amk said:Shouldn't that be 1.0GTexels/s and 500MPixels/s?
They're quoting MegaPixels aren't they? The MBX PRO was claimed in their own link to be able to reach 750MPixels/s.
If we are both agreed that MBX is 1*1 then a 200MHz MBX would have a 500Mt/s fill rate. A 200MHz MBX Pro (1*2 or 2*1) would have a 1Gt/s fill rate, which would be OTT without something like 4+ multitexturing layers.
I'm as sure as I can be that all models have only one pipeline.
The feature-set for MBX PRO also states dual MT.
If the texel fill rate were higher than the pixel fill rate, I'd expect IMG to talk about Mt/s rather than Mp/s.
If we'd be picking needles out of straws, they shouldn't use effective fillrates either then. They didn't at least for Series3.
Are you assuming 32 texture layers? :?
32bpp.
I make it 320[x]*240[y]*30[fps]*2[MT]*3.39[overdraw] = a hilarious ~15Mtexels/s. Without the MT, an even more hilarious ~7.5Mpixels/s.
Either I've had way too little sleep, or that demo was not fill rate limited.
Or you forgot to encount colour depth maybe.
For that matter, 640[x]*480[y]*60[fps]*2[MT]*4[Kyro's overdraw estimate] = ~150Mt/s. MBX has fill rate to burn. Which is good, because trilinear filtering and y-axis FSAA both halve available fill rate, and dot3 (afaics) requires two passes. So with 4x FSAA and trilinear, we would need 600Mt/s, and more if we use dot3.
Furthermore, not using overdraw or effective fill rates and using 16x:9y :
~200Mt/s = 850[x]*480[y]*60[fps]*2[MT]*2[FSAA]*2[trilinear OR dot3]
Isn't that handy? Then we just need to ensure that %age of pixels using trilinear + %age of pixels using dot3 < 100
or
~200Mt/s = 600[x]*340[y]*60[fps]*2[MT]*2[FSAA]*2[trilinear]*2[dot3]
For dot3 - tbh I have no real idea how many clock cycles it would take.
Obviously the second pass hurts our polygon throughput.
This screenshot from the Nokia presentation is 600*450. Possibly it was cropped or resized, as the concept phone shown had a 16:9 screen.
Holy smokes what an awkward compilation....anyway MBX might be quite powerful for the PDA/mobile market, but it for sure hasn't fill-rate to spare. Fill-rate and/or bandwidth are amongst those things an accelerator can never have enough of.
I'd expect PowerVR to quote the highest figures they could. Giving performance figures for e.g. 60MHz when you've stated elsewhere the core can run at 120MHz isn't my idea of aggressive marketing.
I do expect the 1M tri/s for MBX lite is for 120MHz. And I still think its 1*0
If you manage to give me a half way reasonable explanation what on God's green earth a chip could render with 1*0, apart from Z's I'd be happy to hear it.
From www.mitrax.de:
That's on a Dell Axim X50v; I'm not sure anymore what the clockspeed of MBX in that thing is, but I doubt it's any higher than 65-70 MHz.
INTEL's 2700G comes in two flavours according to their whitepapers; 2700G3 with 384kb and 2700G5 with 705kb on-die memory. If it would have had a VGP, on-die memory would had been slightly larger since the latter gets it's own on-die memory too. Both on 130nm.
Found it:
• Up to 75 MHz 3D Graphics Core
• Deferred Texturing
• Screen Tiling
• Flat and Gouraud Shading
• Perspective Correct Texturing
• Specular Highlights
• 32-bit Z Buffer
• 32-bit ARGB Internal Rendering
• Full Tile Blend Buffer
• Z Load/Store Mode
• Per Vertex Fogging
• 16 and 32-bit RGB Textures
• YUV 4:2:2 Textures
• DirectX* Compatible 2-bit and 4-bit Runtime Texture Compression
• Point, Bilinear, Trilinear, and Anisotropic Filtering
• Dot3 Bump Mapping
• Backface Culling
• Small Object Culling
• Fixed-Point to Floating-Point Conversion
• Accelerates Rendering of Triangle Lists, Strips and Fans
• Per-Pixel Alpha Blending
• Full Scene Anti-Aliasing
• Hardware Clipping
• 1 Million Triangles/Second Rendering
Up to 75 MHz, 32-bit graphics engine
831K triangles per second (tps) processing
capability, 84M pixels per second (pps) fill rate
It says up to 75MHz; I might be wrong but I think it's clocked at 67MHz in the Dell Axim X50v.
ftp://download.intel.com/design/pca/companion/datashts/30094801.pdf
Look at it that way: there are 2.5M Tris/sec claimed for MBX and 3.0M Tris/sec for MBX PRO. Now assuming MBX is at 120MHz, what would you assume does it need to reach 3.0M Tris/sec? Something like 150MHz maybe?
200Mp/s on a mobile is starting to look generous.
At 200MHz an MBX will have quite a bit higher triangle throughput than a Dreamcast itself; factor in the VGP (4 MFLOPs/s per MHz = 4*200 = 800MFLOPs/sec) and it's VS1.1 capabilities and you're quite a bit ahead of DC.
AFAIK all above products are 1 TMU per pipe. Kyro has free trilinear, MBX free 2x FSAA. DC has neither.
KYRO didn't have free trilinear; it did have normal trilinear (2 clocks) which did cost quite a bit in performance and "fast trilinear" which worked only with texture compression enabled (16 texel fetches from a single MIPmap).
On MBX 2xMultisampling is "free"; with 2x Supersampling it'll lose half it's fillrate like any other accelerator out there. Dreamcast supported 2xSSAA if my memory shouldn't betray me.