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About rounding mode/clamping
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Nexxxus Offline
GlideGS
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Post: #1
About rounding mode/clamping
I know that the rounding modes and clamping helps to get the floats more accurate.

As for Final Fantasy X:

setting rounding mode to negative OR setting clamping to FULL fixes the bug that characters stand in the wrong position.
But do I need both to get it more accurate or is clamping to full enough?

I'm playing with default settings except clamping to full, this fixed the issue that the characters stand in the wrong position BUT I already discovered another bug:
When Tidus completed the cloister of trials on Besaid, Wakka appears and walks on to the Elevator.
Tidus suddenly dissapears and appears again when the elevator goes down.
Is that a side effect due to clamping?

And what about VU clamping/rounding mode? does it fix gameplay issues or only graphics (SPS,etc...) ?

What would the best setting for FFX? rounding mode negative/clamping full
or is it enough to use rounding mode negative and normal clamping?

And I have no idea which rounding mode is most accurate.

Would be nice if someone of the devs could explain this Smile


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(This post was last modified: 10-09-2011 07:52 PM by Nexxxus.)
10-09-2011 07:50 PM
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abdo123 Offline
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Post: #2
RE: About rounding mode/clamping
FROM THE GUIDE :

Core settings

Next are the Core PCSX2 settings which can be found under Config =>Emulation settings. You'll see a window like this(click to enlarge):

[Image: attachment.php?aid=26073]


There are 6 tabs, EE/IOP, VUs, GS, GS Window, Speedhacks and Gamefixes. We'll start with EE/IOP.

EE/IOP tab of the Emulation Settings:

EE/IOP stands for Emotion Engine / Input Output Processor which are the core components of the Playstation 2. Below we'll describe the settings available to us:

Emotion Engine: Select "Recompiler" to enable the recompiler for the Emotion Engine, granting a really big speedup. It's extremely compatible, so you should always use it. By selecting "Interpreter" you will be using the really slow Interpreter mode, which in some cases is more compatible, but is mainly there for debugging purposes.

IOP: Same settings as above for the Input Output Processor. The Interpreter here is not such a huge slowdown as the EE but still a big speed hit.

Round mode: Changes how rounding of float numbers is calculated. If your game is freezing somewhere, try changing the value here. Default and most compatible value here is Chop/Zero. Automatically changed when 'Enable Patches' is checked under System for some games known to need a different value than default.

Clamping mode: These settings go from faster to slower from top to bottom. So 'None' is the fastest but least compatible and 'Full' is the slowest but most compatible. Default value here is 'Normal' which works fine for most games without compromising speed much. Automatically changed when 'Enable Patches' is checked under System for some games known to need a different value than default.

Flush to Zero: Can give a small speed boost but will lower compatibility. Recommended.

Denormals are Zero: Gives a good speed boost and should not cause any problem.

Restore Defaults: Click this to restore all settings to their default values (which are seen as Bold in Vista/Windows 7 or colored green in Windows XP).


VUs tab of the Emulation Settings:

VUs stands for Vector Units which are the co-processors of the Playstation 2 working in parallel with the EE and IOP. The Playstation 2 has 2 of these co-processors called VU0 and VU1. Below we'll describe the settings available to us:

VU0: In this radio box you can choose one of 3 choices: Interpreter, microVU Recompiler and superVU Recompiler [legacy].

Interpreter: By selecting this PCSX2 will use the Interpreter for the VU0 unit, which is extremely slow and not very compatible either. Should only be used for debugging and testing.

microVU Recompiler: The latest recompiler for the Vector Units made by cottonvibes. This option has very high compatibility with games, is more stable and has fair speed. Recommended.

superVU Recompiler [legacy]: The old recompiler for the Vector Units made by zerofrog. This is not actively developed any more (thus the legacy tag), has quite worse compatibility compared to microVU, more unstable and usually a bit faster. Should only be used to identify bugs with the new recompiler or for the rare cases it works better than microVU.

VU1: As above but for Vector Unit 1.

Round mode: Same as EE/IOP

Clamp mode: These settings go from faster to slower from top to bottom. So 'None' is the fastest but least compatible and 'Extra+Preserve Sign' is the slowest but most compatible. Default value here is 'Normal' which works fine for most games without compromising speed much. If you experience spikey polygons or bad geometry, try setting this to 'Extra+Preserve Sign'. Automatically changed when 'Enable Patches' is checked under System for some games known to need a different value than default.

Flush to Zero: Can give a small speed boost but will lower compatibility. Recommended.

Denormals are Zero: Gives a huge speed boost and should not cause any problem.

Restore Defaults: Click this to restore all settings to their default values (which are seen as Bold in Vista/Windows 7 or colored green in Windows XP).





it should cover the clamping stuffs Wink
10-09-2011 08:45 PM
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Nexxxus Offline
GlideGS
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Post: #3
RE: About rounding mode/clamping
I already read that..
But are there some experiences?
I mean recommendations for FFX or Persona 3/4 for example?


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10-09-2011 08:52 PM
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abdo123 Offline
plant scientist !!!!

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Post: #4
RE: About rounding mode/clamping
you asked for the most compatible mode and that what i said Mellow


(10-09-2011 08:45 PM)abdo123 Wrote:  FROM THE GUIDE :

Clamping mode: These settings go from faster to slower from top to bottom. So 'None' is the fastest but least compatible and 'Full' is the slowest but most compatible. Default value here is 'Normal' which works fine for most games without compromising speed much. Automatically changed when 'Enable Patches' is checked under System for some games known to need a different value than default.


Clamp mode: These settings go from faster to slower from top to bottom. So 'None' is the fastest but least compatible and 'Extra+Preserve Sign' is the slowest but most compatible. Default value here is 'Normal' which works fine for most games without compromising speed much. If you experience spikey polygons or bad geometry, try setting this to 'Extra+Preserve Sign'. Automatically changed when 'Enable Patches' is checked under System for some games known to need a different value than default.







it should cover the clamping stuffs Wink

Anyway the only "experience" i had with this was the Tekken 5 brakes with none ( should be at least normal )
(This post was last modified: 10-09-2011 09:03 PM by abdo123.)
10-09-2011 08:57 PM
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Shadow Lady Offline
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Post: #5
RE: About rounding mode/clamping
(10-09-2011 08:52 PM)Nexxxus Wrote:  Persona 3/4 for example?

What about it? do they need different modes?

Quote:does it fix gameplay issues or only graphics (SPS,etc...) ?

Yeh, could fix gameplay issues, characters facing the wrong way in FFX is a gameplay issue not just a graphical one.

Quote:What would the best setting for FFX? rounding mode negative/clamping full
or is it enough to use rounding mode negative and normal clamping?

Try it and tell us, as far as I know setting it to negative could make a couple scenes make your character move in the wrong direction while full clamps could be only the slowdown it gives or could give another different issue.


It depends on the game really, some games don't work correctly with full clamps but work with "none" or "normal" instead, but generally "the higher, the better" rule applies.

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10-10-2011 03:40 AM
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Nexxxus Offline
GlideGS
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Post: #6
RE: About rounding mode/clamping
(10-10-2011 03:40 AM)Shadow Lady Wrote:  Yeh, could fix gameplay issues, characters facing the wrong way in FFX is a gameplay issue not just a graphical one.
was talking about VU rounding/clamping.
I know that EE rounding/clamping fixes this problem.


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10-10-2011 04:25 AM
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rama Offline
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Post: #7
RE: About rounding mode/clamping
Nexxxus:
The fundamental issue is that we're emulating the EE FPU and the 2 Vector Units using x86 SSE.
There is a slight difference in how the PS2 and x86 SSE round floating point values.
PS2 games normally should not break because of this, but there are a couple that do, for various reasons.

Now, SSE allows us to configure 4 different modes of rounding.
The "Chop" mode comes closest to what a PS2 does, but it's not perfect either.

In those cases where "Chop" produces different results than what the game wanted to see, you can try the other 3 modes.
10-10-2011 01:48 PM
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