get some speed back but even then 60fps won't be archieved!!
Tommorow Card's will run the engine fine (I hope) but today's cards (Geforce 2 Ultra) NO WAY!!

[Zaldron]

You got me wrong, Carmack said that these cards will barely run the game. Except the GeForces, where you just need to drop some features. My point was that if Carmacks codes the entire luminosity subsystem based upon one GF2 instruction. Then the competition (3dfx, ATI) won´t be able to run the game except emulation (iak!). A good engine makes the calculations by it´s own, and then render the results depending the API. ONLY when it´s a special feature the correspondent code can be written under "special" functions.

[PainElemental]

Yeahh, I had the idea...
The game only tests if the NV_register_combiners are supported and then uses them for lighting calcs. If not, it uses the good old CPU for the ray-tracing or even radiosity(!).

[Dima]

Zaldron said:

You got me wrong, Carmack said that these cards will barely run the game. Except the GeForces, where you just need to drop some features. My point was that if Carmacks codes the entire luminosity subsystem based upon one GF2 instruction. Then the competition (3dfx, ATI) won´t be able to run the game except emulation (iak!). A good engine makes the calculations by it´s own, and then render the results depending the API. ONLY when it´s a special feature the correspondent code can be written under "special" functions.

1)u are wrong again!!
Carmack said that this cards won't have enough fillrate to play the game (that the game won't work on them at all)!!
2)If GF 2 ULTRA will run the game as badly (if at all) like I described in my prevous post then Geforce 1 won't run the game at all also! (fillrate problem again)!
I suggest u reread the interview cause some of the things u said are mistaken!

[Charon]

Ok guys, let's cool down here, I didn't mean to start a flame war with this.

Here is the quote from JC's interview at VE:

The ideal card for DOOM hasn't shipped yet, but there are a couple good candidates just over the horizon. The existing cards stack up like this:

Nvidia GeForce[2]: We are using these as our primary development platform. I play some tricks with the register combiners to get a bit better quality than would be possible with a generic dual texture accelerator.

ATI Radeon: All features work properly, but I needed to disable some things in the driver. I will be working with ATI to make sure everything works as well as possible. The third texture unit will allow the general lighting path to operate a bit more efficiently than on a GeForce. Lacking the extra math of the register combiners, the specular highlights don't look as good as on a GeForce.

3DFX Voodoo4/5, S3 Savage4/2000, Matrox G400/450, ATI Rage128, Nvidia TNT[2]: Much of the visual lushness will be missing due to the lack of bump mapping, but the game won't have any gaping holes. Most of these except the V5 probably won't have enough fill-rate to be very enjoyable.

3DFX Voodoo3, S3 Savage3D/MX, Matrox G200, etc: Without a stencil buffer, much of the core capabilities of the renderer are just lost. The game will probably run, but it won't be anything like we intend it to be viewed. Almost certainly not enough fill rate.

and here is the link: (look down towards the bottom of the page)

http://www.voodooextreme.com/games/interviews/carmack/2.html

So we see that everything down to a Voodoo3 will run the game, but some won't run it very well.

[Zaldron]

PainElemental said:

Yeahh, I had the idea...
The game only tests if the NV_register_combiners are supported and then uses them for lighting calcs. If not, it uses the good old CPU for the ray-tracing or even radiosity(!).

Yes, that´s my point
And Dima, if you see the extract from the VE that Charon copied here, you´ll see that these cards would RUN (not PLAY, just RUN the .exe) even if you have to deactivate all the features.
Of course im not recommending Geforces, Voodoos and Radeons to play this game. They suck compared to D3 demands. I only pointed that are enough to run the game.
For example, when Quake 3 launched, if you hadn´t a special 3D graphics card, you´re screwed. Im hoping that these great hardware jumps never repeat again.

[Dima]

ok ok I got u!
Sorry I misunderstood!
I just want D3 to be a MUCH bigger difference in graphics than Unreal once was!

[Zaldron]

Me too. D3 is the next jump. When Wolfenstein turned DooM, the world was amazed. We passed from 2D enviroments to 2.5D. When DooM turned Quake, iD again amazed us with new technollogy. We passed from 2.5D to 3D. Now, the challenge is greater. If iD´s plan is to shock us again with cutting edge technollogy, they would must keep in mind that they can´t move from 3D. They have to innovate in the same field they have been working for the last 4 years.

I think JC get pretty mad when Unreal came out. So he made Quake3, who can beat UT engine anytime.