Doom3: Will it have a separate SM3 codepath ?

[rms]

Hi, are there optimizations for Nvidia-specific features in this game? I seem to recall Carmack wanting all cards to run the same code.

rms

 

[KimB]

If so, it's sure to be efficiency improvements, though it'd also be kinda neat to implement some HDR rendering via a FP16 framebuffer.

 

[anaqer]

Out of the box - I don't think so.
In a later patch - quite possibly.

 

[AlNom]

what does SM3 have to do with opengl?

 

[Xmas]

Hi, are there optimizations for Nvidia-specific features in this game? I seem to recall Carmack wanting all cards to run the same code.

rms

There will be at least support for GL_EXT_depth_bounds_test, but that's not related to SM3 (or CineFX3).

 

[oddfellow]

what does SM3 have to do with opengl?

Was thinking the same thing

 

[Ostsol]

what does SM3 have to do with opengl?

Was thinking the same thing

Think of it as a set of capabilities. Technically, OpenGL already supports at least some of it (though GLSL).

EDIT: In any case, Doom 3 is sure to have some NVidia specific optimizations, as described by Xmas, as well as some for ATI, too. Two-sided stencil is one, for example, that is supported by different extensions on ATI and NVidia cards. Probably not SM3.0-level features, but there will be others.

 

[Zeross]

what does SM3 have to do with opengl?

Was thinking the same thing

Think of it as a set of capabilities. Technically, OpenGL already supports at least some of it (though GLSL).

Yep but given that Doom III is using ARB_VP & ARB_FP...
I think the only feature Carmack may be interested to add to Doom III is FP FrameBuffer, remember this quote :

The future is in floating point framebuffers. One of the most noticeable
thing this will get you without fundamental algorithm changes is the ability
to use a correct display gamma ramp without destroying the dark color
precision. Unfortunately, using a floating point framebuffer on the current
generation of cards is pretty difficult, because no blending operations are
supported, and the primary thing we need to do is add light contributions
together in the framebuffer. The workaround is to copy the part of the
framebuffer you are going to reference to a texture, and have your fragment
program explicitly add that texture, instead of having the separate blend unit
do it. This is intrusive enough that I probably won't hack up the current
codebase, instead playing around on a forked version.

Now that there is an "elegant" solution Carmack may be tempted to add it, it depends on the impact it would have on the code I guess since he seems to try to minimize the number of specific code paths (he didn't hesitate to throw the old NV30 code path now that GF FX performs good under the ARB2 path).

 

[Ostsol]

Well, I wasn't saying that Carmack will use it -- merely that there are at least some equivalents in OpenGL.

 

[Zeross]

Well, I wasn't saying that Carmack will use it -- merely that there are at least some equivalents in OpenGL.

He was fairly interested two years ago by GLSL on Wildcat VP, but since he seems to have used Cg. Maybe he is waiting for the drivers to mature a bit.

 

[AlNom]

wish JC would update his .plan more often than once a year

 

[Guden Oden]

What does D3 do that could be accelerated by SM3 anyway? He's already down to 1 rendering pass per light using plain DX9-level functionality...

Considering DX7 is enough to draw D3's graphics, I don't understand what you people expect really.

 

[AlNom]

make it liek tenebrae!!!!!!!!

....oh wait...nevermind....

 

[Cryect]

What does D3 do that could be accelerated by SM3 anyway? He's already down to 1 rendering pass per light using plain DX9-level functionality...

Well he could make it with SM3 fairly easily to do all the lights in one pass instead one pass per light.

 

[Dave Baumann]

What was JC's quote? "Doom 3 is designed around the features and capabilities of GeForce2 style products, my next engine will be designed around nv30/nv40".

 

[DeanoC]

What does D3 do that could be accelerated by SM3 anyway? He's already down to 1 rendering pass per light using plain DX9-level functionality...

Well he could make it with SM3 fairly easily to do all the lights in one pass instead one pass per light.

No he couldn't, same reason Crytek can't in many cases.

Stencil shadows are a bitch for collapsing lights into one pass. NVIDIA were saying this very thing at 6800 leagues.

Its one of the reasons many (including NVIDIA) believe that stencil shadows are an evolutionary dead-end.

 

[anaqer]

make it liek tenebrae!!!!!!!!

"Meak it look leik Tenebrae!!!11!!1" - classics should be quoted correctly.

 

[Waltar]

What was JC's quote? "Doom 3 is designed around the features and capabilities of GeForce3 style products, my next engine will be designed around nv30/nv40".

Fixed.

 

[tEd]

What was JC's quote? "Doom 3 is designed around the features and capabilities of GeForce3 style products, my next engine will be designed around nv30/nv40".

Fixed.

now you got it wrong :?

daves post didn't need fixing

 

[AlNom]

make it liek tenebrae!!!!!!!!

"Meak it look leik Tenebrae!!!11!!1" - classics should be quoted correctly.

*bow*

*claps*