So In Terms of Polygon Performance The X800 Beats Xenos

Who is making that assertion? Be careful not to confuse people giving a theoretical spec vs. people saying xyz amount will be running in a game.

 

If you download NV CineFX 4 Technical brief (You have to search their page for it, don't have direct link) Under Vertex Shader, there is a sub heading "Faster Triangle Setup". However it doesn't say by how much it is faster compare to CineFX 3. But it seems its one area that they make improvement on.

If you read most of NV performence presentation, triangle setup been the limit to higher polygon count, since according to them triangle setup scale with clock speed and they can't bolt another triangle setup unit, like they can with Vertex Shader unit.

 

Alpha_Spartan - I am fairly confident in saying that I think RSX and Xenos are both going to be rasterizing / drawing / displaying a few hundred million polygons (~300M) in games when all is said and done. this ~300M polys should include lighting and some decent pixel shaders, normal mapping, etc, and we will see this in 3rd-4th generation games. whereas first generation games will probably around 75-150 polygons (the peak paper specs of current consoles)

I don't think we've seen any game on PS2 or Xbox that pushes more than 20-25 million polygons. the majority of games this generation (DC, PS2, Cube, Xbox) have been under 10 million.

 

Yes. Very good mentality.

 

That's what I was talking about before. Alpha_Spartan keeps going back to how the G70 is beating the Xenos, but what does it matter if the games never go anywhere near that limit? Am I misunderstanding something?

 

I'm sorry but i'm green in therm of counting perfomance can someone explain me where did come from 6 bilion number????
smthng x smthng x smthng = 6 billion ..... but what???

 

the 6 billion number, as I understand it, is the peak theoretical amount of *very* simple polygon transforms that the Xenos graphics processor can do per second, if all the sub-processors within Xenos are focused on geometry alone. this does *not* mean Xbox360 can display 6 billion polygons per second or anywhere near that number. It is merely an interesting math fugure that really has no bearing on what Xbox360 games will be doing.

Xenos' peak polygon setup figure is 1/12th as much as that 6 billion figure. which is a small fraction of 6 billion. it is the 500 million figure that is really relavent here. and of that (500M) we will see a fraction of it used in first-generation Xbox360 games. lets say 100M. as Xbox360 gets older, programmers will make more and more use of the max 500 million polygons that Xenos can setup, but probably never 100% of it.


edit: sorry, I re-read the post and I see it is asking how did they arrive at the 6 billion figure, sorry I'm no good at math. it's obviously got something to do with the 48 shader ALUs * 500 MHz but I dont know what other calculations are involved. sorry

 

How was obtained the number of 6 billion? if in the article of speaking Hiroshige Goto and slides of the M$ that using about 24GFlops one has 500 million poligons/sec (48 flops to per poly? ). Therefore most reasonable it would be to believe that with 240GFlops programmable of the R-500/C1/Xenos pps reached 5 billion (unless it has some unit fixed function that it processes others 48GFlops/1 billion pps...).

 

The minimum vertex transformation takes 4 cycles to execute on a Xenos's ALU, so
Xenos can transform (48 ALUs * 500*10^6)/4 cycles = 6*10^9 vertices per second.
I'm assuming Xenos has some extra hardwired function to perform trasnformed vertices projection, otherwise the minimun shader would likely be slower than that.

 

The problem with the 6 billion vertices number is that there's not enough bandwidth (at, say, 20 bytes per vertex = 120GB/s) for it to be meaningful.

Also, if Xenos normally performs a z-only pre-render pass (which is a given for 720p with AA turned on), then the number of effective triangles it can process is halved - i.e. the set-up rate becomes 250M triangles/s (though, obviously, the peak instantaneous rate remains 500M triangles/s).

Of course vertices/triangles transformed does not equal the number of triangles set-up - viewport clipping and backface culling means that far more triangles are transformed than are set-up.

I don't know typical real-world proportions (transformed:set-up) for various game engines, though. There must be some data out there...

Jawed

 

Oh Yeah and I am thankful for the reply.

 

The bandwidth problem would be ameliorated when Xenos performs tessellation.

Jawed