Emulator

Gotta talk to NV about it, per pixel depth is a bit more aggressive in the depth calculations than it probably needs to be. Unless ztextures are used, depth calculations should be safe to be calculated in the vertex shader. Depends on why the option was introduced in the first place, possibly just as a hack for issues that are merged in the tev-fixes branch.

I thought it was added mostly as an optimization. Maybe Rodolfo knows?

Per pixel depth was added after per vertex depth, so it definitely wasn't an optimization. IIRC it was supposed to fix the pink water highlights in WW (cf. issue 3313), but it never actually fixed it.
However, it's fixed in tev-fixes. That's why I wonder if there are any games left that actually benefit from forcing per pixel depth calculations.

Forcing per pixel depth was a try to fix some problems but i think they
where fixed later by other changes. To see if is stiil needed all the games
that uses z textures must be tested, for example resident evil series or
baten kaitos game.
the performance drop in nvidia cards is previsible beacuse nvidia is known
to be dependant on early z culling to discard pixels and with per pixel
depth enable this optimization is not aplicable.

I can confirm that enabling per pixel depth in 3.5-145 causes most games to fall to the same speeds I get with newer revisions. It's great to finally know why this is happening.

In 7adb74143e4f5beb3c9d1f37d81769ecef765f02 per pixel depth isn't forced any more. But it's only tested on OGL backend and based on GLSL-master branch. Does this commit speed up rendering again?

(download link: http://dl.dolphin-emu.org/builds/dolphin-depth_texture_fix-3.5-741-x64.7z )

I broke DX9. Should be fixed in the next commit:

http://dl.dolphin-emu.org/builds/dolphin-depth_texture_fix-3.5-742-x64.7z

Seems fine speed wise (similar speed to before per pixel depth was enabled by default) and without issues (i haven't got texture flickering in wind waker).

The 3.5-741 build above restored the speeds to usual (pre-3.5-146)for me as well. I tested games on D3D9,D3D11 and OGL and saw similar results to 3.5-145 with per pixel depth disabled.

The speeds aren't quite as fast as 3.5-145 but they're only a few fps off, well within the range of normal fluctuations expected from different revs as opposed to the 50% drops I was seeing. I can post more in depth speed comparisons if I get time.

So, rebased the commit to master and commit there: http://code.google.com/p/dolphin-emu/source/detail?r=642eab92bc8ceb86f5306e26bc3374e464a1ef55

So performance issues should be fixed. Can you please verify the fix?

Windows Binary is here: http://dl.dolphin-emu.org/builds/dolphin-depth_texture_fix-3.5-549-x64.7z

Based on my tests, yes, the performance issues are fixed, but I really only have one game to confirm it.

Metroid Other M and Skyward Sword were the only two I tested that were significantly impacted by enabling PPD, and Skyward Sword would not maintain a connection to my remote long enough to see the title screen. Other M is definitely back up to full speed, at least.

I'll try to find other games that are impacted by PPD being enabled and test them later. I've attached a txt of the speeds I recorded at loading points where the fps were stable in a few games. This compares the speeds of 3.5-549, 3.5-145, and 3.5-145 with PPD enabled.

Not that it's necessary now, but Metroid Corruption also corroborated the fix.

3.5-549: 108fps 108vps 216%

3.5-145 (PPD OFF): 107fps 107vps 214%

3.5-145(PPD ON): 78fps 78vps 156%