How does trilinear filtering effect the NV2A/NV20 hardware?

[BenSkywalker]

Legion-

can some one then please provide with the theoretical maximums?

Single texture layer/ Two/ Three/ Four/ Five/ Six/ Seven/ Eight-

XBox- 932MPixels/ 932Mp/ 466Mp/ 466Mp/ 311Mp/ 311Mp/ 233Mp/ 233Mp

PS2- 1,200MPixels/ 600Mp/ 400Mp/ 300Mp/ 240Mp/ 200Mp/ 171Mp/ 150Mp

GC- 648MPixels/ 324Mp/ 216Mp/ 162Mp/ 130Mp/ 108Mp/ 93Mp/ 81MP

Certain effects will take a differing numbers of passes dependant on the hardware(as a generalized example, the XBox can do Dot3 in a single pass while the PS2 needs two), XBox overall can do the most in a single pass while the PS2 can do the least. Also, the above are Pixel rates, not Texel(and purely theoretical).

Edit- Screwed up recalling the GS clock rate

 

[Tagrineth]

Certain effects will take a differing numbers of passes dependant on the hardware(as a generalized example, the XBox can do Dot3 in a single pass while the PS2 needs two), XBox overall can do the most in a single pass while the PS2 can do the least. Also, the above are Pixel rates, not Texel(and purely theoretical).

WRONG! Flipper can do the most in one pass. It can do all eight layers, XGPU maxes at four.

Also PS2's GS is double fast (2.4Gp/s) when not texturing.

 

[BenSkywalker]

WRONG! Flipper can do the most in one pass. It can do all eight layers, XGPU maxes at four.

Utilizing pixel shaders the XGPU can do more then the Flipper can per layer is what I meant to say although it wouldn't surprise me if that carried over to absolutes as well. What takes Flipper six passes to do may take the XGPU four.

 

[Tagrineth]

WRONG! Flipper can do the most in one pass. It can do all eight layers, XGPU maxes at four.

Utilizing pixel shaders the XGPU can do more then the Flipper can per layer is what I meant to say although it wouldn't surprise me if that carried over to absolutes as well. What takes Flipper six passes to do may take the XGPU four.

Actually I'm pretty sure ERP said the TEV can interleave combines within a pass whereas XGPU can't, so that just went out the window

 

[BenSkywalker]

ERP

The major difference is that NV2A does all of it's texture reads first, so you can't do a deffered read based on a calculated result (unless it's one of the calculations supported by the texture stage) without resorting to multipass.
In the TEV texture fetches are interleaved with the combiner operations(though not totally freely), so you can theoretically do arbitrary deffered lookups.
However, in most ways flippers texture lookups are more limited as are it's combiners flexibility.

 

[Tagrineth]

ERP

The major difference is that NV2A does all of it's texture reads first, so you can't do a deffered read based on a calculated result (unless it's one of the calculations supported by the texture stage) without resorting to multipass.
In the TEV texture fetches are interleaved with the combiner operations(though not totally freely), so you can theoretically do arbitrary deffered lookups.
However, in most ways flippers texture lookups are more limited as are it's combiners flexibility.

Yeah, so? That doesn't talk about most things in one pass.

Sounds to me like Flipper might never need multipass for anything... except obvious stuff like stencil shadows ERP, or anyone with some dev experience, could you at least answer this? Which core tends to need multipass more often?

 

[BenSkywalker]

Yeah, so? That doesn't talk about most things in one pass.

It allows the NV2A to do more in one layer(which is what I meant to say in the first place ).

 

[Tagrineth]

Yeah, so? That doesn't talk about most things in one pass.

It allows the NV2A to do more in one layer(which is what I meant to say in the first place ).

Well of course NV2A can do the most with one layer!

But seriously, I'd like to hear from ERP on this, just how well can Flipper work within a single pass compared to NV2A? I'd imagine Flipper can do a LOT more (quantity, not necessarily quality) per pass from what's been said thus far, but I dunno really.

 

[Legion]

about virtual texturing:

Did the 3DFX chips use a form of virtual texturing?

When in virtual texturing are texture segmented? Do the texture pages actual represent texel data?

Does the xbox support methods of virtual texturing?

texturing:

How many clock cycles does it take to read and write from ram with the xbox.

How does ram latency effect texture read writes?

what is are loopbacks and passes? Is a pass just the some number of clock cycles it takes to do something theoretically?

 

[Simon F]

(as a generalized example, the XBox can do Dot3 in a single pass while the PS2 needs two)

That doesn't sound right. Sony's own article on doing dotprod bump mapping on PS2 had about 6-8 passes! (I can't recall the exact figure)

 

[BenSkywalker]

That doesn't sound right. Sony's own article on doing dotprod bump mapping on PS2 had about 6-8 passes!

We had a discussion about this a while ago and Faf put forth how it was possible in two passes, IIRC the were a few people who explained how it could be done in five passes or less.

 

[PC-Engine]

I think it was only in theory and not in practice, otherwise common sense would tell us that there would be games using it. It's just like the great JPEG compression argument against S3TC which is possible in theory but not in practice. Heck PS2 can do RAY TRACING in theory

 

[jvd]

how does the dreamcast fit into that graph ?

 

[BenSkywalker]

I think it was only in theory and not in practice, otherwise common sense would tell us that there would be games using it.

Why do you think that? How many GC games support Dot3 despite being very easy to implement? Taking two passes and relying on the VUs for calcs isn't like it is a 'free' feature. Apply a base map and a Dot3(with nothing else) and you are looking at three passes and a spike in the T&L calcs that are on the VU compared to native support on the Cube or even the XBox for that matter(there are more games supporting Dot3 on the Box, but still not nearly all or even most).

It's just like the great JPEG compression argument against S3TC which is possible in theory but not in practice.

I don't recall Faf or Archie ever saying that that was reasonable for in game useage, while they did for Dot3.

 

[PC-Engine]

Why do you think that? How many GC games support Dot3 despite being very easy to implement? Taking two passes and relying on the VUs for calcs isn't like it is a 'free' feature. Apply a base map and a Dot3(with nothing else) and you are looking at three passes and a spike in the T&L calcs that are on the VU compared to native support on the Cube or even the XBox for that matter(there are more games supporting Dot3 on the Box, but still not nearly all or even most).

Well because there aren't any games using bumpmapping on PS2. If it only took two passes we would've seen games using it because it wouldn't be too expensive to implement. RL on GCN used bumpmapping to name one. I think developers will only use bumpmapping on GCN games if they think it would help the look of the game. All games aren't going to use it obviously.

Regarding the JPEG compression on PS2, a lot of the PS2 backers always bring it up in arguments because in theory the PS2 could do it, but we all know that it isn't being used in any PS2 games. It's only brought up to show how the PS2 is superior when compressing textures since JPEG could have 50:1 compression ratios. This didn't come from Faf, just the PS2 backers.

 

[Fafalada]

Simon,
while it's true that you touch pixels more times, you can't really count frame buffer math as 'passes'. First it's a fixed cost so it'll easily be a fraction compared to rest of rendering, and it would confuse the hell out of people around here that already have about 20 different definition of 'texture/rendering pass'.
Framebuffer math is cheap on GS - it's one of the things embeded ram is best at.

Anyway, the rendering cost per triangle is 2-4 passes depending on mesh topology and type of lights used.

PCEngine,
that particular argument was skewed out of proportion in the past by fanboys on both sides.
That aside, we've been using IPU in practice for some time now.

 

[BenSkywalker]

Well because there aren't any games using bumpmapping on PS2. If it only took two passes we would've seen games using it because it wouldn't be too expensive to implement.

Why do you think that? It is even less expensive on the GameCube, look at the "lengthy" list of titles that use it.

RL on GCN used bumpmapping to name one.

And? One launch game out of over 100 titles. It only takes a single pass on the GameCube and ~1% of games use it, while it is twice as costly on the PS2 and there should be several.....?

I think developers will only use bumpmapping on GCN games if they think it would help the look of the game.

EMBM would have made WaveRace an incredible looking title. Why wasn't it in(it is a supported feature)?

Regarding the JPEG compression on PS2, a lot of the PS2 backers

I'm talking about PS2 developers, not fans of the platform.

 

[PC-Engine]

From the top of my head I remember RE and RE0 uses it, but I'm pretty sure there are other games that use bumpmapping on GCN, I'm just too lazy to look up all the games to find out which ones supports it

Like I said in theory PS2 can do raytracing.

Regarding the IPU, I don't doubt it's being used for certain things

 

[Legion]

excuse me for interjecting but could some one answer my questions?

 

[London Geezer]

RL on GCN used bumpmapping to name one.

And? One launch game out of over 100 titles. It only takes a single pass on the GameCube and ~1% of games use it, while it is twice as costly on the PS2 and there should be several.....?

love to see clever people fighting and bitching.....