ATI & Nvidia Duke It Out In New Gaming War

geek_on_a_stick writes "I found this PC World article about ATI and Nvidia battling it out over paper specs on their graphics cards. Apparently ATI's next board will support pixel shader 1.4, while Nvidia's GeForce3 will only go up to ps 1.3. The bigger issue is that developers will have to choose which board they want to develop games for, or, write the code twice--one set for each board. Does this mean that future games will be hardware specific?"

Comments

Simple way to help you choose

[Dr_Cheeks]

Just do what I do; utterly fail to save up for that latest bit of kit. Every game I've bought in the past year has supported my TNT2 M64 chipset. Sure, I can't render something like Shreck on my machine, but since I blew the graphics card money on beer I can't tell the difference.

Hell, Half Life and Doom are barely distinguishable from each other if your beer-goggles are thick enough. And it doesn't matter if the frame-rate slows down thru lack of processing power - your reactions are already terrible from the booze.

Yet again, beer is the cause of, and solution to one of life's problems (thanks to Homer for the [slightly paraphrased] quote).

Cutting through the hysteria...

[Tim Browse]

There seems to be a large amount of confusion as to what this means, and some people seem to be jumping off the deep end (as usual), so here's an attempt to clear up some of the issues.

(PS = Pixel Shader in the following points)

• DX8 Pixel Shaders use the PS API. Part of this API is a definition of a limited assembly language.
• A PS written for version X will run on drivers that support version Y if X <= Y - i.e. pixel shaders are backwards compatible.
• When new versions of the PS API appear, they mostly add instructions, or extend the register set. Hence the backwards compatibility.
• Hence any PS written for ps1.3 (e.g. a GeForce 3 card) will also run on a card supporting ps1.4 (e.g. ATI's new card).
• The ps1.3 shader may not run as fast as it could on the ATI card, depending on what features of ps1.4 it could take advantage of.
• If you try to create a PS on a gfx card that does not support PS, or does not support the minimum PS version required, then DX8 will not fall back to software to render the triangles. That would be madness - rendering would probably be an order of magnitude (or two) slower. The request to create the PS will simply fail. (NB. When using a vertex shader, DX8 can fall back to software for that, because it makes sense, and they have some reasonably fast software emulation for vertex shaders).
• You don't have to choose whether you write for nVidia or ATI - you choose what level of PS (if any) you are going to support. You can choose to support 1.3 and 1.4 with separate code paths if you want, to get maxiumum throughput from ps1.4 cards.

• Hope this makes things clearer.

  Pixel/Vertex shaders are an attempt to provide developers with low-level access while still maintaining the abstraction needed to support multiple sets of hardware.

  To be honest, compared to the issues of shader program proliferation due to the number/type of lights you have in a scene etc., this isn't that big a deal. You might as well complain that writing a PS that uses PS1.3 means that you're 'choosing' GeForce 3 over all the existing cards that don't support PS1.3. Or that when bump mapping was added to DX and you used it, you were choosing the cards that did bump mapping over those that didn't.

  DirectX is supposed to let you know the capability set of the gfx card, and allow you to use those capabilities in a standard way. The pixel shader mechanism is just another example of this at work.

  As ever with games development, you aim as high as you can, and scale back (within reason) when the user's hardware can't cope with whatever you're doing.

  Trust me, this is not news for games developers :-)

  Tim

Oh good. A pissing contest...

[Gingko]

First of all, a direct link to ATI's SmartShader tech introduction.

I have a few disparate thoughts on this subject, but rather than scatter them throughout the messages I'll put 'em all in one place.

ATI are attacking what is possibly the weakest part IMHO of DirectX 8 - the pixel shaders. Pixel shaders operate on the per-fragment level, rather than on the per-vertex level vertex shaders which were actually Quite Good. The problem with Pixel Shaders 1.1 is that, to paraphrase John Carmack, "You can't just do a bunch of math and then an arbitary texture read" - the instruction set seemed to be tailored towards enabling a few (cool) effects, rather than supplying a generic framework. Again, to quote Carmack, "It's like EMBM writ large". Read a recent .plan of his if you want to read more.

If you read the ATI paper, they don't really tell you what they've done - just a lot of promises, and a couple of "more flexibles!", "more better!" kind of lip-service. I don't care about reducing the pass number. Hardware is getting faster. True per-pixel phong shading looks nice, but then all they seem to do extra is allow you to vary some constants across the object via texture addresses. Well that's great, but texture upload bandwidth is can already be significant bottleneck, so I don't know for sure that artists are gonna be able to create and leverage a separate ka, ks etc map for each material. (I did enjoy their attempts to make Phong's equation look as difficult as possible)

True bump-mapping? NVidia do a very good looking bump-map. Adding multiple bump-maps is very definitely an obvious evolutionary step, but again, producing the tools for these things is going to be key. Artists won't draw bump-maps.

Their hair model looks like crap. Sorry, but even as a simple anisotropic reflection example (which again NVidia have had papers on for ages) it looks like ass. Procedural textures, though, are cool - these will save on texture uploads if they're done right.

What does worry me is that the whole idea of getting NVidia and Microsoft together to do Pixel Shaders and Vertex Shaders is so that the instruction set would be universally adopted. Unfortunately, ATI seem to have said "Sod that, we'll wait for Pixel Shader 1.4 (or whatever) and support that." I hope that doesn't come back to bite them. DirectX 8.0 games are few and far between at the moment, so when they do come out there'll be a period when only Nvidia's cards will really cut it (I don't think ATI have a PS 1.0 implementation, someone please correct me if I'm wrong) - will skipping a generation hurt ATI, given that they're losing the OEM market share as well?

I dunno, this just seems like a lot of hype, little content.

Henry

Performance benefits

[John Carmack]

The standard lighting model in DOOM, with all features enabled, but no custom shaders, takes five passes on a GF1/2 or Radeon, either two or three passes on a GF3, and should be possible in a clear + single pass on ATI's new part.

It is still unclear how the total performance picture will look.

Lots of pixels are still rendered with no textures at all (stencil shadows), or only a single texture (blended effects), so the pass advantage will only show up on some subset of all the drawing.

If ATI doesn't do as good of a job with the memory interface, or doesn't get the clock rate up as high as NVidia, they will still lose.

The pixel operations are a step more flexible than Nvidia's current options, but it is still clearly not where things are going to be going soon in terms of generality.

Developers are just going to need to sweat out the diversity or go for a least common denominator for the next couple years.

I fully expect the next generation engine after the current DOOM engine will be targeted at the properly general purpose graphics processors that I have been pushing towards over the last several years.

Hardware vendors are sort of reticent to give up being able to "out feature" the opposition, but the arguments for the final flexibility steps are too strong to ignore.

John Carmack