Is the Wii capable of extensive AA?
- Thread starter Flux
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jandlecack
Banned
Well for one thing, unless you're playing on a 1080p set (maybe 720p set although Component + 480p helps), you won't notice jaggies as much since it's not as high in resolution. At least during gameplay.
On the other hand, I think a graphics chip more powerful than that of the Xbox 1, for SD resolutions, should be capable of producing decent enough AA.
But on the third hand, caps like these make me wonder.
On the other hand, I think a graphics chip more powerful than that of the Xbox 1, for SD resolutions, should be capable of producing decent enough AA.
But on the third hand, caps like these make me wonder.
tongue_of_colicab
Veteran
On a little sidenote, please remember that for some reason nintendo doesnt know how to make a decent screenshot. Wii (and DS) screenshots always look terribly awfull while its not nearly as bad once you see it in motion.
jandlecack
Banned
I was thinking that. "It didn't look that bad when I played it some time ago" 
DeadlyNinja
Veteran
Nintendo likes to stretch their screens for no reason. I don't know what's their problem with leaving it at 640 x 480.
The notion of whether or not he will notice is far removed from the technical aspects the OP is attempting to discuss.
That would be one reason, short of implementing a software solution. I don't think it is known sans NDA whether Hollywood even has good support for MSAA to begin with (sample rate, samples per cycle...). But at such a low rendering resolution, 2xMSAA would be pointless due to the fewer possible number of steps and the simplistic sample pattern. If by "extensive AA" you meant at least 4xMSAA, then probably not likely; that is >4x the framebuffer memory, the Z/AA sample rate/bandwidth required, etc...
Mind you, there are probably other areas of the chip that would have been more trivial to improve that wasn't such as the 24-bit bpp limitation...
edit: As only 2MB of the 3MB eSRAM are for framebuffer, you'd need 4+ tiles to even consider 640x480 w/4xMSAA (24bpp +Z24). Also, the bandwidth is pegged at around 7.6GB/s for the GCN eSRAM. A 50% memory clock increase is pitiful next to the 4x increase required... And that's not to mention any other penalties from the tiling itself...
I asked ERP about this a while ago. Since the Wii is basically an overclocked Gamecube, I think his answer is relevant. He said you either halve the vertical resolution, or you have to tile (but unlike Dreamcast and X360, there's no hardware to do this for you). For interlaced games, it had a very nice deflicker filter, but that doesn't apply in progressive scan. A number of Cube games were significantly grainier with the component cables.
Does it even support MSAA at all? I think my guess would be that it wouldn't...from what I gather Flipper/Hollywood's feature set is pretty much in line with DX7 PC parts, and none of those had MSAA (AFAIK). The first GPU I know of that had MSAA was NV20/NV2A.
There are two realistic ways to do any kind of usable ingame AA on Wii.
One is the old multiple-render thing, where you render the scene nudged half a pixel around the axis of the vanishing point in two, four or more directions and then alphablend.
This method has the advantage of being highly adaptable and scaleable. If the one scene is more complex than another, and the renderer can see it won't have time for the multible renderings of the whole scene, only the objects in most need of AA, according to a predefined prioritization list, will get the treatment.
Another method is finding the edges by using the z-buffer. It can be done rather simply by just making a copy of the z-buffer inverting it and then either "push" it around to find horizontal and vertical edges, or simply slightly enlarging and shrinking the two buffers to find all the edges at once (but without knowledge about what is horizontal or vertical). This mask can then be used as a blur mask, to only soften/AA edges with bilinear.
One is the old multiple-render thing, where you render the scene nudged half a pixel around the axis of the vanishing point in two, four or more directions and then alphablend.
This method has the advantage of being highly adaptable and scaleable. If the one scene is more complex than another, and the renderer can see it won't have time for the multible renderings of the whole scene, only the objects in most need of AA, according to a predefined prioritization list, will get the treatment.
Another method is finding the edges by using the z-buffer. It can be done rather simply by just making a copy of the z-buffer inverting it and then either "push" it around to find horizontal and vertical edges, or simply slightly enlarging and shrinking the two buffers to find all the edges at once (but without knowledge about what is horizontal or vertical). This mask can then be used as a blur mask, to only soften/AA edges with bilinear.
Wind Waker had a depth of field effect, which is responsible for what you're describing.
DeadlyNinja
Veteran
Wait, was the N64 built with hardware support for AA? I know they made quite a big deal out of it back in the day, but it wasn't used in that many games. Does the N64 have hardware support for AA, but not the GC/Wii?
The N64 used edge AA which is basically that blurring effect using the Z-buffer that Squeak talked about.
No it wasn't. The N64 relied on sorting of the polys and then doing some intelligent alphablending of the edges while rendering. As such it was much closer to "real" AA. That method just isn't feasible with the polygon counts of today though.
The method I suggested is strictly post rendering. It doesn't "know" about polygons or edges, only contrast (in the z-buffer). It's not perfect by any means but used with moderation it actually works pretty well.
You can easily do it yourself in photoshop, if you can find a pic of an aliased render with z-buffer pic too.
DeadlyNinja
Veteran
Is what you're describing what I'm thinking?
You see, I've recently did some thinking about how AA works (not on a technological level) and after viewing some games, I thought full screen isn't really necessary.
You see, while I was playing Crysis on my PC without any AA (I mean, who does?) and I never notice the aliasing. At least not when I'm in a wide open area. But whenever I enter into an enclosed space like the shacks, the aliasing is especially horrible. After paying attention to a few Wii games, I notice the same issue. It seems that if they can get AA to work on the objects closest to you, it would probably be less stressful on the hardware vs the whole screen. Whether that's actually possible is another matter.
You're saying even the PS3 and 360 can't handle it?
I'm saying it would be prohibitively expensive to sort all the polygons in a typical scene of today.
PS2 had the same "sort'n AA" type of AA build into the GS but as it would require the EE to sort all the polys of the object or scene, it would take to much power/time from elsewere. It was and is possible to do it with simple objects, screenoverlays and billboard polys.
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