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What technically makes DS polygons unstable?

S

snapty00

Banned
I don't really understand. I do know that the DS doesn't have hardware features like anti-aliasing and texture filtering, but why do polygons themselves look a bit ragged, too? To me, they look "shakey," sort of unstable.
 
snapty00 said:
I don't really understand. I do know that the DS doesn't have hardware features like anti-aliasing and texture filtering, but why do polygons themselves look a bit ragged, too? To me, they look "shakey," sort of unstable.
Click to expand...
I dunno? It has a hardware Z-buffer (unlike PS1/Saturn) which should help prevent the shakey/swimming/tearing polygon issues those machines had.

Personally, I find everything looks pretty stable. The only real eyesore is blocky texture quality up close.
 
I haven't played a 3D DS game for a while, but it could be both the lack of filtering as well as any sort of mipmapping. So, you end up with pixelated textures that shimmer at a distance.
 
I know exactly what you are talking about. The lack of floating point precision is to blame, I think. The lack of bilinear filtering can also make things in the distance shaky, but that's a different kind of artifacting.
 
dark10x said:
I haven't played a 3D DS game for a while, but it could be both the lack of filtering as well as any sort of mipmapping. So, you end up with pixelated textures that shimmer at a distance.
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I dunno...I would think that, too, but even in untextured polygons in Super Mario 64 DS, the polygons seem unstable.
 
The polygons are drunk baseball fans that are all after a piece of Gary Sheffield.

Plus, they're REAL depressed after they got a look at Rayman DS and Star Wars: Revenge of the Sith.
 
are you back from a ban or something snappy? You're on your usual post schedule. I kinda missed you :lol
 
Marconelly said:
I know exactly what you are talking about. The lack of floating point precision is to blame, I think.
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Erm, wouldn't this be where the Z-buffer comes in?

I think Dark hit it on the head.
 
DS polygons looked a lot more stable than what I remember in most PSOne games, I only played Metroid, Mario, and Feel the Magic though.
 
jarrod said:
Erm, wouldn't this be where the Z-buffer comes in?

I think Dark hit it on the head.
Click to expand...

The z-buffer isn't magic or anything. Lack of floating point accuracy can mean visible errors in polygon position on screen or errors in values written to the z-buffer. I have no idea what kind of floating point precision the DS has, but if the 3d math is done in fixed point, that could very well explain "floaty" polys which snap to different pixels depending on the current error.
 
Naked Snake said:
DS polygons looked a lot more stable than what I remember in most PSOne games, I only played Metroid, Mario, and Feel the Magic though.
Click to expand...

You probably mean the textures jumping around? That's because the PSOne lacks perspective correction.
 
Is the DS supposed to have perspective correction on mapping? You clearly can see the mapping distorsions just like a PS1 pretty much with all DS stuff that is mapped.
 
from what I've noticed on my little DS -- it really seems that the low resolution has a huge part.

The DS screen is very crisp - so 3d game types, you can see the polygons growing and shrinking to each pixel.
 
Erm, wouldn't this be where the Z-buffer comes in?
Click to expand...
I think what Marc means is that geometry calculations are done in fixed point, which can potentially result in precision issues. Though I personally don't think that should be the reason - N64 was doing stuff in fixed point also and it's polygons were stable.

The other most common reason for polygons(not textures) to appear shaky is subpixel precision(or rather lack of thereof) in the rasterizer. But I honestly have no clue what DS rasterizer is like in that regard.

"Is the DS supposed to have perspective correction on mapping?"
Yes.
 
"A bad home life"


"I heard speculation that DS might have been abused when it was a little baby handheld."



yes. all of this together makes poor baby DS polygons very unstable and likely to puke those polygons all over its owner :)

'urp

:)
 
Fafalada said:
"Is the DS supposed to have perspective correction on mapping?"
Yes.
Click to expand...


I thought that what they call "perspective correcting" was something to prevent mapping from distorsion when at some angle. Maybe i don't know the right term for what is supposed to prevent that PS1-like warping in mappings?
 
I think what Marc means is that geometry calculations are done in fixed point, which can potentially result in precision issues. Though I personally don't think that should be the reason - N64 was doing stuff in fixed point also and it's polygons were stable.
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Yeah, that's exactly what I meant. However the N64 example was ringing in my head so that's why I only said "I think". Your explanation does sounds plausible, though.
 
I really want to see NFSU for the DS; considering they've already released the PSP version, they probably spending a bit of time tweaking the DS version so, I'd expect that to be a good gauge of how polished 3d on DS looks.

As for Ubisucks' rayman DS... well... they just well... suck. And oh yeah... Nintendo did scrimp on the 3d processing elements for DS. 2D = DS games, is just fine by me.
 
Odnetnin said:
I really want to see NFSU for the DS; considering they've already released the PSP version, they probably spending a bit of time tweaking the DS version so, I'd expect that to be a good gauge of how polished 3d on DS looks.... for first year/generation titles.
As for Ubisucks' rayman DS... well... they just well... suck. And oh yeah... Nintendo did scrimp on the 3d processing elements for DS. 2D = DS games, is just fine by me.
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Fixed. :) And it does appear to look pretty decent so far..
 
because it's a 3rd pillar.....3rd pillar translated into english means Stop Gap Measure to give the competition something to chew on while we work on the "real" stuff.

Nintendo DS...where D means DECOY (someone come up with something for the S)
 
I haven't gotten that far in Spider-man DS but the polyz there look pretty solid to me.

And isn't it running at 60 fps too? Look pretty spiffy actually.
 
jarrod said:
Erm, wouldn't this be where the Z-buffer comes in?

I think Dark hit it on the head.
Click to expand...

It is possible that the precision for vertices using Fixed-Point math is lower than with using FP32 for position: it might not be it, but it migth be it too.
 
No matter how you cut it, 3D on DS looks like ass.

Now, bring on the Saturn+ 2D shitstorms already.
 
snapty00 said:
I don't really understand. I do know that the DS doesn't have hardware features like anti-aliasing and texture filtering, but why do polygons themselves look a bit ragged, too? To me, they look "shakey," sort of unstable.
Click to expand...

Probably the same reason that the PS2 has similar problems.
 
"Are you comparing the polygon problems on DS to PS2?
I had to rub my eyes a bit."
Click to expand...

no... he's suggesting it's the same reason which is to do with problems with the accuracy of some of the mathmatical calculations...

at least, i think that is what he's saying.
 
DCharlie said:
no... he's suggesting it's the same reason which is to do with problems with the accuracy of some of the mathmatical calculations...

at least, i think that is what he's saying.
Click to expand...

He's probably never looked at MGS3 or any of the AAA Ps2 games. Such a remark to make. Maybe if he's talking about early gen PS2 games but the latter day ones are sweet
 
chespace said:
No matter how you cut it, 3D on DS looks like ass.

Now, bring on the Saturn+ 2D shitstorms already.
Click to expand...

Absolute bullshit. Super Mario 64 DS does look great on the DS. Mario Kart is the same way.
 
Are there really bad examples of this? Playing SM64DS earlier I tried to pay more attention for such a thing, but didn't really notice. Of course the textures are a bit of a mess which could give the illusion of the polygons they're on being worse than they really are... but considering the textures cause things to look like a mess anyway, and the resolution of 256x192 per screen, if I were designing the hardware I wouldn't be too worried about additional problems of polygons being slightly shaky either.

sammy said:
from what I've noticed on my little DS -- it really seems that the low resolution has a huge part.

The DS screen is very crisp - so 3d game types, you can see the polygons growing and shrinking to each pixel.
Click to expand...
Right on.
 
olimario said:
Absolute bullshit. Super Mario 64 DS does look great on the DS. Mario Kart is the same way.
Click to expand...

Mario 64 looked good in 1996. And I'd trade in higher poly models for filtered textures any day. 3D on DS looks like ass. Bring on the 2D shitstorm.
 
chespace said:
Mario 64 looked good in 1996. And I'd trade in higher poly models for filtered textures any day. 3D on DS looks like ass. Bring on the 2D shitstorm.
Click to expand...

it looks ok. I guess I have to admit some of the visual luster is definitely gone after PSP, but it's still -acceptable-. But yeah, of course, it does not hold up well at all. I agree with you, though. Let DS remain the bastion of competent 2D gaming everywhere, cause I love me some 2D gamin'.
 
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