An interview with ATI - Dave Baumann

[onethreehill]

AMD recently launched a new high-end graphics card. At the time of compiling this Q&A session, the card was not yet released, hence some of the questions are a little in the past tense.

The ATI Radeon™ HD 4890 (RV790) and is based on technology introduced in the ATI Radeon™ HD 4850 and ATI Radeon™ HD 4870 graphics cards (RV770). We figured it be a good time to sit down with a product manager of both that RV770 and RV790 chipset.

Our Q&A will be conducted with Dave Baumann. A name that might sound familiar to some of you. Dave Baumann was, at the time, the chief editor for Beyond3D. Back in 2006 he joined ATI (now part of AMD) as technical marketing manager.

Dave now is Product manager and both the RV770 and RV790 fell under his responsibility .........
http://www.guru3d.com/article/interview-with-ati-dave-baumann/

[ToTTenTranz]

Aaah, finally a decent PR interview.. You can tell this guy comes from tech forums!
Every company should pick these guys from forums! They know what they're talking about, they're enthusiastic about it and they love their jobs!


A small insight about the tesselator unit being used or not..
From what I could tell, if a programmer uses the full function DX11 tesselator, it won't work on ATI DX10 hardware. However, if the programmer writes the tesselation code for the ATI hardware, it will be compatible with all DX11 hardware.
It's a no brainer for me that the first DX11 games using hardware tesselation should be compatible with ATI's hardware, so that it's compatible with 3 year-old ATI cards.

[largon]

Given one can assume nV will go DX11 just as soon as ATi does I don't see why game developers would write specifically for ATi hardware. It wouldn't make any sense to shut out nV from getting tesselation to work on their chips. So I don't think the matter is a such "a no brainer".

[trinibwoy]

From what I could tell, if a programmer uses the full function DX11 tesselator, it won't work on ATI DX10 hardware.

Yep.


However, if the programmer writes the tesselation code for the ATI hardware, it will be compatible with all DX11 hardware.

Nope.


It's a no brainer for me that the first DX11 games using hardware tesselation should be compatible with ATI's hardware, so that it's compatible with 3 year-old ATI cards.

DX11 tessellation will not be backwards compatible. Check out this link for a great overview of the DX11 tessellation pipeline - http://www.gamedev.net/community/forums/mod/journal/journal.asp?jn=316777&reply_id=3424549

The fixed function bit may be similiar but the HS and DS stages are all sort of emulated via multi-pass vertex shaders on ATI's current implementation. And of course, the full DX11 functionality isn't there as a result.

[ToTTenTranz]

Given one can assume nV will go DX11 just as soon as ATi does I don't see why game developers would write specifically for ATi hardware. It wouldn't make any sense to shut out nV from getting tesselation to work on their chips. So I don't think the matter is a such "a no brainer".


DX11 tessellation will not be backwards compatible. Check out this link for a great overview of the DX11 tessellation pipeline - http://www.gamedev.net/community/forums/mod/journal/journal.asp?jn=316777&reply_id=3424549

The fixed function bit may be similiar but the HS and DS stages are all sort of emulated via multi-pass vertex shaders on ATI's current implementation. And of course, the full DX11 functionality isn't there as a result.



I never said DX11 tesselation is backwards compatible, or that developers should write their code for ATI-only hardware.

I said:
You write for DX11 tesselator -> works for DX11 hardware only.
You write for ATI DX10/DX10.1 tesselator -> works for every ATI R600/R700 hardware and also with every DX11 card out there.


The tessellation unit featured in the ATI Radeon HD 2000, HD 3000 and HD 4000 series are all very much based on the same functionality found in the XBOX 360 "Xenos" graphics chip, although the unit in the ATI Radeon HD 4000 series does feature some additional tweaks. For DirectX 11 the tessellation portion of the pipeline has also been wrapped with two new shader types that can be used, the Hull Shader and the Domain Shader. Although these are new stages in DirectX 11, my understanding is that the actual tessellation portion of the pipeline is highly leveraged from the Xenos capabilities; hence any tessellation work that a developer carries out on our current GPUs will be very easily portable to DirectX 11.

By "very easily portable" means that AMD could probably build an automatic compiler so that developers could easily have ATI DX10 compatible tesselation in their DX11 games.
Sure, the developers would lose some performance with that, but they would also have more performance on "older" AMD systems -> a little bit like what's happening with DX10.1 features right now.

[saaya]

good interview, but unfortunately no details, no specs, not even about current hardware... too bad.
just a lot of marketing talk...

[zanzabar]

Given one can assume nV will go DX11 just as soon as ATi does I don't see why game developers would write specifically for ATi hardware. It wouldn't make any sense to shut out nV from getting tesselation to work on their chips. So I don't think the matter is a such "a no brainer".

dx10.1 and dx11 require the same hardware so ati already has it on the hardware lvl and with software programmable shaders its not hard to add things to the cards like it is what hard programed shaders

[Caparroz]

Aaah, finally a decent PR interview.. You can tell this guy comes from tech forums!
Every company should pick these guys from forums! They know what they're talking about, they're enthusiastic about it and they love their jobs!

Dave Baumann was the founder of beyond3d, the XS of 3D graphics. :yepp:

It should be a great interview, I'll read it later when I have time. It's always nice to hear from Dave. Thanks for posting, onethreehill.

[trinibwoy]

By "very easily portable" means that AMD could probably build an automatic compiler so that developers could easily have ATI DX10 compatible tesselation in their DX11 games.

No, very easily portable means that if you design your art pipeline and engine to support tessellation using ATI's DX10 tessellation support you'll have an easier time porting it to DX11. It won't be automatic in any sense. Did you read the tessellation overview over at gamedev? That should make it clearer.