Re: [webkit-dev] Fall 2016 WebKit Contributors Meeting – Call for Speakers

Thu, 20 Oct 2016 10:20:19 -0700 

Hi John,

I hope to introduce attached WebGL OES_EGL_image_external Extension
proposal which is currently under discussion with WebGL working group
members.

I would like explain why it is needed and how it improves WebGL video
rendering performance to get feedbacks from WebKit Community.

Kind regards,
Byungseon Shin

--------------------------------
Software Architect

TV Web Service Team

LG Electronics Inc.


On Fri, Oct 7, 2016 at 6:44 AM Jonathan Davis <[email protected]> wrote:

> Hello WebKit Contributors,
>
> This is a reminder to please register for the WebKit Contributor’s Meeting
> at https://webkit.org/meeting to reserve your spot. The registration
> deadline has been extended to October 21st, but please don’t wait until
> then to register. Spots are reserved on a first-come first-serve basis.
>
> We’re also calling for speakers to propose talks this year. You can talk
> about things you are interested in working on, or areas of WebKit that need
> more attention.  If you don’t have a large topic, but still have something
> you want to discuss with the group, you can pitch a lightning talk.
> Lightning talks are limited 5-10 minutes to provide a blitz of quick,
> focused information.
>
> If you haven’t already submitted a proposal to me, please reply to this
> thread, or email me directly with your proposed topic.
>
> Thank you all,
> Jon Davis
> _______________________________________________
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>
Title: WebGL OES_EGL_image_external Extension Specification
WebGL
Khronos
 

WebGL OES_EGL_image_external Extension Specification

Name

OES_EGL_image_external

Contact

WebGL working group (public_webgl 'at' khronos.org)

Contributors

Byungseon Shin([email protected]), LG Electronics

Andrey Volykhin([email protected]), LG Electronics

Version

Last modified date: October 11, 2016
Revision: 3

Number

WebGL extension #k

Dependencies

Written against the WebGL API 1.0 specification.

Overview

This extension exposes the OES_EGL_image_external functionality to WebGL.

The following WebGL-specific behavioral changes apply:

  • Defines a new texture target TEXTURE_EXTERNAL_OES.
  • Provides a mechanism for binding HTMLVideoElement's EGLImage to external texture targets.

Consult the above extension for documentation, issues and new functions and enumerants.

When this extension is enabled:

  • Add support for OES_EGL_image_external texture binding of HTMLVideoElement.
  • When a fragment shader enables, requires, or warns OES_EGL_image_external with an #extension directive:
    • samplerExternalOES is a built-in type.
    • vec4 texture2D(samplerExternalOES sampler, vec2 coord) is a built-in function.
  • The GLSL macro OES_EGL_image_external is defined as 1.

IDL

[NoInterfaceObject]
interface OESEGLImageExternal {
    const GLenum TEXTURE_EXTERNAL_OES             = 0x8D65;
    const GLenum SAMPLER_EXTERNAL_OES             = 0x8D66;
    const GLenum TEXTURE_BINDING_EXTERNAL_OES     = 0x8D67;
    const GLenum REQUIRED_TEXTURE_IMAGE_UNITS_OES = 0x8D68;

    [RaisesException] void EGLImageTargetTexture2DOES(
        GLenum target, HTMLVideoElement video);
};

Sample Code

This a fragment shader that samples a video texture.

    #extension GL_OES_EGL_image_external : require
    precision mediump float;
    varying vec2 v_texCoord;

    //uniform sampler2D uSampler;
    uniform samplerExternalOES uSampler;

    void main(void) {
      gl_FragColor = texture2D(uSampler, v_texCoord);
    }

This shows application that renders video using proposed extension. 

    var videoElement = document.getElementById("video");
    var videoTexture = gl.createTexture();

    function update() {
        var ext = gl.getExtension('OES_EGL_image_external');
        if(ext !=== null){
            gl.bindTexture(ext.TEXTURE_EXTERNAL_OES, videoTexture);
            ext.EGLImageTargetTexture2DOES(ext.TEXTURE_EXTERNAL_OES, videoElement);
            gl.bindTexture(ext.TEXTURE_EXTERNAL_OES, null);
        }
    }

    function render() {
        gl.clearColor(0.0, 0.0, 1.0, 1.0);
        gl.clear(gl.COLOR_BUFFER_BIT);

        gl.bindBuffer(gl.ARRAY_BUFFER, squareVerticesBuffer);
        gl.vertexAttribPointer(vertexPositionAttribute, 3, gl.FLOAT, false, 0, 0);

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(ext.TEXTURE_EXTERNAL_OES, videoTexture);
        gl.uniform1i(gl.getUniformLocation(shaderProgram, "uSampler"), 0);

        gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
    }

Application renders each video frames into WebGL canvas based on game-loop pattern. 

    update();

    while (true) {
       processInput();
       render();
    }

Conformance Tests

Issues

Revision History

Revision 1, 2016/10/11

  • Initial revision.

Revision 2, 2016/10/11

  • Refine sample code.

Revision 3, 2016/10/11

  • Remove comment on WebGL API 2.0 dependency
  • Refine sample code as an implicit texture updating mode
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