Quoting: syxbitArt makes me think of sunset riders. Man I wish they did an HD remake of that.

And Shank!

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Wow, impressive. So they have written their own Sega Genesis emulator as well while being able to add achievements from the rom. Instabought this one.

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Yet again I don't understand why some devs don't code cross platform from the start and test on every platform, it's a good way to catch bugs and problems that you never knew you had which in the end leads to a more stable product on all platforms.

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Quoting: x_wing

Quoting: F.UltraAccording to https://lists.freedesktop.org/archives/mesa-dev/2017-June/160362.html [External Link] the GLSL specs (where this is happening) says that "derivatives are undefined after non-uniform discard" so you could argue that this use is forbidden (if you act like a GCC developer) or that it's a grey area.

I'm a complete ignorant about OpenGL nor graphics APIs, but how hard would be to specify an OGL extension to address this issue? Is Khronos group a problem to create such extension?

From my point of view, Mesa will not accept to change anything if they don't get some clarification from the standard and I remember that Malek mention this as a possible solution (if I didn't get him wrong).

I don't know either. Anyway there exists now a drirc setting so if any game continues to use this use-after-free functionality they can always be added to drirc for the workaround.

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Quoting: x_wing

Quoting: Guest

Quoting: F.UltraSo Mesa should just focus on being bug for bug compatible with nVidia?

You're focusing on bashing Nvidia again. Let me make it clear.

The Nvidia binary driver on Linux has this behavior
AMD's Catalyst driver on Linux has this behavior
All of the OS X OpenGL drivers - for AMD, Nvidia and Intel have this behavior.
Metal on OS X has this behavior.

MESA is the odd one out.

You can argue semantics all you like, but if the situation was reversed e.g. Nvidia was "following spec" and MESA was "doing the popular thing", you'd be screaming for Nvidia to "fix it".

The question here is: what says OpenGL specs about this behavior? Is Marek wrong with his statement? There is no point to say that others drivers works to a project and devs that are very pedantic with what is stated in papers (you're allowed to quote Torvalds for this behavior :p ).

Is there anyway to optimize the workaround they have in radeonsi? Sounds like that we have a solution but it strongly hits performance.

According to https://lists.freedesktop.org/archives/mesa-dev/2017-June/160362.html [External Link] the GLSL specs (where this is happening) says that "derivatives are undefined after non-uniform discard" so you could argue that this use is forbidden (if you act like a GCC developer) or that it's a grey area.

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Quoting: jens

Quoting: F.Ultra

Quoting: Guest

Quoting: F.UltraThat it works on the nVidia driver is proof of exactly nothing. nVidia is known for adding support for broken behaviour and the problem for Mesa here is if they are to be following the OpenGL specifications or if they are to allow nVidia to dictate the OpenGL specifications.

Unfortunately many game devs use nVidia so they don't know that they are not following the specs since it "just works".

Yawn. You completely missed the part where I said it works on OS X's GL drivers too then. On ALL GPU's there. Also it worked on Catalyst. Nice one in turning it into an opportunity to bash Nvidia though.

Just so you know.. my main Linux box has an AMD card in it.

If we look at the changelog from Marek when this particular drirc override was implemented it looks quite clear to be a bug in all the other drivers that accept this behaviour for OpenGL yes:

Rocket League expects DirectX behavior for partial derivative computations after discard/kill, but radeonsi implements the more efficient but stricter OpenGL behavior and that will remain our default behavior. The new screen flag forces radeonsi to use the DX behavior for that game.

I don't see the word "bug" anywhere in your quote. From my own experience (not with graphics api's though), like @mirv already pointed out, complex specification will always contain some minor gray areas where interpretation differences may occur. Combine that with lots of moving targets and needed time for stabilization for the specification itself during development, it is then rather the exception that something "just" works according to specs ;). I don't know all the details here, but sometimes there is no right or wrong. I guess that the mesa devs had a similar conclusion since they implemented a switch for this behavior. I have an NVidia card but I'm happy that mesa got in such a good shape recently and that lot's of AMD people can enjoy e.g. Feral, VP and other ports.

The switch was added because it was easier to implement the work around via a drirc setting than change the behaviour in Rocket League (where the problem that lead to the setting originated) due to the DX->OpenGL translation and the main problem here is that there exists a difference in how DX and OpenGL handles this, aka Marek was just a nice guy here.

You don't see the word "bug" explicitly but the wording is still "radeonsi implements the ... OpenGL behaviour" which can not be read in any other way than this not being according to OpenGL specifications. nVidia probably handles it like DX due to similar code paths in their driver. No one is accusing nVidia of deliberately implementing it this way to create problems for mesa/radeon.

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Quoting: Guest

Quoting: F.UltraThat it works on the nVidia driver is proof of exactly nothing. nVidia is known for adding support for broken behaviour and the problem for Mesa here is if they are to be following the OpenGL specifications or if they are to allow nVidia to dictate the OpenGL specifications.

Unfortunately many game devs use nVidia so they don't know that they are not following the specs since it "just works".

Yawn. You completely missed the part where I said it works on OS X's GL drivers too then. On ALL GPU's there. Also it worked on Catalyst. Nice one in turning it into an opportunity to bash Nvidia though.

Just so you know.. my main Linux box has an AMD card in it.

If we look at the changelog from Marek when this particular drirc override was implemented it looks quite clear to be a bug in all the other drivers that accept this behaviour for OpenGL yes:

Rocket League expects DirectX behavior for partial derivative computations after discard/kill, but radeonsi implements the more efficient but stricter OpenGL behavior and that will remain our default behavior. The new screen flag forces radeonsi to use the DX behavior for that game.

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Quoting: Leopard

Quoting: F.Ultra

Quoting: Guest

Quoting: sonicYou says that is Mesa bug, but from Mesa devs response I am no so sure. And lets be honest, this is mainly caused by the d3d->ogl translation layer.

It is, and the proof is that it does not happen on the Nvidia driver, nor does it happen under MacOS under OpenGL. D3D->GL has nothing to do with it.

That it works on the nVidia driver is proof of exactly nothing. nVidia is known for adding support for broken behaviour and the problem for Mesa here is if they are to be following the OpenGL specifications or if they are to allow nVidia to dictate the OpenGL specifications.

Unfortunately many game devs use nVidia so they don't know that they are not following the specs since it "just works".

Can we stop this please?

Just because of that nonsense attitude , AMD users are still suffering when try to play Dying Light like games.

Is your goal running all games you have without issues as a gamer or caring about driver hacks etc?

So Mesa should just focus on being bug for bug compatible with nVidia? I agree that it's frustrating as a gamer to not have your game work due to Mesa refusing to implement a bug that just happens to exist in nVidia but at the same time the real problem lies in the game, if games would just also test with Mesa on AMD then a lot of bugs in games could have been fixed before product launch (which would produce a much higher quality product in the end).

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Quoting: Guest

Quoting: sonicYou says that is Mesa bug, but from Mesa devs response I am no so sure. And lets be honest, this is mainly caused by the d3d->ogl translation layer.

It is, and the proof is that it does not happen on the Nvidia driver, nor does it happen under MacOS under OpenGL. D3D->GL has nothing to do with it.

That it works on the nVidia driver is proof of exactly nothing. nVidia is known for adding support for broken behaviour and the problem for Mesa here is if they are to be following the OpenGL specifications or if they are to allow nVidia to dictate the OpenGL specifications.

Unfortunately many game devs use nVidia so they don't know that they are not following the specs since it "just works".

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Quoting: iiariI have zero horse in the this race, but find it hilarious that the dev implies that:

1) Only the Linux community is toxic (eyeroll). Has he been in, well, almost any other Windows gaming forum at all for the sophomoric, hateful, entitled views there? Hahahaha....

2) Only Linux is a broken platform (eyeroll again). There are so many broken games, compromised engines, etc etc on Windows and, well, every other platform that to pretend it's only us is absurd.

This is because Gary is a Windows guy, he codes on Windows and he uses only Windows. So when he sees toxic comments from Windows people he is just not seeing it but then the same comes from a Linux user then it hits his brain with "well look at that, another toxic Linux luser...".

This is just how the human brain works. If you are a meat-eater and you see a single Vegan doing something crazy -> all vegans are crazy. And if you are a die hard Linux fan then you can experience one bug every single day without recording it but try Windows/macOS once and hit a single bug and "I knew it, this whole system is FUBAR".

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