Get better OpenGL version than 2.1 on macOS #3895

metayan · 2023-04-05T14:34:06Z

Normally macOS gives us only OpenGL 2.1, but if we request 3.3 and create a new context, we get the best OpenGL version it has to offer.

Before:
INFO: Renderer: opengl
INFO: OpenGL version: 2.1 NVIDIA-14.0.32 355.11.11.10.10.143
WARN: Trilinear filtering disabled (OpenGL 3.0+ or ES 2.0+ required)

After:
INFO: Renderer: opengl
DEBUG: Creating GL Context
INFO: OpenGL version: 4.1 NVIDIA-14.0.32 355.11.11.10.10.143
INFO: Trilinear filtering enabled

when running with
--verbosity=verbose --render-driver=opengl

Note:
Since SDL_CreateRenderer causes a fallback to OpenGL 2.1, the profile and version attributes have to be set and the context created after.
This took a while to figure out.

Normally macOS gives us only OpenGL 2.1, but if we request 3.3 and create a new context, we get the best OpenGL version it has to offer. Before: INFO: Renderer: opengl INFO: OpenGL version: 2.1 NVIDIA-14.0.32 355.11.11.10.10.143 WARN: Trilinear filtering disabled (OpenGL 3.0+ or ES 2.0+ required) After: INFO: Renderer: opengl DEBUG: Creating GL Context INFO: OpenGL version: 4.1 NVIDIA-14.0.32 355.11.11.10.10.143 INFO: Trilinear filtering enabled when running with --verbosity=verbose --render-driver=opengl Note: Since SDL_CreateRenderer causes a fallback to OpenGL 2.1, the profile and version attributes have to be set and the context created _after_. This took a while to figure out.

rom1v

Thank you for your contribution.

Since SDL_CreateRenderer causes a fallback to OpenGL 2.1

Do you know where (in the SDL codebase)?

if we request 3.3 and create a new context, we get the best OpenGL version it has to offer.

What if the latest version available is <3.3? It will fail in that case.

I'm a bit afraid that this change is specific to your machine/drivers, and that it may fail otherwise.

If OpenGL 3 or 4 can be available on macOS, IMO it should even be changed on SDL directly (we can still try to make it work better on scrcpy temporarily).

rom1v · 2023-04-05T17:31:17Z

app/src/screen.c

+        // Persuade macOS to give us something better than OpenGL 2.1
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);


What if OpenGL 3.3 is not available? Is there a way to know which version is available?

Why SDL does not use the latest version availabe?

It's a macOS OpenGL strangeness that SDL seems to have left up to us to solve.
More explained in #3895 (comment) below.

rom1v · 2023-04-05T17:31:46Z

app/src/screen.c

+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+        LOGD("Creating GL Context");
+        SDL_GLContext *gl_context;
+        gl_context = SDL_GL_CreateContext(screen->window);


Probably needs a matching SDL_GL_DestroyContext() somewhere.

Yes. Added SDL_GL_DeleteContext().

This way we get the best available OpenGL version on macOS. Explanation at Genymobile#3895

metayan · 2023-04-05T23:50:05Z

EDIT: Please ignore this - I found a better solution, which I'll push shortly.

Since SDL_CreateRenderer causes a fallback to OpenGL 2.1

Do you know where (in the SDL codebase)?

Found it mentioned at
https://stackoverflow.com/a/23858884
"… SDL lowering the context version is due to the fact that the renderer is implemented with OpenGL 2.1 calls, so it needs to create a 2.1 GL context."

Also discussed at
libsdl-org/SDL#1957
which ends with
"Marking won't fix for now, since the SDL render API doesn't support Core Profile."

if we request 3.3 and create a new context, we get the best OpenGL version it has to offer.

What if the latest version available is <3.3? It will fail in that case.

Changed to select OpenGL 3.2.

According to page 24 of
https://developer.apple.com/opengl/OpenGL-Capabilities-Tables.pdf
all hardware and software renderers can use OpenGL 3.2 since macOS 10.7.5.

Also, when choosing 3.2, I actually get 4.1, which is the highest that my computer supports under macOS:

INFO: Renderer: opengl
DEBUG: Creating OpenGL 3.2 Context
INFO: OpenGL version: 4.1 NVIDIA-14.0.32 355.11.11.10.10.143
INFO: Trilinear filtering enabled

Apparently that is how Apple chose to handle it:
"for macOS you either have 3.2 or 4.1, nothing in between"
from ocornut/imgui#1466 (comment)

A more thorough explanation of macOS OpenGL peculiarities:
ocornut/imgui#1466 (comment)

I'm a bit afraid that this change is specific to your machine/drivers, and that it may fail otherwise.

It seems like it's specific to OpenGL under macOS in general.
For the record, I'm using Catalina (10.15.7).
The change only affects the OpenGL drivers, so those who don't specify --render-driver=opengl get METAL under macOS.

If OpenGL 3 or 4 can be available on macOS, IMO it should even be changed on SDL directly (we can still try to make it work better on scrcpy temporarily).

The option to use higher OpenGL versions under macOS has been available for a long time, and SDL supports using them, but not automagically.

A solution in Lisp, for example, which starts with the highest version and keeps decreasing it until a context is created:
https://github.com/cbaggers/cepl.sdl2/blob/6da5a030db5e3579c5a1c5350b1ffb8fc9950e9a/cepl.sdl2.lisp#L139-L155

metayan · 2023-04-06T00:19:35Z

By only setting the Core Profile for the context, without specifying the OpenGL version, macOS seems to choose the highest available OpenGL version.

I've modified the PR accordingly.

The reason why SDL doesn't do this automagically:

Platform Issue (MacOSX): When MacOSX 10.7 introduced support for OpenGL beyond 2.1, they also introduced the core/compatibility dichotomy. However, they did not introduce support for the compatibility profile itself. Instead, MacOSX gives you a choice: core profile for versions 3.2 or higher, or just version 2.1. There is no way to get access to features after 2.1 and still access the Fixed Function Pipeline.

From https://www.khronos.org/opengl/wiki/OpenGL_Context#OpenGL_3.2_and_Profiles

rom1v · 2023-04-07T06:48:24Z

Thank you for the details 👍

I had a refactor commit related to screen/display on a local branch that I just pushed to dev: 051b74c

I rebased/reapplied your work above. Please check and review branch macos_opengl.

metayan · 2023-04-07T13:31:57Z

Looks good and works now.

rom1v · 2023-04-07T14:26:31Z

You should not have closed it, it's not merged yet, and I cannot reopen since your branch has been deleted :/

I would like other people to test branch macos_opengl (with scrcpy --Vdebug --render-driver=opengl) on macOS before merging 😄

metayan · 2023-04-07T14:32:24Z

Oh, sorry.
Luckily I hadn't deleted it locally yet, so pushed it again.
Reopening. Hope it works.

metayan · 2023-04-07T14:34:40Z

I thought that it's fine to delete, since it's in macos_opengl.
Well, we learn... ;)

metayan · 2023-04-07T14:36:34Z

Should I do something about the "This branch has conflicts that must be resolved" that's being shown at the end of this thread?

By default, SDL creates an OpenGL 2.1 context on macOS for an OpenGL renderer. As a consequence, mipmapping is not supported. Force to use a core profile context, to get a higher version. Before: INFO: Renderer: opengl INFO: OpenGL version: 2.1 NVIDIA-14.0.32 355.11.11.10.10.143 WARN: Trilinear filtering disabled (OpenGL 3.0+ or ES 2.0+ required) After: INFO: Renderer: opengl DEBUG: Creating OpenGL Core Profile context INFO: OpenGL version: 4.1 NVIDIA-14.0.32 355.11.11.10.10.143 INFO: Trilinear filtering enabled when running with: scrcpy --verbosity=debug --render-driver=opengl Note: Since SDL_CreateRenderer() causes a fallback to OpenGL 2.1, the profile and version attributes have to be set and the context created _after_. PR #3895 <#3895> Signed-off-by: Romain Vimont <rom@rom1v.com>

rom1v · 2023-04-12T19:29:07Z

Merged 👍 Thank you.

I would like other people to test branch macos_opengl (with scrcpy --Vdebug --render-driver=opengl) on macOS before merging 😄

I've got a confirmation that it works as expected. 👍

rom1v reviewed Apr 5, 2023

View reviewed changes

Use OpenGL 3.2 on macOS when using --render-driver=opengl

079a35e

This way we get the best available OpenGL version on macOS. Explanation at Genymobile#3895

Use Core Profile context on macOS to get highest OpenGL version

67574b1

metayan closed this Apr 7, 2023

metayan deleted the get-better-opengl-version-on-macos branch April 7, 2023 13:33

metayan restored the get-better-opengl-version-on-macos branch April 7, 2023 14:30

metayan reopened this Apr 7, 2023

rom1v closed this Apr 12, 2023

metayan deleted the get-better-opengl-version-on-macos branch November 28, 2023 00:26

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