Accessing WebGL types in a worker?

[greggman]

I'm probably just missing this somewhere but, I have some semi-generic WebGL code that needs to check if an object is WebGLTexture or a WebGLRenderbuffer. For the last several years I've had code like this

  isTexture = object instanceOf WebGLTexture;

But now I'm trying to run this code in a worker and AFAICT WebGLTexture does not exist inside a worker even though WebGL itself is running via OffscreenCanvas.

• Is this a known issue?
• Will the WebGL types be exposed inside a worker?
• Are they exposed somewhere not the global object?

As it is a few workarounds which seem unclean (some wishy washy feeling I know but ...)

1. call gl.isTexture which requires a WebGLTexture but throws if it's not. Seems pretty heavy to generate an exception just to check this stuff. In other words

    function isTexture(gl, obj) {
      let result = false;
      try {
        result = gl.isTexture(obj);
      } catch (e) {
      }
      return result;
    }
   

2. call representative = gl.createTexture() somewhere then use objectInQuestion instanceOf representative.constructor. ugh but it works and at least it's fast and doesn't generate garbage every check as 1 above does but it does generate a bogus object.

3. ???

[kainino0x]

This sounds like an oversight to me, but I haven't worked on OffscreenCanvas myself. In Chrome, it looks like it's just a matter of adding Exposed(Worker ExperimentalCanvasFeatures) to WebGLTexture and the rest of the WebGL interface objects (we already have it for WebGL(2)RenderingContext).

cc @junov

[foolip]

This will have to be fixed in the specs as well. As of whatwg/webidl#423 [Exposed] is mandatory, relevant change deep in https://heycam.github.io/webidl/#idl-interfaces: "Non-callback interfaces which are not annotated with a [NoInterfaceObject] extended attribute, and callback interfaces which declare constants must be annotated with an [Exposed] extended attribute."

[kenrussell]

Chromium's implementation has been fixed to expose these interfaces on workers as of https://chromium-review.googlesource.com/1142292 .