Igalia Posts Intel vertex_attrib_64bit Mesa Driver Patches, Close To OpenGL 4.1+

[bridgman]

Yeah true, if it's the same few teams porting games to Linux then it doesn't make much difference what everyone else does. Fair point.

[smitty3268]

There's a third option which AFAIK is most commonly used - find the highest GL level where you need most of the functions, "require" that GL version, and then check individually for the (typically small) number of functions required on top of that GL version.

A lot of games really do use tons of GL4 functions though.

That's not a bug, it's them using modern features and expecting the drivers to provide them.

[bridgman]

A lot of games really do use tons of GL4 functions though. That's not a bug, it's them using modern features and expecting the drivers to provide them.

Are you saying that the Intel drivers support all those GL functions but just not the GL level ? If so then yeah I agree that makes things difficult, although at least it's a fairly short-term thing. If not then it doesn't matter... pick the specific 4.x level that covers most of the functions and check extensions for the rest.

[smitty3268]

Are you saying that the Intel drivers support all those GL functions but just not the GL level ?

Yes, that's exactly correct.

However, there's a strong argument to be made that Intel gpu's are too slow to give decent performance on those apps anyway, so it's perhaps not a big deal. It was certainly more of an issue for radeonsi.

[Passso]

There's a third option which AFAIK is most commonly used - find the highest GL level where you need most of the functions, "require" that GL version, and then check individually for the (typically small) number of functions required on top of that GL version.

True, best option.
But a lot of Linux games of mine sticks with "OpenGL version -> stop". On same hardware on Windows they launch, so I presume game porters do not handle cases...

[bridgman]

A lot of Windows games used to implement support for two major versions, DX11 falling back to DX9 at the time. There was a trend towards doing that with OpenGL as well (latest falling back to the 2.1/GLES 2 common functionality) but I haven't seen that as much recently.

Main difference AFAICS is that WHQL cert tends to herd the industry into aligning on a couple of major inflection points with vendor-specific caps at each point, while GL has more inflection points and more variability (extensions implemented on the way to the next level) at each level as well.

It would have been nice if the previous common ground had corresponded to a specific GL level (rather than corresponding to a specific DX level as it did due to available HW features) but I guess progress on GL level support moved faster than standardization on an older level, which isn't an entirely bad thing. I guess (3.3 plus the DX compatibility extensions from 4.x) would have been the next logical fallback level.