View Full Version : Carmack and Sweeny Interview

02-01-06, 01:49 PM
Hope it has not been posted before and that it is the right section if yes then mods please move/delete the thread .

Link : http://www.beyond3d.com/#news27836

Since the release of ATI’s X1000 series of products we’ve seen a couple of different takes on Shader Model 3.0 from the two main vendors. The first caused a small controversy with NVIDIA clearly believing Vertex Texturing to be part of the VS3.0 specification, but ATI (and apparently Microsoft’s WHQL certification process) disagreeing such that this wasn’t included in the X1000 series, with “Render to Vertex Buffer” being provided as an alternative. Another divergence has been highlighted with the recent X1900 release and ATI keeping a comparatively low number of texture units in their high end, whilst scaling up their math processing capabilities significantly.

We’ve quizzed both id Software’s John Carmack and Epic’s Tim Sweeney on their thoughts on these differing directions between the two vendors:

In our interview with Eric and Richard of ATI they mentioned they went in the direction of tripling the ALUs versus the TMUs after talking with you for instance. My question would be: do you see this as a good direction? Are you working on shaders which require a lot of ALU while keeping TMU usage constant to today?

John: I think it is clear that the ratio of math to texture fetches is increasing.

Tim: It's a definite trend that ALU usage in shaders is going up at a faster rate than TMU usage, so it's reasonable that the hardware should increase ALU's faster than TMU's. What ratio is ideal is debatable; it depends on a whole lot of variables, but fortunately it's easy to see whose tradeoffs win at a given price level by running some benchmarks.

The X1000 series of ATI cards don't implement an actual texture fetch in the vertex shader, unlike NVIDIA's GeForce 6 and GeForce 7 series, preferring instead to get the texture information from a vertex buffer that the programmer has to setup in the pixel shader. Which implementation do you prefer?

John: For vertexes, I think more often about looking up data in a table rather than indexing an image, but I can see either perspective.

Tim: We don't use vertex texture fetch in UE3 right now, but I expect we'll be using it in the future for moving more of our displacement-mapped terrain logic to the GPU.

Tim also dropped the following comment to us with regards to Unreal Engine 3:

Tim: We'll be making a UE3 benchmark available several months before shipping UT2007 on PC, in order to encourage the hardware folks to optimize their drivers. We're not doing this now, because at our stage in development many aspects of our rendering pipeline aren't fully optimized, and if we encouraged IHV's to optimize for it now (by releasing a benchmark), they would end up wasting a lot of time optimizing code paths that aren't reflective of a final, shipping UE3 project. Regarding the timeline, we'll be actively developing Unreal Engine 3 throughout the current hardware generation -- all the way through 2009.

02-01-06, 02:11 PM
Nice! :D Thanks, my 2 favorite dudes in the industry... heh :)

02-01-06, 02:32 PM
Hehe , mine too :D . And you even have the Unreal box signed by Sweeny :o , I wish I had that :rolleyes:

Btw I read the new PC gamer Carmack interview , it was nice and it seems like the work on the new engine is running pretty fine . I will just give some quotes

" PCG : Are you working on a new rendering engine ?
JC : yeah for the last year , I have been working on new rendering technologies . It comes in fits and starts our internel project that'll incorporate it hasn't been publically announced . We are doing simultaneous development on Xbox360 and PC and we intend to release on playstation 3 simultaneously as well . But its not a mature enough platform right now for us doing to be much work on .
We're starting to see some really spectular results out of this , as everyone climbs up the skill curve of using these new tools . The technology we're working on here at ID takes that step farther , with a terrain-texturing system that's applied throughout for everything ."

At the end he said , "We'll release large chunks of source code for people to hack up anyway they want. I intend to continue my practice of releasing complete engine code sometime after our next game is out , I may very well be releasing the Doom 3 source code ."

02-01-06, 04:06 PM
JC giving his tech back to the industry and to those dev's without a publisher and huge budget.

Gotta love the Carmack!!!!!

P.S - I cant wait to hear about there new IP (JC said it would'nt be a sequel to any existing ID title) and engine - should be everything the Quake Wars engine is and much much more!!!

02-01-06, 05:25 PM
P.S - I cant wait to hear about there new IP (JC said it would'nt be a sequel to any existing ID title) and engine - should be everything the Quake Wars engine is and much much more!!!

I image this engine to be on the level of the new crytech engine if not better.

02-01-06, 08:26 PM
JC said that Quake Wars will be similar to the new engine, but the new engine will have even more advanced features :)

02-01-06, 08:36 PM
If that's the case then I can't wait to see it running. Hell, I can't even wait for Quake Wars lol.