Is it possible to enable GLES 3.1 features?

[杨飞]

Hi everyone.

I've asked a similar question in chromium-dev, then I realized here might be the better place to ask.

I'm trying to hack Blink (in Chromium) to embed a native 3D rendering engine behind Chromium. In addtion, I want it to shared the same context as the WebGL2 context of a Canvas.

The problem is that OpenGL ES 3.1 features are disabled by default. For example, when I try to call GLES2Interface::CreateShader with GL_COMPUTE_SHADER, I got "GL_INVALID_ENUM: OpenGL ES 3.1 Required". That basically means, the features of GLES2Interface are the same as those already exposed as WebGL. 

I therefore wonder, is there an easy way to enable the OpenGL ES 3.1 features during Chromium building? Maybe using some gn args? 

Here is my project (without involving Chromium): https://github.com/fynv/Three.V8

The whole purpose of the attempt is to try to utilize the native OpenGL features which are not exposed through WebGL. But it looks like, if the GLES 3.1 features are enabled in 

GLES2Interface, they will also be exposed to WebGL. Is that the case?

Thanks

Fei

[Ken Russell]

Hi Fei,

Several years ago there was much discussion about which direction to take web graphics standards - either continue to extend WebGL toward OpenGL ES 3.1/3.2, or pursue the new family of low-level explicit graphics APIs (D3D12/Metal/Vulkan). After much investigation it was decided to leave the legacy behind and pursue a new standard, WebGPU. There is a tremendous amount of cross-industry momentum behind WebGPU; the first version, and implementations, will ship later this year.

I recommend you abandon the course of trying to get an OpenGL ES 3.1 JavaScript binding in Chromium, and instead see whether you can achieve what you want using the existing WebGPU implementation in Chromium, as well as Dawn, Chromium's native implementation of the API.

https://gpuweb.github.io/gpuweb/

https://gpuweb.github.io/gpuweb/explainer/

https://dawn.googlesource.com/dawn/

Best,

-Ken

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[杨飞]

Hi Ken,

Thanks for answering.

I haven't given up on this yet. But there's something really difficult for me to get through.

To make it clear, I'm not attempting to bring back the dropped "WebGL2 compute" feature. 

Instead, I just want to enable an underlying GLES3.1 context (powered by ANGLE), so that I can use it in my own fork of Chromium, internally in C++ code.

Therefore, it won't envolve exposing any addition APIs to JavaScript. It's just about the context creation.

I made some progress by doing to following hacks:

* In gpu/command_buffer/client/implementation_base.cc

Forcing the capabilites to version 3.1 by:

In constructor ImplementationBase::ImplementationBase():

if (capabilities_.major_version == 3)
{
      capabilities_.minor_version = 1;
      capabilities_.max_shader_storage_buffer_bindings = 32768;
 }

* In gpu/command_buffer/services/service_utils.cc

In GenerateGLContextAttribs():

Changing "client_minor_es_version" from 0 to 1.

Currently, I'm able to compile a compute shader, creating and binding SSBOs, 

but it still crashes when I call GLES2Interface::DispatchCompute() to launch a compute shader. (STATUS_ACCESS_VIOLATION)

I feel I still hadn't found the correct places where the GLES context creation is happening, where Blink tells ANGLE which GLES version to use.

I'll really appreciate you if you point me to the correct place to look at. The source code is just too Huge.

Thanks!!

Fei

[杨飞]

Hi Ken,

I've just hacked through it!! 

Turns out that things just got a little bit complicated after the "ES31ForTesting" context was added.

The final list of hacks:

* In gpu/command_buffer/services/gl_utils.cc

In PopulateNumericCapabilities():

Skip IsES31ForTestingContext check. Always set "minor_version" to 1

* In gpu/command_buffer/services/service_utils.cc

In GenerateGLContextAttribs():

Changing "client_minor_es_version" from 0 to 1.

* In gpu/command_buffer/services/gles2_cmd_decoder.cc

In GetCapabilities():

Changing " minor_version " from 0 to 1.

* In gpu/command_buffer/services/gles2_cmd_decoder_passthrough_handlers.cc

and gpu/command_buffer/services/gles2_cmd_decoder_passthrough_handlers_autogen.cc 

Skip all "if(!IsES31ForTestingContext ())" checks.

Commented out all of them because not sure how to run "build_cmd_buffer_lib.py".

Thanks.

Fei