Xbox GPU and PC-side

[DeathKnight]

I thought the geometry only had to be redrawn if more than 4 texture layers were used (I know Halo uses 4 layers with extensive bumpmapping and a lot of detail texturing.. don't know if the geometry is being drawn twice though).

 

[archie4oz]

What sort of texturing is loopback really good for? I’ve never been able to find any unbiased texts on that.

It's more about permitting you more dependent reads per-pass than anything else. What you do with it is really more of a "creative" use argument.

Besides, if anything in Xbox is lacking it's the memory. 128 would have been better.

I dream of a day when MS suddenly say, "Ummm, there's actually 128MB of ram in the machine, we will unlock it for the devleoper now, good bye!"

It'll happen the same day Sony unmaskes a register that unlocks the other 28MB of VRAM on the "incorrectly" labelled I32s in every PS2, and turns off the "slow-mode" on the EE-Core so that it suddenly has full access to that "hidden" 128KB 16-way L1...

 

[zurich]

It'll happen the same day Sony unmaskes a register that unlocks the other 28MB of VRAM on the "incorrectly" labelled I32s in every PS2, and turns off the "slow-mode" on the EE-Core so that it suddenly has full access to that "hidden" 128KB 16-way L1...

Would 128k of 16-way L1 on the EE core really be a big performance booster? What kind of code is run on the core versus the VUs that would bottleneck the system that badly?

 

[Squeak]

I thought the geometry only had to be redrawn if more than 4 texture layers were used (I know Halo uses 4 layers with extensive bumpmapping and a lot of detail texturing.. don't know if the geometry is being drawn twice though).

I don't know about "extensive bumpmapping" It's used here and there to good effect.
On average I think Halo is doing something like 2.5 passes, and most of that is base, detail-texture and sometimes some light/ shadow maps.
Having to recalculate and resend large chunks of geometry for detail texturing could be the reason for Halos relatively low polycount and 25fps. framerate.

 

[Gubbi]

I think it's more like base+detail+reflection map (environment map)+light map, so 4 for most textures.

Cheers
Gubbi

 

[Squeak]

Environment and light maps is only used on a small percentage of the of the polygons. So on average (and that's what we are talking about, right?)
I think 2.5 layers is a good guess, based on what it's possible to deduce from what you're seeing when you play.

 

[McFly]

It'll happen the same day Sony unmaskes a register that unlocks the other 28MB of VRAM on the "incorrectly" labelled I32s in every PS2, and turns off the "slow-mode" on the EE-Core so that it suddenly has full access to that "hidden" 128KB 16-way L1...

That's why Killzone looks so damn amazing. (Just joking)

Fredi

 

[embargiel]

The XGPU is also said to include a couple functionalities that were found in the much later NV30 (supposedly some special geometry features).

Was that the Allard's statement? At the time he stated that, not even an NV25 specification had been announced. I think that They thought that GF4Ti would be codenamed "NV30" instead of NV25. And actually, there's still one feature on XGPU unsupported by NV25, but present on Quadro series. It's called two sided lighting (or some people say "signed stencil buffer"). But based on somebody's experience patching GF2 to Quadro2, it's totally unlockable.