Add webgl2 parameter (default:false) to WebGLRenderer parameters.

[mckaydavis]

I humbly submit this pull request that adds a webgl2 boolean parameter to the WebGLRenderer constructor. When set to true (default is false) it will attempt to instance a WebGL2RenderingContext.

I've read through issue #9965 and understand the want to keep WebGL 2.0 features in WebGL2Renderer.

In my use case, I only need the standard WebGL 1.0 context and corresponding three.js interface -- except for a few WebGL 2.0 calls outside three.js.

This PR would allow using the well-tested three.js interface while allowing for experimentation w/ WebGL 2.0.

[mrdoob]

Do you mind sharing a example code of how to use it? I guess you write your own shaders?

[mckaydavis]

@mrdoob unfortunately I can't share the code as it's for a private project (and I'm too lazy to mock-up one).

In the meantime I've realized the same result can be achieved in the existing codebase by passing the context parameter already initialized w/ a WebGL2RenderingContext outside three.js. The examples/ directory actually has such a case:

three.js/examples/webgl_depth_texture.html

Line 112 in e8ad809

var canvas = document.querySelector('canvas');

...therefore I'm fine to reject the pull request as it's redundant.

[mrdoob]

In the meantime I've realized the same result can be achieved in the existing codebase by passing the context parameter already initialized w/ a WebGL2RenderingContext outside three.js.

Yeah, I realised that too. I was going to suggest that.