Create texture from canvas

[lucadalli]

At the moment, creating a texture from canvas is possible by passing the data URL or an object URL to the createTexture method. For larger textures this adds quite a bit of overhead (~100ms).
THREE natively supports creating a texture from canvas via CanvasTexture. Is this something we can leverage to allow createTexture to accept canvas input?

[samaneh-kazemi]

Hi, looking at how CanvasTexture is implemented and the documentation, it should have similar overhead since it calls Texture constructor. This is also stated in their doc you shared. The 'createTexture' is using 'Texture' so I'm not sure if even if we support CanvasTexture it helps with the overhead.

CanvasTexture code

		super( canvas, mapping, wrapS, wrapT, magFilter, minFilter, format, type, anisotropy );

		this.needsUpdate = true;

[elalish]

I believe @lucadalli is making that point that Three's Texture object can take a canvas element and handle it more efficiently than a URL. It's possible we are artificially restricting ourselves. @lucadalli would you be interesting in trying a PR for this?

[lucadalli]

@elalish I don't mind giving it a go.