powervr2 limits

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powervr2 limits

Post by chao2 » Thu Oct 23, 2014 11:45 pm

how come the dreamcast can only reach 3million polygons but the powervr2 limit is 7 million polygons? what causes this and is there any way to get around it?
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Re: powervr2 limits

Post by bogglez » Sat Oct 25, 2014 9:06 am

I'm not sure whether those numbers are accurate, but in general something else may be the bottleneck. Think transformation, culling, shading, texture lookups, ...
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Re: powervr2 limits

Post by BlueCrab » Sat Oct 25, 2014 9:15 am

Any benchmark numbers for the PVR would imply non-transformed, non-lit, non-textured, opaque triangles. In other words, not what you'd actually use to make a real game.
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Re: powervr2 limits

Post by chao2 » Sat Oct 25, 2014 10:47 pm

Wow thanks for your answers. Now here is another question. In shenmue 1 and 2 I notice a lot of the characters look very blocky even Ryo and these games were made in 1999. When the psp,ps2 and gamecube were released their games looked hardly blocky at all.The difference between them and the dreamcast seemed pretty small but got bigger when the dreamcast was discontinued. Was the pvr already being pushed in 1999 and dreamcast couldn't compete visually any more with the ps2 and gamecube or was there more things the pvr could do to appear to make games appear less distinguishable from the ps2 and gamecube?
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Re: powervr2 limits

Post by bogglez » Sun Oct 26, 2014 12:35 pm

Maybe that's because of the port from the Saturn.. I think the meshes in Dead or Alive 2 look better for example. I don't believe the Dreamcast was pushed after such a short run. The Playstation 2 Developers had many more generations of games.
I saw a presentation by the developer house Naughty Dog which made the Uncharted series. They also showed how much better they got with each game on the same console.
There are also manuals by Sony for developers which show in hindsight how difficult it was to program for the PS2, since the developers changed the way they wrote their engines quite dramatically.
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Re: powervr2 limits

Post by cube_b3 » Sun Oct 26, 2014 1:27 pm

We've had these discussions before... If you have a look at the cancelled games that were intended for DC such as Virtua Fighter 4 that graphics were supposed to get much better. We really had no time for developers to find creative ways to push the DC's limit.
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Re: powervr2 limits

Post by bogglez » Sun Oct 26, 2014 4:06 pm

cube_b3 wrote:If you have a look at the cancelled games that were intended for DC such as Virtua Fighter 4 that graphics were supposed to get much better.
Virtua Fighter 4 was just developed for the Naomi though I think, which has much more horsepower than the DC?
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Re: powervr2 limits

Post by chao2 » Sun Oct 26, 2014 6:05 pm

bogglez wrote:
cube_b3 wrote:If you have a look at the cancelled games that were intended for DC such as Virtua Fighter 4 that graphics were supposed to get much better.
Virtua Fighter 4 was just developed for the Naomi though I think, which has much more horsepower than the DC?
Virtua fighter 4 was on the Naomi 2 which was two naomi boards stacked together.
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Re: powervr2 limits

Post by chao2 » Sat Nov 01, 2014 1:47 pm

Can the pvr make characters appear less blocky using less polygon since it doesn't have a lot ? Is there a way to do this using tricks or is this is impossible?
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Re: powervr2 limits

Post by bogglez » Sat Nov 01, 2014 3:08 pm

The PVR in particular can only help with that using Gouraud shading, bump maps and texture compression. Bump maps can make planes look as if they had 3D detail. In general good texture work becomes more important than before. You could also perform ray tracing in software to get perfectly round shapes.

This is low poly but has great textures:
Image

There are also a lot of perceptual tricks in play. Humans are not very good at judging what looks real and what does not.

But instead of trying to get around that limitation, what about actively embracing it in your design? There are quite beautiful blocky art styles. Because the viewer realizes the blockiness is on purpose, he won't perceive it as something negative.

Image
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Re: powervr2 limits

Post by chao2 » Sat Nov 01, 2014 9:04 pm

So instead of using extra polygons it would be better to use textures,bump mapping, and gouraud shading to make characters appear less blocky. But if that was done on a game would it make it less distinguishable from a ps2 or gamecube version of the same game? Would this be easier doing in Virtua fighter 4 for dreamcast rather than a rpg like kingdom hearts 2.
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Re: powervr2 limits

Post by bogglez » Sun Nov 02, 2014 5:31 am

I think you should find a good balance.

In general the fill rate is not a problem on the DC, but memory consumption for geometry is. Fill rate is a problem on the GCN and PS2 because they use rasterizer graphic pipelines, unlike the DC which uses a deferred tiled renderer (a raycaster), but they have much less of a storage problem for geometry due to more RAM. Transparent polygons on the DC are also cheaper than on the GCN/PS2.

Another reason why you might not push as many polygons on the DC in practice is that transforming and clipping geometry causes CPU overhead, while the GCN's GPU for example can take care of that due to T&L support. The DC CPU has some nice instructions for matrix math, but having a completely different processor work on that data in parallel is very beneficial.
The PS2 is a floating point math monster, but in practice it's quite difficult to get maximum performance out of it. Even AAA developers back then had serious issues getting even half the performance out of it (check out the Sony and Naughty Dog slides I mentioned before). It's much easier to get good performance out of the DC and GCN.

A game like Virtua Fighter 4 is very different to an open world RPG like Kingdom Hearts. You have very few meshes to store (2 high poly characters + relatively low poly background), you want high quality textures and don't need to swap stuff in and out of memory during runtime. This works well on the DC.

Now Kingdom Hearts doesn't look very "open world" to me (doesn't seem to load resources in the background etc), but in general you'd need a higher amount of RAM compared to the other game type to make swapping techniques work well enough (to have a buffer for reading from disc).
I think a bigger issue for KH2 on the DC would be disc storage space. GD-Roms only store about 1GB, DVDs about 4.7gb. That means you wouldn't be able to have as many prerendered cutscenes as in FFX. Disc reading speed is also important, which is probably higher on the PS2, but I'm not sure.
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Re: powervr2 limits

Post by chao2 » Sun Nov 02, 2014 11:21 pm

So I assume the dreamcast would look barely decent in a right taking in all this account only if the ps2 and gamecube have maximum performance or would look nearly the same? would the dreamcast version with fewer cutscenes be comparable




same with this one

It may seem like Im asking the same question but Im a newbie with no programming knowledge and Im hoping someday maybe however long it takes one or more game from the ps2 and gamecube could be ported to dreamcast without too much sacrifices.
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Re: powervr2 limits

Post by chao2 » Sun Nov 02, 2014 11:25 pm

ImageGod of war





Resident evil 4Image


Do you think dreamcast version of these games would look similar taking into account less cutscenes and disc space? would Leon kennedy and Kratos look like ryo from shenmue in terms of graphics right or better?


Or would they look like psp games on a larger screen?
Last edited by chao2 on Mon Nov 03, 2014 1:16 pm, edited 1 time in total.
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Re: powervr2 limits

Post by bogglez » Mon Nov 03, 2014 4:20 am

chao2 wrote:So I assume the dreamcast would look barely decent in a right taking in all this account only if the ps2 and gamecube have maximum performance or would look nearly the same?
If you're going for realistic graphics and assume perfect utilization of the hardware (which usually only happens for console exclusive titles made by very competent programmers), then the GCN and PS2 will beat the DC hands down, I think.
chao2 wrote:would the dreamcast version with fewer cutscenes be comparable
You could have prerendered cutscenes (we're talking 640x480 resolution or lower here..), but not as many. One could easily get around this by not using pre-rendered cutscenes, but scripted ones instead. In FF13 for example they used scripted cutscenes because they didn't like the disconnect of ingame graphics and CG graphics, so they have their upsides too.
chao2 wrote: It may seem like Im asking the same question but Im a newbie with no programming knowledge and Im hoping someday maybe however long it takes one or more game from the ps2 and gamecube could be ported to dreamcast without too much sacrifices.
I don't know why you'd want that. It'd be a fun challenge, but we don't even have access to the source code.
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Re: powervr2 limits

Post by chao2 » Mon Nov 03, 2014 1:18 pm

I had to re edit my last post
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Re: powervr2 limits

Post by chao2 » Tue Nov 04, 2014 6:26 pm

How would you think God of war and Resident evil 4 would look on the dreamcast compared to their original consoles?
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Re: powervr2 limits

Post by chao2 » Sat Nov 22, 2014 10:11 pm

Can the pvr emulate psp games ?
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Re: powervr2 limits

Post by RyoDC » Sat Nov 29, 2014 8:07 am

chao2 wrote:Can the pvr emulate psp games ?
If we want to keep answer simple, no, it's not.
Pvr2 alone can not emulate psp games, it requires all hardware to cooperate in a maximum efficient manner.
Also, I even doubt that DC will be able to emulate PSP games at fullspeed (considering PSP is more "powerful" then Dreamcast in core aspects).
How do I try to build a Dreamcast toolchain:
Image
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Re: powervr2 limits

Post by chao2 » Sat Nov 29, 2014 11:00 pm

So it is still possible for a dreamcast to emulate a psp or no?
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