Ppsspp: Tekken 6 (ULUS10466): Fighters' legs tremble/shudder/"flicker" in battle

[thedax]

I'm surprised nobody has reported this yet, but it's been afflicting this game since at least June or July of 2013, so a precise range of builds is not really possible. I haven't seen reports of this happening before then, however. @solarmystic: do you know if this problem existed back in the 0.7 or 0.7.5 days, or even earlier?

Basically what happens is both fighters' legs will move back and forth on their own in a glitchy manner when they're idle, and not being moved by the player/AI. It's especially noticable if one goes into practice mode and pushes the opponent up against the wall.

Steps for reproduction:

1. Start Tekken 6.
2. Enter practice mode.
3. Pick any two characters, and push the CPU opponent against the wall.
4. Observe the trembling/twitching/"flickering".

I tested with 0.9.6-881-g8c63f38, Windows x64. No combination of Vertex Caching, HW transform, texture scaling, buffered/unbuffered rendering, Jit on/off, Fast Memory on/off, SoftGPU, etc., fixes it.

What should I look for in the GE Debugger?

SoftGPU testing isn't an option; the game is completely broken graphically in it:

Here's a video of the problem:
https://drive.google.com/file/d/0BwcSjM-JLvbkX2VKM1NhOTVtQmc/edit?usp=sharing

[solarmystic]

@thedax
I only really got into the project from 0.7.6 onwards (end of April 2013) and back then I think the game had already exhibited the aforementioned issue. My initial impressions of the game on the emulator using 0.7.6 in the forum thread are here:-

http://forums.ppsspp.org/showthread.php?tid=1274&pid=19061#pid19061

Of course it was considered very minor as compared to the inability to save your game back then, and not to mention the pretty heavy requirements of the game before Software Skinning and the Texture Coord Speedhack was introduced much later.

[thedax]

I guess it's safe to assume it's always been a problem then, for as long as the game has worked. Thanks for replying.

[unknownbrackets]

I wonder if this could actually be a cpu bug. Does it happen with interpreter?

-[Unknown]

[thedax]

Yes. It happens regardless of Fast Memory, Vertex Cache, JIT on/off, etc.. I cannot find a setting which makes it better or worse.

[hrydgard]

This has been the case since the game started working, so it has probably never been correct. I believe it to be some sort of CPU issue, possibly float16->float32 conversion or the inverse as the game uses those quite a lot but I'm really not sure.

[brujo5]

no much problems on iphone 5S

[IntendedConsequence]

Any progress on this one? Those flickering legs are very distracting.

[hrydgard]

It's a very difficult issue to debug, and I guess there's not enough interest as the game is still very playable. It will probably be figured out someday though...

Does JPCSP have the same problem, by the way?

[IntendedConsequence]

JPCSP has the same problem.

[unknownbrackets]

In the GE debugger, what vertex type is it using when drawing the legs?

It's possible this may have been improved by the vrot fix.

-[Unknown]

[thedax]

It's still happening at about the same frequency as I remember.

It uses u8 texcoords, s8 normals, s16 positions, u8 weights (2).

Dump from all of the tabs: https://gist.githubusercontent.com/thedax/a86dc83f968206bfd995/raw/1d9653189fb3e1321e02938816d81c29ee73d64b/gistfile1.txt

Screenshot of when I took it (I don't know if this frame is a trembling frame or not):

[unknownbrackets]

Hmm, it's using normal projection:

gen: tex matrix, proj: normal

And the normal is s8.

-[Unknown]

[unknownbrackets]

Did the position scale thing help this, maybe?

-[Unknown]

[daniel229]

Still flickering

[thedax]

No change here either. The saga continues.

[justm34evah]

Any news, updates? The problem is rather annoying and new builds haven't fixed it. Maybe we should report it somewhere else. Do you have any ideas?

[hrydgard]

No news because no more clues to what the problem might be have been found.

[justm34evah]

That was fast! All I can tell you is that the problem has to do with the walls of a stage. For example, if a stage has walls the problem seems to occur less, if a stage doesn't have walls (go into training mode and select wall off) the problem seems to be more visible. Also, when my character stays on a breakable floor the problem also persists.

[justm34evah]

Thank you for your reply! BTW. I hope this will be fixed soon! I super love Tekken 6!!!

[ALOIYD]

This bug is too funny, especially when fighting Azazel, pls fix, Cannot survive more.

[justm34evah]

hrydgard I didn't actually realize you were the owner of this emulator project. I want to thank you for your hard work from the bottom of my heart! PPSSPP is a great improvement over JPCSP (tested them both) and only on PPSSPP I had a great gaming experience. I enjoyed playing Blazblue Continuum Shift II, Tekken 6 and Fate: Unlimited Codes. I love your work. I definitely hope for a fix of the Tekken 6 issue but hrydgard should take his time to do what is best and I am pretty sure he is trying his best to fix the issue! Maybe this year we'll play a perfect version of Tekken 6 while next year Tekken 7 arrives (on PC too!)

[issuer]

Found something interesting, this bug also happens in the Phantasy Star Portable games. In the animations "(hold)", your character's legs tremble just like in Tekken 6. I have become fond of this bug, haha.

EDIT: Nevermind, the game seems to do the same thing on a real PSP.

[VIRGINKLM]

Possibly, when there is somekind of rounding involved and then you make a conversion (float16 to float32 or float32 to float16) this makes it a bit inaccurate, hence the animations or the positions of the legs could be a bit off.

[tabnk]

Didn't realize this bug already occur more than a year ago.

[hrydgard]

@tabnk , the legs have been shaking as long as the emulator has been able to run the game. Still no idea what the cause is.

[unknownbrackets]

Do the legs jitter even slightly differently with jit on/off or respect fpu rounding on/off? Or is it the same jitter?

I wonder if this is related to the Ridge Racer, Castlevania, and Dissidia replay problems. If there were all caused by some cpu bug squirreled away somewhere...

-[Unknown]

[tabnk]

Tired Jit On and Off but no different at all.

[hrydgard]

We've been though this before, JIT has no bearing on the leg shaking. It's either a slight precision issue with some instruction, a genuine bug in the interpreter (and also JIT if the buggy instruction is jitted), or some weird timing issue causing some bone matrices to get updated at the wrong time or offset somehow.

[unknownbrackets]

Well, I know that they still jitter with jit off, was just wondering if it's even slightly differently. There are some remaining precision (and INF/NAN) differences between the interpreter and jit. If it's different, we could be mostly sure it's a cpu bug.

If bones are ignored, they don't jitter at all? Do we know it's bones?

-[Unknown]

[tabnk]

No possible fix for this ?

[hrydgard]

As has been said repeatedly, nobody has figured out how to fix it yet. Asking for it again doesn't help.

[VIRGINKLM]

Also, it could be unrelated but it's worth giving a look at it. Notice the buzzing feeling on the screen (Tekken DR), like the screen is mounted to a vibration mechanism, kinda like how PCSX2 handles interlaced output. (I try to describe the effect as accurately as I can) There is a possibility trying to understand what causes that issue would help understand what's causing the limb shaking issue.

[unknownbrackets]

IIRC, the PSP LCD screen has such a low response rate that interlacing effects aren't even visible. If the buzzing is fast enough, maybe it does actually happen on a PSP and you just can't notice? Although from the videos it doesn't seem exactly like that...

-[Unknown]

[VIRGINKLM]

I did 2 tests to be sure it's a PPSSPP issue:

1. Used component cables to connect to a TV so I can be sure that PSP's screen is not too cheap to reveal the issue (seemed OK to me).
2. Recorded footage (with PPSSPP) at PSP Native resolution of 2 fights and transfered them on PSP to play them back so I could check if the buzzing effect is visible on PSP's screen (and turns out it is visible).

So it's definitely a PPSSPP issue.

[unknownbrackets]

Okay. Is this game multiplayer? Can you record a fight where you control both players?

If it were possible to get the same exact recording (e.g. character 1 standing still, character 2 immediately moving left at full speed from start, and continuing until the time runs out, or etc.), with one reproducing the problem (PPSSPP) and the other not (PSP), or especially even two of each, then it might at least be possible to see what in the recording is incorrect. It's not certain that would lead to a fix, but it's an idea.

-[Unknown]

[justm34evah]

News regarding this issue. It seems to be related to the character's position. For example, if you choose an infinite stage, the more you move away from your starting position, the more legs will tremble/flicker. If you return to your starting position the problem barely seems noticeable. Hope it helps!

[hrydgard]

That's quite interesting, means it is probably a floating point math precision issue of some sort, as that's a typical kind of thing that can happen, as precision drops the further from the origin you are. But that kind of thing really shouldn't happen in arenas that small, heh.

[justm34evah]

It has been so long since this issue came out. No fixes as of yet? Disappointing... :( I'd love to help, but my programming skills are close to zero. Tekken 6 is my fave game on the PSP.

[justm34evah]

I've tried the latest version (1.1.1.306), the problem still occurs, but the game looks and runs great. It's kinda sad that it's the only problem...Any genius around? haha

[tabnk]

Awaiting some fix as well but not likely to happen anytime soon. Just play on REAL PSP better

[VIRGINKLM]

I wonder if a double precision hack would do anything to it, good or bad, if it does affect it in any way, not that it's the right thing to do but anyway.

[justm34evah]

Hrydgard, any opinions? Can you apply that precision hack? I want to play
the game properly and on a full screen .lol.

2015-11-18 17:49 GMT+02:00 VIRGINKLM [email protected]:

I wonder if a double precision hack would do anything to it, good or bad,
if it does affect it in any way, not that it's the right thing to do but
anyway.

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[hrydgard]

There is no "double precision hack". If I had one, I would have used it to figure out what the real problem is and fixed it. Right now I really have no idea.

[justm34evah]

Hey, hrydgard, I remember you were saying sth about a floating point math precision. Have you tried working that one out? Or...it still doesn't work. So basically, there is a starting point in a fighting arena and the further each character is from that starting point, the more visible is that leg shaking issue. It's still the same with newer builds. And I'm guessing the character's legs shake more on breakable arenas because their origin is on the ground floor...

[hrydgard]

Whatever math error this is, it may be related to the #8548 laser issue.

[justm34evah]

Great, great keep trying to find out the issue. T7 is coming soon so we
need to play T6 properly. Thank you for looking into this matter, it's been
an issue for a long time. Best luck finding the cause and solving it. Can't
wait! :)

2016-02-04 17:12 GMT+02:00 Henrik Rydgård [email protected]:

Whatever math error this is, it may be related to the #8548
https://github.com/hrydgard/ppsspp/issues/8548 laser issue.

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[ALOIYD]

...It's not fixed yet?

Meh, i'd better go Tekken 7 for now.

[hrydgard]

You can still play it, the legs just shake a little. Still mystified as to why.

[justm34evah]

We all want to play Tekken 7. Lol. Just pray it releases on PC otherwise
most of us will not be able to enjoy it. Oh well, it would be their loss. I
still hope Tekken 6 PSP will be perfectly emulated in the near future, it's
a nice game.

2016-02-07 19:30 GMT+02:00 ALOIYD [email protected]:

...It's not fixed yet?

Meh, i'd better go Tekken 7 for now.

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[RinMaru]

I love tekken its my fav fighting game along with Dead or Alive.

[justm34evah]

Tekken 7 is almost here and 6 is still has this annoying visual bug. :( No revisions seem to fix the leg shaking issue. The good thing is that Tekken 7 is coming to PCs. Cheers!

[fuhuan416]

I tested Tekken with Xenia and Cemu, the results tell me about character's datas by GPU works.

[VIRGINKLM]

I feel the result is due to somekind of rounding issue. Legs seem to shake with progressive agression depending on your distance from the middle of the stage in all 3 axes. It affects models even when they are using somekind non-battle animation such as Jin's intro cutscene in Story Mode. Like the game does it's best to reset/fix somekind of collision error.

[justm34evah]

It's quite possibly related to this, but no one seems to care about it,
it's not like Tekken 6 is not the best 3D PSP game, and PPSSPP is not the
only way we can play T6 on PC. I mean, I understand there are other issues,
but this has been on for far too long. Oh well, I give up, not that I can
do anything about it. Thank you for your hard work though, all of you, and
thanks to PPSSPP devs we can at least play T6 at perfect speed.

On Jul 25, 2016 11:10 PM, "VIRGINKLM" [email protected] wrote:

I feel the result is due to somekind of rounding issue. Legs seem to
shake with progressive agression depending on you distance from the middle
of the stage in all 3 axes. It affects models even when they are using
somekind non-battle animation such as Jin's intro cutscene in Story Mode.
Like the game does it's best to reset/fix somekind of collision error.

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[ALOIYD]

Rest in peace Tekken 6

The only PSP game that got a hilarious gamebreaking bug (trembling legs push you hard) and didn't get fixed

[justm34evah]

I fell your grief, honestly. It's like fate conspired against us, Tekken
fans. I mean, I never like thought I could actually play the game on PC
seeing how it was console exclusive for PS3 and X360, I never knew it got
released for the PSP, when I found out and remembered my cousin had a PSP,
bought it and got the game. Then I dumped it when I found out you could
actually play PSP games on PC (since the JPCSP days), the framerate was
horrible, however it got better and I eventually sold my PSP as well seeing
how I didn't use it much.

PPSSPP was like the best thing ever when it came out, awesome speed, great
configuration, mobile friendly. I tried Tekken 6 on it as soon as possible
and never noticed the leg shaking issue at first, but as I played more the
problem was more noticeable. Must I say Tekken 6 on PSP has better reviews
due to better loading times and no crappy Tekken Force like Story Mode (the
story is gonna be explained in the next game anyway, it's usually this
way). And of course, it's the best 3D fighting game on the platform. The
leg shaking issue is an annoying visual bug that takes away the whole
experience and like some users said, it's hilarious. I can't train with my
character without restarting every 2 minutes due to this issue.

2016-08-08 5:14 GMT+03:00 ALOIYD [email protected]:

Rest in peace Tekken 6

The only PSP game that got a hilarious gamebreaking bug (trembling legs
push you hard) and didn't get fixed

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[VIRGINKLM]

You are being overdramatic on an issue reporting site. Chill out and give a second to the devs. They deserve it.

[justm34evah]

They do, but it's not like 2 years were not enogh, lol. Perhaps their
priorities are elsewhere. I completed Tekken 6 it a long time ago. They did
a great job with the speed and graphics, the devs, and the emulator is one
of the greatest ever up there with Dolphin, but this leg shaking issue has
been bothering me since Tekken 6 is the only game I play using PPSSPP. :)

2016-08-20 12:51 GMT+03:00 VIRGINKLM [email protected]:

You are being overdramatic on an issue reporting site. Chill out and give
a second to the devs. They deserve it.

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[justm34evah]

Tested the game again using PPSSPP yesterday's version. No improvements
whatsoever. Is this issue so hard to fix? It would be great to make this
run perfectly before Tekken 7 hits PC in June. Honestly, the leg shaking
issue is the only issue Tekken 6 has.

2016-08-22 21:05 GMT+03:00 t0nyfightfan . [e-mail]:

They do, but it's not like 2 years were not enogh, lol. Perhaps their
priorities are elsewhere. I completed Tekken 6 it a long time ago. They did
a great job with the speed and graphics, the devs, and the emulator is one
of the greatest ever up there with Dolphin, but this leg shaking issue has
been bothering me since Tekken 6 is the only game I play using PPSSPP. :)

2016-08-20 12:51 GMT+03:00 VIRGINKLM [e-mail]:

You are being overdramatic on an issue reporting site. Chill out and give
a second to the devs. They deserve it.

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[hrydgard]

@justm34evah Yes, it's so hard to fix. At least when a game crashes, you can find out where. But figuring out exactly what is going wrong with the math anywhere in a huge game like Tekken is not fun or easy, especially since the results are _almost_ right.

If you can figure it out, well, please do so.

[justm34evah]

I'd love to, honestly, but math was never my strong point. :P Thans for
your hard work, really, and if it's so hard then I quit. Other than testing
the game, I can't do much. Perhaps RPCSP3 or Xenia will emulate it better
in the future, who knows? I have nothing left to do but hope. See ya' and
good luck improving the emulator for the other games! It's the last time I
come up with this subject, promise.

2017-01-28 23:09 GMT+02:00 Henrik Rydgård [e-mail]:

@justm34evah https://github.com/justm34evah Yes, it's so hard to fix.
At least when a game crashes, you can find out where. But figuring out
exactly what is going wrong with the math anywhere in a huge game like
Tekken is not fun or easy, especially since the results are almost
right.

If you can figure it out, well, please do so.

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[hrydgard]

Right, Xenia is probably the best hope :) This is a very unusual type of bug. We already have extensive tests of most of the PSP VFPU's built-in math functions, and we're generally very close to the hardware so how something can cause shaking this bad still baffles me.

That said, we've found and fixed very odd bugs before so maybe one day we'll fix something seemingly unrelated and suddenly the legs will stop shaking..

[paulodeleo]

As the video from the OP is long gone, I have just uploaded a high quality demo to youtube for anyone who may want to see the bug and maybe get interested in trying to fix it.

[justm34evah]

Looks like a lost cause at this point.....

On May 15, 2017 6:24 AM, "Paulo Henrique Deléo" [e-mail]
wrote:

As the video from the OP is long gone, I have just uploaded a high quality
demo to youtube https://www.youtube.com/watch?v=bXLjJAbDteI for anyone
that wants to see the bug and maybe get interested in trying to fix it.

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[hrydgard]

That post didn't add much information to the issue.

[justm34evah]

I wonder if it Tekken 6 on PPSSPP will ever be fixed and perfectly playable.....I just want this thread alive at least.....The leg shake is basically the only issue this game has.

[tabnk]

Almost 4 years :D

[VIRGINKLM]

Whatever it is, it seems to have some kind of a constant refresh rate, like every shake happens on every even frame so it's like 15 shakes per second. Dunno if that helps narrowing down the issue with the debugger.

[justm34evah]

We also know it's a proximity issue, the farther the characters get from
the initial position, the more their legs will shake. This is why it's more
noticeable on breakable ground arenas, the center of the stage is down
below I think.

On Nov 9, 2017 5:27 AM, "VIRGINKLM" [e-mail] wrote:

Whatever it is, it seems to have some kind of a constant refresh rate,
like every shake happens on every even frame so it's like 15 shakes per
second. Dunno if that helps narrowing down the issue with the debugger.

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[hrydgard]

My guess is that the game tries to align the feet with the slope of the ground using some math which goes wrong somewhere. The thing where it gets worse the farther from the origin would suggest some floating point precision issue. It might be doing two operations during the alignment, one forward and the inverse of it, and they are subtly different enough for things to blow up. Or it may be a completely different problem... I mean, it could even be some sort of OS timing issue where the feet alignment code gets run at the wrong time of the frame, but seems unlikely.

We already have tests that make sure that all or most VFPU instructions work the same as on the real thing but there might be something we missed, and we know that the precision of many instructions is not perfect (vsin, vcos, vrot, mmul, vdot for example), while close.

My plan for digging into this would look something like this:

• Make a log of all FPU and VFPU instructions used by the game.
• Switch to interpreter (for ease of modification)
• Subtly sabotage all the logged instructions, one by one, to give a slightly wrong value. If one makes the shake look similar but simply worse, that might be a likely culprit.
• Write really detailed tests for that instruction, run on a real PSP and see if we can get closer.

Step 3 may or may not reach any kind of conclusion so it is a bit of a wild goose chase...

[justm34evah]

Sounds great! Looking forward to your test results.

On Nov 9, 2017 10:30 AM, "Henrik Rydgård" [e-mail] wrote:

My guess is that the game tries to align the feet with the slope of the
ground using some math which goes wrong somewhere. The thing where it gets
worse the farther from the origin would suggest some floating point
precision issue. It might be doing two operations during the alignment, one
forward and the inverse of it, and they are subtly different enough for
things to blow up. Or it may be a completely different problem... I mean,
it could even be some sort of OS timing issue where the feet alignment code
gets run at the wrong time of the frame, but seems unlikely.

We already have tests that make sure that all or most VFPU instructions
work the same as on the real thing but there might be something we missed,
and we know that the precision of many instructions is not perfect (vsin,
vcos, vrot, mmul, vdot for example), while close.

My plan for digging into this would look something like this:

• Make a log of all FPU and VFPU instructions used by the game.
• Switch to interpreter (for ease of modification)
• Subtly sabotage all the logged instructions, one by one, to give a
  slightly wrong value. If one makes the shake look similar but simply worse,
  that might be a likely culprit.
• Write really detailed tests for that instruction, run on a real PSP
  and see if we can get closer.

Step 3 may or may not reach any kind of conclusion so it is a bit of a
wild goose chase...

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[hrydgard]

Didn't say I was going to do it anytime soon... Priority is stabilizing Vulkan and getting 1.5 out there. It's such a massive boost that it's a shame to only have it in dev builds... For example, Tekken 6 runs at or near 60fps on S8.

But if anyone else want to give it a shot now, go ahead :)

[justm34evah]

That's a bit sad, but sure, you do what's necessary. Perhaps someone else
will give it a try. I for one, have no programming skills.

On Nov 9, 2017 3:03 PM, "Henrik Rydgård" [e-mail] wrote:

Didn't say I was going to do it anytime soon... Priority is stabilizing
Vulkan and getting 1.5 out there.

But if anyone else want to give it a shot now, go ahead :)

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[leopard20]

@hrydgard
Sorry for bringing this up again. It must've given you guys quite a headache!

Just wondering if you are gonna test your above theory any time soon, since Vulkan is out and nearly perfect (at least in my opinion).

[LunaMoo]

Testing floating point accuracy might not be a complete waste of time, but I suspect wouldn't lead to fixing this game as it might as well be just a "simple" timing issue which as we know affects a lot of games, where it's not about 2 + 2 not equaling 4, but about 2 being added to 4 and equaling 6 aka the math is probably correct, it just runs some of that math at wrong time getting unexpected results. If math was wrong it would more likely affect all animations or at least all frames of same animation, but that's not the case.

Anyway this issue is soo long and has soo many annoying bumping and requests, it doesn't seem worth wasting a weekend over staring at disassembly:P.

[leopard20]

Yeah I think you're right. I just figured maybe it was worth giving a shot, since this is such an old issue (and probably one of the most anticipated fixes). Still it's nothing game breaking. Just a bit distracting (only if you're standing still, and again only in some stages).

[Gamemulatorer]

@LunaMoo In Tekken 6 (ULUS10466): Fighters' legs tremble/shudder/"flicker" in battle I never experienced that since I use this cheat code that lock the fps to 30 I tried both Practice Stage Walls & No Walls and 5-10 minutes. My phone only Support OpenGL backend :)
_C1 Force 30 FPS [Fixed]
_L 0xE0030064 0x001C239C
_L 0xE002001E 0x103E4B40
_L 0x203E4B40 0x0000001E
_L 0x20022EE4 0x3D088889//2/30=0.03333
_L 0x20452890 0x00000002
_L 0x20452890 0x00000000//FPS

[justm34evah]

30 fps? Ugh.

On Wed, 11 Apr 2018, 04:07 Jinzombie, [e-mail] wrote:

@LunaMoo https://github.com/LunaMoo In Tekken 6 (ULUS10466): Fighters'
legs tremble/shudder/"flicker" in battle I never experienced that since I
use this cheat code that lock the fps to 30 I tried both Practice Stage
Walls & No Walls and 5-10 minutes. My phone only Support OpenGL backend :)
_C1 Force 30 FPS [Fixed]
_L 0xE0030064 0x001C239C
_L 0xE002001E 0x103E4B40
_L 0x203E4B40 0x0000001E
_L 0x20022EE4 0x3D088889//2/30=0.03333
_L 0x20452890 0x00000002
_L 0x20452890 0x00000000//FPS

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[Gamemulatorer]

@justm34evah my GPU (Mali-450) is to weak to get 60 FPS that's why I use 30 FPS cheat code atleast I never experienced the flicker/shudder/tremble in fighters leg 😅

[paulodeleo]

@Jinzombie can you confirm that you can't reproduce the tremble legs bug using this 30 FPS cheat, on the same conditions as this video that I demo it (stage with no walls, tremble legs effect increase as characters get far from the initial center position and than go back to center)?

That would be a confirmation that, somehow, FPS has something related to the issue and, maybe, this information can help leading to a possible fix.

[leopard20]

This cheat code is for the Japanese version of the game though. Maybe it's different than the US and EU version. Maybe the Japanese version doesn't have this issue at all.

[justm34evah]

Omoshiroi...

On Wed, 11 Apr 2018, 16:08 Leo, [e-mail] wrote:

This cheat code is for the Japanese version of the game though. Maybe it's
different than the US and EU version. Maybe the Japanese version doesn't
have this issue at all.

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[leopard20]

I tried some 30 FPS cheats on the US version and it didn't solve anything (also tried frameskipping 1, which is kinda the same as using a 30 FPS cheat). Maybe later I'll test the Japanese version (gotta download it first)

[leopard20]

Well, I tested the EU, US and JP versions and all of them had this issue.
Also, the above code doesn't work in any of them.

[Gamemulatorer]

[Gamemulatorer]

@leopard20 My tekken 6 is USA version and sorry to tell you guys that you need to set the refresh rate to 17 to make it effective.

[leopard20]

That's the modded version! Not the original version.

Maybe that's why it works for you.

[Gamemulatorer]

@Leopard20 Maybe 😅

[paulodeleo]

If the modded version unintentionally fixes the bug, I read it as some kind of progress...

[leopard20]

I watched a couple of YouTube videos of this modded version. The bug was still there.
@Jinzombie Do you think you could record a minute of the game as proof?

[TheConfuZzledDude]

Just thought I'd chime in here just to say that this isn't a purely graphical glitch, it seems to actually affect the hitboxes, which seems strange.

Video here: https://youtu.be/Jy43rya0RNU

[leopard20]

@hrydgard Would be nice to finally fix it by 1.7.0.

[hrydgard]

Would be nice if someone could figure out what the problem is :/

It's pretty clearly CPU emulation related though, especially if it affects the hitboxes.

[leopard20]

@hrydgard I would give it a chance but I don't really know what I should look for!
@weihuoya You seem to be pretty good at debugging! Any ideas about this issue?

[leopard20]

More findings:
The direction of the shaking changes with the fighters' direction. It's like the legs are being pulled towards (or maybe away from) the center!
In this video, the fighters are originally aligned towards the origin. Watch what happens: (also notice the frequency of the shaking - it happens every 1 second or so)
https://www.dropbox.com/s/3wj8qmfo9ts0fq4/20180607_165700.mp4?dl=0
The video is recorded @ 60FPS so you can slow it down to see it in better detail! (you should download it first and watch it with a good video viewer - Dropbox doesn't support slowdown)

[weihuoya]

have no idea about it.
maybe we can decompile it, and see how it works. :sweat_smile:

1)  Dump eboot.bin of the game using UMDGen
2)  Decrypt it if it isn’t yet using pspdecrypter
3)  Output the assembly code with: prxtool –w eboot.bin > eboot.asm
4)  Find the module name with: prxtool –m eboot.bin
5)  Output pseudo code with: pspdecompiler –c eboot.bin > eboot.c

[leopard20]

@weihuoya I dunno... Seems a bit impractical to me! Can you imagine reading and figuring out all that stuff?! 😵
@hrydgard What do you think?

[unknownbrackets]

Just noting here for posterity (sorry for the notifications, this isn't a fix):

This seems to potentially be related to #12082. It was found that on ARM, vmmul retaining too much precision made the shaking of the legs worse. A recent change in the latest git build should have reduced this, probably to the same level as Windows/Linux/Mac builds.

Please don't reply asking if this means a fix is coming: it doesn't necessarily, but it is a lead on the cause. More will be noted in this issue if more progress is made.

-[Unknown]

[hrydgard]

We've now confirmed that the lead was correct - with more PSP-accurate emulation of vmmul and similar instructions, the leg shaking stops completely. It's a lot more complex than just the difference between the previous ARM and ARM64 implementations though, see #2990.

Still a ways to go before we can merge the new code, there's more accuracy work to be done and we need to write a faster implementation once all the edge cases have been figured out, then if it's still too slow we might only enable it for certain affected games. Or, more ideally, we might disable it only for really performance-challenged games that don't need it.

But it's looking good indeed.

[hrydgard]

This should now be fixed with https://github.com/hrydgard/ppsspp/pull/12217 merged.

[unknownbrackets]

Just a heads up for @gid15 - this is related to dot product floating point accuracy.

-[Unknown]

[hrydgard]

Was playing around with some perf stuff (https://github.com/hrydgard/ppsspp/compare/vfpu-dot-experiments?expand=1) when I realized that the ReadMatrix/WriteMatrix functions in the interpreter are very slow and might hurt more than the actual computation. Those can be special-cased and optimized which might give us enough speed back.

[hrydgard]

Some profiling shows that vfpu_dot is considerably heavier than the ReadMatrix/WriteMatrix calls, but that they indeed shouldn't be overlooked for optimization.

[tabnk]

Finally (so many years) it FIXED shaking leg issue for both Tekken Dark and Tekken 6. Importantly no much performance hit on both my PC and Android build.

[Gamemulatorer]

@tabnk Tekken5 doesn't have a bug in CPU emulation 🤔

[thedax]

Great to finally see this fixed. It was one of the oldest outstanding issues, IIRC.

[ssinenominee]

Great to finally see this fixed. It was one of the oldest outstanding issues, IIRC.

please how do I fix this in layman terms, I don't understand any of the jargon used in the merged threads that fixes the issue.
Could I PLEASE get a step 1-10? *in layman terms, like what I have to do and where I have to go.
SORRY that you have to hold my hand...
Thanks a lot for helping me play PSP games guys...you rock!

I have the latest build (1.8.0)

[leopard20]

@ssinenominee What steps? Just download the latest build from here:
http://ppsspp.org/downloads.html

Go to the bottom of the page and download the latest development build. (latest as of now: 1.8.0-560)

[ssinenominee]

@ssinenominee What steps? Just download the latest build from here:
http://ppsspp.org/downloads.html

Go to the bottom of the page and download the latest development build. (latest as of now: 1.8.0-560)

ROFL....thanks a lot man, didn't know it was that easy. I appreciate it. Godspeed

[proganime1200]

still happening

[hrydgard]

@proganime1200 What version of PPSSPP are you using? Can you check the game ID of your Tekken 6 iso? This really shouldn't be happening anymore.

[HeriKuen]

Thanks I tried VFPU_MTX in the checklist position, the problem was resolved, thank you all...

[hrydgard]

I see a few mods have popped up: https://report.ppsspp.org/games?name=tekken

Were you simply playing one of those?

[HeriKuen]

Yes Tekken 6 The beginning went well without a hitch, but in some arenas it still experiences the same bug.