DataTextureLoader: provide alternative function for parsing explicit databuffer.

[sciecode]

Parsing a simple buffer with a similar API as the common DataTexureLoader.load is not standardly supported, however it would seem logical for allowing features like drag and drop and easy server-side loading of DataTextures.

An example of the current workflow for doing such can be observed in webgl_materials_matcap.
jade.exr - open example file for testing - credits to Michael Harmon.

three.js/examples/webgl_materials_matcap.html

Lines 178 to 195 in 696d783

	var contents = event.target.result;
	var loader = new EXRLoader();
	var texData = loader.parse( contents );
	var texture = new THREE.DataTexture();
	texture.image.width = texData.width;
	texture.image.height = texData.height;
	texture.image.data = texData.data;
	texture.format = texData.format;
	texture.type = texData.type;
	texture.generateMipmaps = false;
	texture.magFilter = THREE.LinearFilter;
	texture.minFilter = THREE.LinearFilter;

In order to allow drag-and-drop ( or similar instant parsing ) we are required to manually invoke the specific loader.parser and replicate the onLoad events of both DataTextureLoader and the loader itself.

Wouldn't it make sense to supply a simpler built-in function for such workflow? Or, perhaps, it is expected of the loader to always provide a structured object that can be immediately used, bypassing this:

three.js/src/loaders/DataTextureLoader.js

Lines 38 to 85 in 696d783

	if ( texData.image !== undefined ) {
	texture.image = texData.image;
	} else if ( texData.data !== undefined ) {
	texture.image.width = texData.width;
	texture.image.height = texData.height;
	texture.image.data = texData.data;
	}
	texture.wrapS = texData.wrapS !== undefined ? texData.wrapS : ClampToEdgeWrapping;
	texture.wrapT = texData.wrapT !== undefined ? texData.wrapT : ClampToEdgeWrapping;
	texture.magFilter = texData.magFilter !== undefined ? texData.magFilter : LinearFilter;
	texture.minFilter = texData.minFilter !== undefined ? texData.minFilter : LinearFilter;
	texture.anisotropy = texData.anisotropy !== undefined ? texData.anisotropy : 1;
	if ( texData.format !== undefined ) {
	texture.format = texData.format;
	}
	if ( texData.type !== undefined ) {
	texture.type = texData.type;
	}
	if ( texData.mipmaps !== undefined ) {
	texture.mipmaps = texData.mipmaps;
	texture.minFilter = LinearMipmapLinearFilter; // presumably...
	}
	if ( texData.mipmapCount === 1 ) {
	texture.minFilter = LinearFilter;
	}
	texture.needsUpdate = true;
	if ( onLoad ) onLoad( texture, texData );

If so, how would you suggest structuring such API? Would it make sense to supply a similar interface to other loaders?

Credits to @WestLangley for the idea, I'm replicating and discussing it.