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| | Platform Comparison / A "Genuine" GC, PS2, Xbox Comparison | | Author | Message | | | September 12, 2002 - 10:59:21pm (edit: 12/15/02 - 11:02am) |
| Here's a few comparisons, I'll assume you have prior knowledge of the aforementioned platforms.
Geometry Rendering:
Gamecube
1. No hardware dynamic surface generation supported, geometry rendering is done on the CPU.
2. When running vertex engine, the Gekko can output a purported 1.9 GFLOPS, which translates into roughly:
1.9 GFLOPS / 19 FMACS / (vertices/poygon average) = 47,000,000 polygon max output. Multiply this by 2-4 (maybe more) for SIMD and your left with a great deal of theoretical performance. The CPU also does local lightings, custom geometry (vertex manipluations), and any other custom effects, and SIMD state changes cost time.
http://www.hotchips.org/pubs/HC01/06ibm-gekko.pdf
The seperate 128-byte FIFO Write Gather Pipe bursts the graphics data over the 1.2 GB/s bus to the GPU when its free. Vertex compression is used, onboard hardware convert SP FP numbers to 8 bit or 16 bit Signed or Unsigned Integers and vice versa, directly into the floating point registers.
100,000,000 x 32 bytes = 3.2 GB/s required
The 4:1 vertex compression boosts the total bandwidth to around 5.2 GB/s, total vertex output is unhampered by the external CPU bus.
Other possibilities exist. The Gekko could be run in multi-core mode, with half of the 1.9 GFLOPS output to be used for other effects, and the other half for vertex output and SIMD.
Xbox
1. A hardware higher order surface tessellator is included on the NV2A, Bezier, B-spline, and Catmull-Rom spline surfaces are supported. The vertex shaders and standard T&L pipeline can operate on the vertices ouputed by the hardware surface tessellator, but not on the surface control points.
2. The CPU can send static vertex meshes to the vertex shader or standard T&L pipelines to be processed along with the tessellated dynamic geometry, or no dynamic geometry could be used at all.
http://www.cs.uct.ac.za/Research/CVC/Reading/ARCHIVE/INTEREST/VertexShaders/GeForce3_FAQ.pdf
http://www.shaderx.com/direct3d.net/tutorials/shader/shader1.html
http://developer.nvidia.com/docs/IO/1271/ATT/GF3ArchitectureOverview.pdf
PS2
1. Dynamic surface generation is supported, Sony says the GS can output 16 million triangles using bezier curves, supported on the EE.
2. Static vertex meshes must be created on the Emotion Engine and sent over to the GS, which unfortunately, does not support hardware vertex compression*. VU1, the primary vertex renderer, can output:
1,200,000,000 FMACS / 34 (vertex operation and transform & lighting)/ 2.1 = 16.8 Million polygons per second. Regardless of what the EE can put out, it will be limited to 37 Million polygons/second that the preprocessor on the GS can render with multi-texturing and gouroud shading enabled.
http://home.earthlink.net/~mmchow/
Mike Chow provides interesting methods for programming the PS2 hardware.
Texturing
Gamecube
1. No hardware 3D texturing supported.
2. The "Flipper" has a 648 Megatexel fillrate, built on Virtual texturing, automatically scaling, downsampling, and cutting off invisible textures(Hidden texel removal) from the A-RAM (80 MB/s, probably 30 ns) to the main memory (2.6 GB/s 10 NS), and from the main memory to the texture cache (10.4 GB/s 6.2 NS). The 1 MB texture cache yields 10.4 GB/s bandwidth, and 1 MB of Frame Buffer (6.2 ns sustainable latency) yields 7.6 GB/s bandwidth. The setup is very efficient for multi-texturing, as all the rendering takes place on the 1 MB of texture. The extremely low latency 1T-SRAM main memory ensures that the texture memory will remain fed at all times.
The 10.4 GB/s texturing bandwidth (32 independent macros, 32 simulataneous accesses) is suited for multi-texturing, and the frame buffer is suited for alpha blending(multi-texturing). Anti-aliasing and texture filtering is done to the main memory.
The 4 texel pipelines can render 648 M/Texels per second. (look for a further update to finish this off)
Xbox
1. Cubemap texturing is hardware supported, with no additional overhead over 1D or 2D textures. 1-2 textures run at full fill rate, and 3-4 textures run at half.
2. Pixel shaders add flexibility and multitexturing-like effects. 1-2 color blending operations run at full pixel fill rate, with 3-4 running at 50% fill rate.
http://www.cs.uct.ac.za/Research/CVC/Reading/ARCHIVE/INTEREST/VertexShaders/GeForce3_FAQ.pdf
PS2
1. No hardware 3D 2D textures supported.
2. 16 pixel pipelines and 16 texel pipelines can process 8 pixels/texels with texture mapping, alpha blending, z-buffering enabled, and 32 bit pixels used. That leads to a 1.2 Gtexel and Gpixel fillrate.
The PS2 Graphics synthesizer uses two drawing context environments, implemented on certain key drawing environment registers. The result is that the penalty for rendering two polygons with 1 different texture (or 1 with 2 different textures) on each is almost the same as it is for rendering 1 polygon with 1 texture.
Using the dual ported memory system on the GS, the read and write speeds to the frame page buffer to the GS rendering core (RGBA and Z buffer) are 19.2 GB/s each, and the read speed from the texture page buffer to the rendering core is 9.6 GB/s. The transfer speed between the two page buffers are 1.2 GB/s. Each page buffer is 8 KB in size. The bandwidth between the local memory (4 MB) and the page buffers is 153.6 GB/s. Judging from block diagrams, the PS2 does not have to process the geometry again for multitexturing.
The texture fillrates and alpha blending abilities are phenomenal, but the 1.2 GB/s bus is not.
37 Million polygon/second with 2.1 vertices per polygon (and 16 byte vertices) brings total bandwidth requirement to exactly 1.2 GB/s. 8x8 texel samples must be used when trillinear filtering.
8x8 * 32 / 8 = 256 bytes per 8x8 texture equals 7812 textures capable of being kept in the 2 MB of RAM, more then enough memory for 4-5 textures for multi-texturing. |
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| | Replies to Mister101 | | Author | Message | | | September 12, 2002 - 11:08:03pm CST |
| Xbox uses a modified PIII. :)
Welcome to the forum. |
| | | September 12, 2002 - 11:08:14pm CST |
| | You conveniently forgot to cover the graphics portion that is very important in this argument. :) |
| | | September 12, 2002 - 11:41:38pm CST (edit: 9/14/02 - 3:01am) |
| Welcome to the forum, Mister. Which part of your comparison is genuine? On average, each sentence has an error, but I'll just comment on the first part (Xbox CPU).
1) Xbox CPU is 733MHz, not 700MHz.
2) Xbox CPU has 8 logical general-purpose registers, but it has more physical general purpose registers combined with register renaming. Software only "sees" 8 GP registers, but the hardware has more that are "hidden" from software.
3) Xbox CPU features MMX and SSE.
4) SSE Unit: 733MHz * 4 FP Ops = 2.93 GFLOPS.
5) 3DNow! is slightly inferior to SSE.
Are you a PlayStation fan, a Nintendo fan, or a Microsoft hater? |
| | | September 13, 2002 - 12:16:24am CST |
| If this is your first post, I can predict what's coming!!!
Do you work for Sony or for Nintendo.
We need to go to real facts and right now xbox has the best graphics and sound out there.
A developer today can't spend three years making a game. Beacause it will not be rentable. I think that they are never going to puch probably those interiors power that you said about PS2. Because PS3 and Xbox 2 are around the corner, Just two years more.
Un saludo amigo. |
| | | October 8, 2002 - 4:51:35pm CST (edit: 10/8/02 - 4:53pm) |
| | You have so many flaws in your argument that your statement that Gameubce outperforms the Xbox is wrong but your probably too stupid to know your flaws. (shoots kyptonite bullet at Superman) |
| | | November 5, 2002 - 12:05:37am CST (edit: 11/5/02 - 5:17am) |
| I happened to have browsed the first page and noticed you edited with more errors. I'll point out these few, but there are others, of course. :)
XCPU ... The Dhrystone Mips performance hovers around the 1100 mark.
If one looks at Sandra ALU benchmarks, one may notice that a Pentium III 733MHz gets around 2000 Dhrystone MIPS.
Check this listing of benchmarks:
http://www.pooterland.com/benchmarks.html
Celeron 735MHz = 2031 MDIPS (Million Dhrystone IPS)
And another source:
http://www.thewarfields.com/BorgBenchmarks.htm
Pentium III 733MHz = 1961 Dhrystone MIPS
The Gekko CPU in the Gamecube runs at 485 mhz. It has 2 64-bit FPUs, each one capable of 4-32 bit FPs per cycle.
The only source you provided on Gekko showed that Gekko has one 64-bit FPU, no? However, you keep repeating that it has two. Got a source that confirms Gekko to have two 64-bit FPUs?
Here is that source showing one FPU (Floating-Point) and two FXU (Integer):
http://www.hotchips.org/pubs/HC01/06ibm-gekko.pdf
Also, 2-units x 4-ops x 485MHz = 3.88 GFLOPS. That's twice what Gekko supposedly can do. To bring that down to 1.94 GLFOPS, either the number-of-units = 1 or the ops-per-unit = 2.
Gamecube ... The 10.4 GB/s of texture read/write memory bandwidth is ideally suited for multi-texturing.
Are you sure Flipper can write textures at that bandwidth? Got a source to confirm? Can Flipper generate textures at all? Might be good to have some facts, yes? |
| | | November 5, 2002 - 1:36:02am CST (edit: 11/5/02 - 2:02am) |
| Oh, forgot to point out one other interesting section.
Emotion Engine ... The Dhrystone rating is 500 which is not very impressive, but the data precision which it uses is.
Of course, this "precision" you refer to must be regarding 128-bit integers. Now come the latest test questions. Excited?
1) Does a 64-bit (DP) floating-point number have greater precision than a 32-bit (SP) floating-point number? What is the precision of each?
2) Does a 64-bit integer have greater precision than a 32-bit integer? What is the precision of each? |
| | | November 25, 2002 - 8:36:33pm CST (edit: 11/26/02 - 12:36am) |
| New update, eh?
Just gonna say two things on that:
1) Cubemaps are 2D textures. Volume-Maps are 3D.
2) Virtual Texturing is not Hidden Surface Removal; VT is only HTR (Hidden Texel Removal). HSR involves triangles. Anyhow, Flipper does have HSR also, and I see it called Early-Z.
And next, to learn more about vertices, you should try out the test questions from this post:
http://forum.pcvsconsole.com/viewpost.php?pid=54837 |
| | | January 28, 2003 - 7:28:26am CST |
| | help me i heard that ps2 uses path 3 texture upload is it a load of shit or is it true. if it is true can u tell me what the hell it is |
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