Virgil 3D renderer on macOS

[小田喜陽彦]

Hi,

I would like to introduce my Virgil 3D renderer port to macOS.

Some patches which are made in the process are useful even without
Virgil 3D renderer, and already submitted to upstreams:
- [PATCH] ui/cocoa: Support unique keys of JIS keyboards
- [PATCH] ui/cocoa: Remove the uses of full screen APIs
- [PATCH] ui/cocoa: Do not copy members of pixman image
- [PATCH] ui/cocoa: Interpret left button down as is when command is pressed
- Support ANGLE on macOS by akihikodaki · Pull Request #239 · anholt/libepoxy
  https://github.com/anholt/libepoxy/pull/239

I will send other patches when I confirm they do not cause harm on
Linux hosts, or changes they depend on get merged.

The complete source code is available on GitHub:
https://github.com/akihikodaki/libepoxy/tree/macos
https://github.com/akihikodaki/qemu/tree/macos
https://github.com/akihikodaki/virglrenderer/tree/macos

The "cocoa" display of QEMU will provide OpenGL support to the guest
on macOS hosts. "NSOpenGLContext" (which wraps "CGL") will be the
backend for core profile. ANGLE (which also wraps CGL and provides
compatibility improvements) will be the backend for ES profile. It is
possible to build without ANGLE, but such a build will lose ES profile
compatibility.

Videos captured on M1 MacBook Air are available on YouTube:
https://youtu.be/ezvQPREjN1s (The WebGL Aquarium on the host, for comparison)
https://youtu.be/iOG9Dbn8VoE (QEMU with OpenGL Core)
https://youtu.be/k0bVlVQU2JQ (QEMU with OpenGL ES)

glmark2 gives 577 scores for gl=es and 151 scores for gl=off. The FPS
of the WebGL aquarium with identical configurations was consistent
with the display on the host (60 FPS), 15 FPS with gl=es, 8 FPS with
gl=off.

I have not ran a formal conformance tests, but gl=core (which uses
NSOpenGLContext) had a few problems:
- glmark2 fails with the following output:
> vrend_compile_shader: context error reported 6 "glmark2" Illegal shader 0
> shader failed to compile
> ERROR: 0:2: '' :  extension 'GL_ARB_fragment_coord_conventions' is not supported

- Mozilla Firefox opening "about:support" fails with the following
output on the host (This one should be easy to fix but I rather not
because I also have gl=es.):
> No provider of glTexStorage2DMultisample found.  Requires one of:
>     Desktop OpenGL 4.3
>
>     GL_ARB_texture_storage_multisample
>     OpenGL ES 3.1

In contrast, gl=es, backed with ANGLE, runs properly as far as I have seen.

My motivation is to make Linux desktop usable on M1. Patches to add
Hypervisor framework support on Aarch64 are already submitted ("hvf:
Implement Apple Silicon Support") and they are indeed useful for
various workloads and I also used them to port Virgil, but I also
needed graphics acceleration for my purpose. Another attempt to get
Linux work on M1 is Asahi Linux, which aims to run Linux bare-metal.
Of course, this needs porting graphic stacks to M1 and is likely to
take time. I am satisfied with my port for the purpose although there
may be rooms for performance or compatibility improvements.

There is nothing preventing that if anyone would like to use Virgil on
Intel Macs. Also, some patches may benefit other OpenGL ES
configurations and displays.

Thanks,