Enable OpenGL software rendering on macOS

Mon May 2 08:31:43 UTC 2022

Hi Jose,

Many thanks for your answer.

JOGL classes enabling GL binding macOS all refer to CGL, so yes, I think I want to rely on CGL (there is however in JOGL a couple of classes allowing to work with X11, but they're used on Linux only).

I can't access the Apple M1 on which I built Mesa right now, but homebrew on another macOS provides libGL and not libGLX.

ls /usr/local/Cellar/mesa/21.1.2/lib

drilibGL.dyliblibGLESv1_CM.dyliblibGLESv2.dyliblibglapi.dylib

libGL.1.dyliblibGLESv1_CM.1.dyliblibGLESv2.2.dyliblibglapi.0.dylibpkgconfig

One motivation for enabling Mesa on macOS is actually the deprecated status of OpenGL. I would expect this software implementation of GL to simply provide an image to be copied to a native window/frame, without having to rely on CGL. Hence, one could continue working with simple OpenGL even if macOS doesn't provide such API.

Does it sound reasonable?

Martin

Envoyé avec la messagerie sécurisée [ProtonMail](https://protonmail.com/).

------- Original Message -------
Le vendredi 29 avril 2022 à 16:08, Jose Fonseca <jfonseca at vmware.com> a écrit :

> The difficulty with OpenGL on macOS is that all driver interfaces are both undocumented and deprecated.
>
> If you want to override the system OpenGL, you can use apitrace code as reference. There are two approaches:
>
> - DYLD_FRAMEWORK_PATH https://github.com/apitrace/apitrace/blob/master/cli/cli_trace.cpp
> -  DYLD_INSERT_LIBRARIES https://github.com/apitrace/apitrace/tree/dyld-interpose (experimental branch)
>
> AFAIK, Mesa build for macOS generates a ibGLX which depends on X11, which is probably not what you want. You want to use Mesa for macOS apps which use CGL as opposed to GLX, right?
>
> So, if one wants to have a SW renderer on macOS with llvmpipe without depending on X11, then one would need to implement:
>
> - a new [Gallium frontend](https://gitlab.freedesktop.org/mesa/mesa/-/tree/main/src/gallium/frontends) that implements CGL API (equivalent to the WGL frontend that exists for Windows)
> - a new [SW renderer winsys](https://gitlab.freedesktop.org/mesa/mesa/-/tree/main/src/gallium/winsys) that draws pixels to Cocoa window somehow (equivalent to the GDI winsys that draws to a Windows GDI surface)
>
> It's not a matter of just integrating existing components together -- there's lot of new code that would be need here -- I'd reckon 2 months for somebody familiar with Mesa/macOS, 6 - 12 months for somebody more novice. And let's be frank, given mac deprecation of OpenGL and migration away from Intel to Arm, the usefulness of this in the long term is dubious.
>
> Jose
>
> ---------------------------------------------------------------
>
> From: mesa-dev <mesa-dev-bounces at lists.freedesktop.org> on behalf of Martin Pernollet <martin.pernollet at protonmail.com>
> Sent: Friday, April 29, 2022 12:32
> To: mesa-dev at lists.freedesktop.org <mesa-dev at lists.freedesktop.org>
> Subject: Enable OpenGL software rendering on macOS
>
> ⚠ External Email
>
> TLDR : I failed using Mesa software rendering on macOS. I am looking for advice to invoke mesa's libGL.dylib without relying on macOS's system GL.
>
> Hi everyone,
>
> I am building (java) software involving Mesa for CPU rendering. I use CPU rendering as fallback when JOGL (OpenGL binding for Java) fail to use the GPU natively. This is sometime the case for old Linux distributions, this will certainly be frequent on macOS in the future due to Apple's OpenGL deprecation.
>
> Mesa CPU rendering is working great on Ubuntu (by enabling LIBGL_ALWAYS_SOFTWARE=true) and Windows (by simply loading Mesa's DLL instead of system DLL, no need to ask for software mode).
>
> I however thrive to useMesa's software rendering on macOSfor the following reasons
>
> - Spying dynamic library load sequence shows that whenever Mesa's libGL.dylib is loaded, Apple Metal and libGL.dylib are loaded before, even when using DYLD tricks to ensure Mesa get loaded before any other library (except the Java VM) [1] Someone says that Mesa's macOS implementation relies on system GL [4]. I noticed that when enabling LIBGL_ALWAYS_SOFTWARE=true, this activates Apple software rendering but not Mesa's software rendering [5].I wonder how I could avoid this and use a pure Mesa's OpenGL implementation in this situation.
> - When getting out of the java World
>
> - Running a pre-built glxgear/glxinfo installed through MacPorts only allows using Apple's libGL.dylib but not Mesa's libGL.dylib [2].
> - Building glxinfo myself by linking explicitely to Mesa's GL + X11 lead to an X11 error that I am not able to depict [3].
>
> This has been discussed already on Khronos community [1] but I have no clue how to go further. I hope some experts here can help me solve this!
>
> Thanks in advance,
>
> Martin
>
> [1] [https://community.khronos.org/t/failing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library/108408](https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommunity.khronos.org%2Ft%2Ffailing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library%2F108408&data=05%7C01%7Cjfonseca%40vmware.com%7C0282a06768b14d74e2d008da29d3ff8f%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637868287773929833%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=TCTGtFzds%2FhFJRjrcj4xjALQ5vuZn0X8NekXJxJIF8Y%3D&reserved=0)
> [2] [https://community.khronos.org/t/failing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library/108408/14](https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommunity.khronos.org%2Ft%2Ffailing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library%2F108408%2F14&data=05%7C01%7Cjfonseca%40vmware.com%7C0282a06768b14d74e2d008da29d3ff8f%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637868287773929833%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=%2Bhy73iogAkMSiYOcSTBXjF8Rh80LBcv%2Ffj7%2B9%2Bm2Tdw%3D&reserved=0)
> [3] [https://community.khronos.org/t/failing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library/108408/19](https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommunity.khronos.org%2Ft%2Ffailing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library%2F108408%2F19&data=05%7C01%7Cjfonseca%40vmware.com%7C0282a06768b14d74e2d008da29d3ff8f%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637868287773929833%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=MkMiH9Hc9hMSmv0%2FM5Klk4EyouR4OBz3wXk8nP30Q1A%3D&reserved=0)
> [4] [https://community.khronos.org/t/how-to-use-opengl-on-zink-mesa-moltenvk-and-macos/108160/18](https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommunity.khronos.org%2Ft%2Fhow-to-use-opengl-on-zink-mesa-moltenvk-and-macos%2F108160%2F18&data=05%7C01%7Cjfonseca%40vmware.com%7C0282a06768b14d74e2d008da29d3ff8f%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637868287773929833%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=KkXEuBfzxSBxfZ2oRDGh%2FR6jKc5i9wqiMjcgsmJUoBI%3D&reserved=0)
> [5] [https://community.khronos.org/t/failing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library/108408/17](https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommunity.khronos.org%2Ft%2Ffailing-to-load-mesa3d-on-macos-instead-of-macos-provided-opengl-library%2F108408%2F17&data=05%7C01%7Cjfonseca%40vmware.com%7C0282a06768b14d74e2d008da29d3ff8f%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C1%7C637868287773929833%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=YCxes9WhHixFGK73kliu4ELFfMQXoIfbZ%2BeMeU8U1HA%3D&reserved=0)
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