So In Terms of Polygon Performance The X800 Beats Xenos

[pso]

pso, you´re wrong, RSX can SET UP 1.1 billion polygons per second, more than the double of Xenos´s theoretical limit. G70 can setup 2 polygons per cicle, and at 550MHz, that´s 1.1 billion.

I stand corrected then, no problem.

 

[Megadrive1988]

ATi's spec sheets say the X800 pumps out 700 million vertices per second. If 1 vertex = 1 polygon then that's 700 polygons per second. Since the Xenos can only do 500 million polygons per second, that's 500 million vertices per second. So the Xenos is weaker than an X800 in polygon performance.

there's more to it than that.

Xenos can actually rasterize and display 500 million textured vertices/polygons per second with some level of pixel shaders - in realworld situations. 90% of this should be possible in games (450 million)

in the same comparison, in realworld situations with pixel shaders, the Radeon X800 and X850 might struggle to sustain 100 million vertices/polygons in the realworld, in games.

the 700 million figure for X800 is maximum amount of transformed vertices per second - not the amount of polygons it can fill, light, shade and display on screen. if we compare this (the transformed figure) to what Xenos can do, it's 6 billion (or 6000 million) transformed vertices/sec. - both figures are kind of useless. but it shows us that Xenos is much more powerful

the fact is, Xenos will be able to render and display many more polygons per second (400 to 450 million) in games than Radeon X800 or X850 can (100 million or less)

 

[Titanio]

the 700 million figure for X800 is maximum amount of transformed vertices per second - not the amount of polygons it can fill, light, shade and display on screen. if we compare this (the transformed figure) to what Xenos can do, it's 6 billion (or 6000 million) transformed vertices/sec. - both figures are kind of useless. but it shows us that Xenos is much more powerful

While I agree that Xenos is more powerful, this doesn't really show that. All this shows is that Xenos can bring all of its self to bear on vertex ops while X800 can't This comparison does not account for everything else the X800 is doing on the pixel side that Xenos could not if it invested itself wholly in vertices...

A small point, I guess, since these figures don't really tell us much!

 

[Megadrive1988]

While I agree that Xenos is more powerful, this doesn't really show that. All this shows is that Xenos can bring all of its self to bear on vertex ops while X800 can't This comparison does not account for everything else the X800 is doing on the pixel side that Xenos could not if it invested itself wholly in vertices...

A small point, I guess, since these figures don't really tell us much!

you're right, the 6 billion (6000 million) verts/sec figure does not show anything useful as far as a good comparison between Xenos and Radeon X800.

however, the 500 million figure (with 90% efficiency giving us 450 million) does take into account pixel operations as well as triangle setup. the Radeon X800, I think, would be hard pressed to do 100 million. even if I am a little bit wrong, and we are generous to X800 by giving it 200 million, the Xenos is still over twice as powerful in polygon performance while at the same time being able to provide plenty of pixel processing / shading performance.

 

[Titanio]

you're right, the 6 billion (6000 million) verts/sec figure does not show anything useful as far as a good comparison between Xenos and Radeon X800.

however, the 500 million figure (with 90% efficiency giving us 450 million) does take into account pixel operations as well as triangle setup. the Radeon X800, I think, would be hard pressed to do 100 million. even if I am a little bit wrong, and we are generous to X800 by giving it 200 million, the Xenos is still over twice as powerful in polygon performance while at the same time being able to provide plenty of pixel processing / shading performance.

I'd agree on this, except to say the definition of "plenty" may vary. I don't think too many next-gen games will have the (relatively low) level of pixel shading required that's been estimated as allowing Xenos to sustain 500m polys per sec on screen.

Its irrelevant to the comparison, though. I suppose a more satisfactory comment might be that Xenos could sustain a substantially higher vertex rate given a certain level of pixel and vertex shading than X800 (a sufficiently complex level at that).

 

[richardpfeil]

We have no definite figures, but it seems very probable that the RSX will be able to set up triangles at twice the rate of the Xenos. But at that rate the vertex shaders can only run four instructions (vec4+scalar) per vertex. Not enough to get anything interesting done, except for particles. Particles are naturally simpler, and they are the reason why the set up rate is so high. Character models will never need 1.1 billion vertices set up per second, but particles will at times.

The Xenos has a solution for it's lack of a second rasterizer (in the case of particles). It can accept quads (rectangles). I'm not sure if the RSX (G70) can. If the rasterizer can only handle triangles, then every particle will need to be split in two, in effect halving the set up rate.

One more thought. The vertex shaders of the RSX may not be able to keep up with rasterizer set up, but with help from the SPUs in the Cell a clever and industrious programmer might be able to push that limit pretty hard.

 

[Wunderchu]

We have no definite figures, but it seems very probable that the RSX will be able to set up triangles at twice the rate of the Xenos. But at that rate the vertex shaders can only run four instructions (vec4+scalar) per vertex. Not enough to get anything interesting done, except for particles. Particles are naturally simpler, and they are the reason why the set up rate is so high. Character models will never need 1.1 billion vertices set up per second, but particles will at times.

The Xenos has a solution for it's lack of a second rasterizer (in the case of particles). It can accept quads (rectangles). I'm not sure if the RSX (G70) can. If the rasterizer can only handle triangles, then every particle will need to be split in two, in effect halving the set up rate.

One more thought. The vertex shaders of the RSX may not be able to keep up with rasterizer set up, but with help from the SPUs in the Cell a clever and industrious programmer might be able to push that limit pretty hard.

interesting info, some of which I wasn't aware of.. thanx richardpfeil

 

[Alpha_Spartan]

kinda funny how MS hasn't marketed 6 Billion Vert/sec.

Well, keep in mind that MS introduced their figures first and dictated the specs sheet. Sony just did a bullet-by-bullet comparison to MS sheet. However, they strangely left off the polygon/vertex throughput. I wonder why...

 

[scooby_dooby]

any specs that were lower than the 360 were left out, for example,the number of shader pipelines for the GPU is not in the official specs for PS3.

 

[Titanio]

The Xenos has a solution for it's lack of a second rasterizer (in the case of particles). It can accept quads (rectangles). I'm not sure if the RSX (G70) can. If the rasterizer can only handle triangles, then every particle will need to be split in two, in effect halving the set up rate.

Can you elaborate a little? I thought all GPUs boiled everything down to triangles. If Xenos did rasterise quads directly (not as two triangles), we're still none the wiser as to what its performance with that is, though (vs triangles).

Well, keep in mind that MS introduced their figures first and dictated the specs sheet. Sony just did a bullet-by-bullet comparison to MS sheet. However, they strangely left off the polygon/vertex throughput. I wonder why...

MS left the vertex transform rate off their sheet too. If you're talking about triangle setup, I doubt RSX's figure is less than 500m tris (?)

 

[richardpfeil]

Can you elaborate a little? I thought all GPUs boiled everything down to triangles. If Xenos did rasterise quads directly (not as two triangles), we're still none the wiser as to what its performance with that is, though (vs triangles).

I have a clear memory of reading about quads in the Xenos rasterizer, but now can find nothing about it. I may be smoking something on this one.

 

[Alpha_Spartan]

pso, you´re wrong, RSX can SET UP 1.1 billion polygons per second, more than the double of Xenos´s theoretical limit. G70 can setup 2 polygons per cicle, and at 550MHz, that´s 1.1 billion.

Where's your proof?

 

[Alpha_Spartan]

MS left the vertex transform rate off their sheet too. If you're talking about triangle setup, I doubt RSX's figure is less than 500m tris (?)

You doubt or you hope?

 

[Farid]

Where's your proof?

You doubt or you hope?

What kind of replies are thoses exactly?

If you think someone is making an incorrect statement, post your justification, and make your own point from that. Posting stuff like "Prove it!" and leave it at that is considered as being "noise" and therefore can (and will) be pruned.

People should contribute in a positive manner to any discussions, by either addressing a point or by bringing another point (On the topic).

 

[Hardknock]

I understand where you're coming from Vysez, and I guess he could have asked more tactifully. But I'm curious aswell where Almasy is getting his figures from?

 

[rabidrabbit]

Well, keep in mind that MS introduced their figures first and dictated the specs sheet. Sony just did a bullet-by-bullet comparison to MS sheet. However, they strangely left off the polygon/vertex throughput. I wonder why...

Where can I find the official specs for PS3 including RSX?
I thought they have yet to be published as the RSX had not been finalised.

 

[Mintmaster]

People should contribute in a positive manner to any discussions, by either addressing a point or by bringing another point (On the topic).

Agreed about Alpha_Spartan's second comment, but the first (questioning RSX's set up rate) is quite valid. I haven't seen much evidence for G70 having twice the setup rate. Throughput tests, like here and here (geometry-only and 1-light tests) don't show any improvement from NV40 beyond clock rate increases.

In any case, we should ask ourselves: Where do game developers want to increase polygon density the most? Yes backgrounds are more detailed, but they still have a high pixel to polygon ratio, so a high geometry rate doesn't help much here. The answer is character models. Artists would love a 100,000+ poly budget for faces. Characters also need to be skinned, requiring more complex vertex shaders than just a single matrix * vector operation.

Now, going back to pixel to poly ratio, when is it lowest? When there are NO pixels, of course! The back sides of characters (i.e. what you don't see), as well as parts outside the viewing frustum, are full of vertices that must be crunched through as fast as possible. Xenos can fly through these skinned vertices with 48 shader units (remember, no pixels to be shaded), while RSX has only 8. This is the sort of thing that makes a unified shader architecture so efficient.

Practically speaking, Xenos will have far more geometry processing power than RSX, more so when the going gets tough with longer vertex shaders. Even if RSX can indeed set up 2 triangles per clock, it will likely only win (in terms of geometry) in simple, theoretical tests.

Finally, remember that there is only finite bandwidth with which one can transfer vertex information. A typical vertex may be 40+ bytes (position, normal, tex coords, blend weights, indices), and would need 45+ GB/sec to sustain 1.1 GVerts/sec.

 

[jvd]

I think normal maps will be the big thing . Those e3 videos from 2004 have the epic guys talking about 200 million polygon buildings and backrounds being made into 2 million polygon normal maps and keeping almost the smae quality . Character models wont benfit as much as you can still see blocky body parts however with a higher polygon count and normal maps that should be reduced. This generation will be more about shaders imo

I think for both the rsx and xenos this will reduce the need for insane polygon counts

 

[Farid]

Agreed about Alpha_Spartan's second comment, but the first (questioning RSX's set up rate) is quite valid.

I wasn't questioning the validity of the comments but only the manner those comments were phrased.

 

[hasanahmad]

I think normal maps will be the big thing . Those e3 videos from 2004 have the epic guys talking about 200 million polygon buildings and backrounds being made into 2 million polygon normal maps and keeping almost the smae quality . Character models wont benfit as much as you can still see blocky body parts however with a higher polygon count and normal maps that should be reduced. This generation will be more about shaders imo

I think for both the rsx and xenos this will reduce the need for insane polygon counts

link