global_shader_variables/buffer_size set too high in new Compatibility project

[lostminds]

Godot version

4.2.rc2

System information

macOS 14.1

Issue description

Creating a new Compatibility project the default setting for rendering/limits/global_shader_variables/buffer_size is set to 65536, but apparently this is too high for Compatibility renderer limits, because you get a warning when running:

W 0:00:00:0093   MaterialStorage: Project setting "rendering/limits/global_shader_variables/buffer_size" exceeds maximum uniform buffer size of: 16384
  <C++ Source>   drivers/gles3/storage/material_storage.cpp:1114 @ MaterialStorage()

Steps to reproduce

Create a new blank Compatibility project, with an empty scene and run it and see the warning

Minimal reproduction project

Just create a new project from the project manager as I think the issue is the default value for new Compatibility projects.

[jsjtxietian]

Yes, the max_uniform_buffer_size is read from GL using glGetInteger64v(GL_MAX_UNIFORM_BLOCK_SIZE, &max_uniform_buffer_size);, if it's smaller than the project setting's value (default is 65536) it will give a warning. Is there anything we can do other than just ignore the warning ?

[Jakub-Doucek]

In version: 4.2.1 the default value is 16384
But on iOS device I'm getting the warning anyway
USER WARNING: Project setting "rendering/limits/global_shader_variables/buffer_size" exceeds maximum uniform buffer size of: 16384

The warning is probably ok, because the limit is for some reason really small. And that's what I see as the main problem. 3D models need to have a very small polycount. The same device has no problem with the Vulkan renderer.

[jsjtxietian]

Can we define "rendering/limits/global_shader_variables/buffer_size" based on OS and rendering method? If so we can give it seperate definition.

[Jakub-Doucek]

From my user-usage perspective, I don't think a split limit per platform would be an advantage. The project needs to be tailored to the lowest value to work properly. So the lowest value can be common to all platforms.

However, it seems that the core of the problem is that this limit exists at all. For mobile devices, the limit is very restrictive. It is not possible to render even a relatively simple low-poly 3D object.

I found a related problem here: #55674

Where @clayjohn suggests:

we could automatically split the uniforms up into multiple UBOs internally, or use a SSBO internally

That's the solution I'd like. I haven't found any open issue for it.

[jsjtxietian]

split the uniforms up into multiple UBOs internally, or use a SSBO internally

Yeah that includes more work, and potentially less performant if SSBO is used.

[clayjohn]

SSBOs aren't supported in OpenGL 3.3, nor can we use multiple UBOs for the global buffer. So we are kinda stuck with the low limit for compatibility devices.

[Jakub-Doucek]

My understanding of these low-level rendering things is limited, but I don't believe it can't be done. Especially since it works in version 3.5. So I see it as a regression bug.

Tested on: iPhone 13 Pro Max - iOS 17.1.2 (21B101)

I created a simple project with a 3D scene and imported two models (in Godot 4 they are in AssetLib)

Godot 3.5

iPhone screenshot:

log:

*********** main.m
running app main
Path: /var/containers/Bundle/Application/C6A87A44-043A-4569-BADF-F11E52848509/render_test.app
godot_iphone /var/containers/Bundle/Application/C6A87A44-043A-4569-BADF-F11E52848509/render_test.app/render_test
cwd /private/var/containers/Bundle/Application/C6A87A44-043A-4569-BADF-F11E52848509/render_test.app
os created
setting data dir to /var/mobile/Containers/Data/Application/0B717A00-97AA-42CF-892E-64DB3D6894DF/Documents from /var/mobile/Containers/Data/Application/0B717A00-97AA-42CF-892E-64DB3D6894DF/Documents
setup 0
Setting up an OpenGL ES 3.0 context. Based on Project Settings "rendering/quality/driver/driver_name"
failed to make complete framebuffer object 8cd6
Failed to create frame buffer!
******** setting up keyboard input view
******** adding observer for keyboard show/hide
start animation!
ERROR: AudioOutputUnitStart failed, code: -50
   at: start (drivers/coreaudio/audio_driver_coreaudio.cpp:249) - AudioOutputUnitStart failed, code: -50
Godot Engine v3.5.stable.official.991bb6ac7 - https://godotengine.org
OpenGL ES 3.0 Renderer: Apple A15 GPU
Async. shader compilation: OFF
ERROR: AudioOutputUnitStart failed, code: -50
   at: start (drivers/coreaudio/audio_driver_coreaudio.cpp:249) - AudioOutputUnitStart failed, code: -50
Godot Engine v3.5.stable.official.991bb6ac7 - https://godotengine.org
OpenGL ES 3.0 Renderer: Apple A15 GPU
Async. shader compilation: OFF
 

******** stop animation!
Audio interruption began
start animation!
******** stop animation!
Audio interruption began

Godot 4.2.1

iPhone screenshot:

log:

USER ERROR: AudioOutputUnitStart failed, code: -50
   at: start (drivers/coreaudio/audio_driver_coreaudio.cpp:251)
USER ERROR: AudioOutputUnitStart failed, code: -50
   at: start (drivers/coreaudio/audio_driver_coreaudio.cpp:251)
Godot Engine v4.2.1.stable.official.b09f793f5 - https://godotengine.org
Godot Engine v4.2.1.stable.official.b09f793f5 - https://godotengine.org
Setting up an OpenGL ES 3.0 context.
USER WARNING: Project setting "rendering/limits/global_shader_variables/buffer_size" exceeds maximum uniform buffer size of: 16384
   at: MaterialStorage (drivers/gles3/storage/material_storage.cpp:1114)
USER WARNING: Project setting "rendering/limits/global_shader_variables/buffer_size" exceeds maximum uniform buffer size of: 16384
   at: MaterialStorage (drivers/gles3/storage/material_storage.cpp:1 114)
fopen failed for data file: errno = 2 (No such file or directory)
Errors found! Invalidating cache...
fopen failed for data file: errno = 2 (No such file or directory)
Errors found! Invalidating cache...
OpenGL API OpenGL ES 3.0 Metal - 99 - Compatibility - Using Device: Apple Inc. - Apple A15 GPU
OpenGL API OpenGL ES 3.0 Metal - 99 - Compatibility - Using Device: Apple Inc. - Apple A15 GPU
 

USER WARNING: Icon not supported by this display server.
   at: set_icon (servers/display_server.cpp:577)
USER WARNING: Icon not supported by this display server.
   at: set_icon (servers/display_server.cpp:577)
fopen failed for data file: errno = 2 (No such file or directory)
Errors found! Invalidating cache...
DrawView: 506 error
Audio interruption began
Audio interruption began

[Jakub-Doucek]

I apologize for the misunderstanding. I have investigated the problem further and found that it is probably not related to the exceeds maximum uniform buffer size warning at all.
It helped to reduce the polycount and I saw the warning, so I thought it was because of that.
But it was fixed probably just because I re-exported the model without animations.

The model doesn't seem to render if it has bones attached. So it's an unrelated issue. It still occurs in 4.3.dev1 version.

Edit: I've created a separate bug report: #86830

[clayjohn]

@Jakub-Doucek Indeed, 3.5 doesn't support global shader uniforms, and you don't appear to be using them in your project anyway, so your issue isn't related at all.

[lostminds]

I just tested this in 4.2.1 to see if it was still an issue and when creating a new Compatibility project and running it I'm no longer getting the warning. However, when checking the project settings rendering/limits/global_shader_variables/buffer_size is still 65536, so the default hasn't changed.

Can anyone confirm if this mean the issue is now solved so I can close this issue (that the Compatibility renderer now supports this buffer size?) or is there some other change that just causes the warning not to show even if the limit is still there?

[Calinou]

I think you got this warning 4.2.rc2 because it was using ANGLE by default on macOS, but this is no longer the case. If you edit project settings to use the opengl3_angle rendering driver (not rendering method), you will probably see that warning again.

[lostminds]

If you edit project settings to use the opengl3_angle rendering driver (not rendering method), you will probably see that warning again.

I see, that may be the case. However, it seems I can't use the Angle OpenGL drivers anymore (They used to work). Changing the project setting to used Angle and restarting I get the following error and get switched back to native OpenGL again:

_get_gldisplay_id: Condition "eglGetError() != 0x3000" is true. Returning: -1
  <C++ Source>   drivers/egl/egl_manager.cpp:63 @ _get_gldisplay_id()
 DisplayServerMacOS: Your video card drivers seem not to support the required Metal version, switching to native OpenGL.
  <C++ Source>   platform/macos/display_server_macos.mm:4529 @ DisplayServerMacOS()

Not sure what's going on there, but it seems unlikely the graphics card doesn't support the required Metal version (unless it's some old outdated Metal version) as it's quite a new M2 mac. And I did use the angle driver briefly back when that was the default on mac.