UpdatableTexture.js

function UpdatableTexture( format, type, mapping, wrapS, wrapT, magFilter, minFilter, anisotropy, encoding ) {

	THREE.Texture.call( this, null, mapping, wrapS, wrapT, magFilter, minFilter, format, type, anisotropy, encoding );

	var canvas = document.createElement('canvas');
	canvas.width = 1;
	canvas.height = 1;
	var ctx = canvas.getContext('2d');
	var imageData = ctx.createImageData(1, 1);

	this.image = imageData;

	this.magFilter = magFilter !== undefined ? magFilter : THREE.LinearFilter;
	this.minFilter = minFilter !== undefined ? minFilter : THREE.LinearMipMapLinearFilter;

	this.generateMipmaps = true;
	this.flipY = true;
	this.unpackAlignment = 1;
	this.needsUpdate = true;

}

UpdatableTexture.prototype = Object.create( THREE.Texture.prototype );
UpdatableTexture.prototype.constructor = UpdatableTexture;

UpdatableTexture.prototype.isUpdatableTexture = true;

UpdatableTexture.prototype.setRenderer = function( renderer ) {

	this.renderer = renderer;
	this.gl = this.renderer.getContext()
	this.utils = THREE.WebGLUtils(this.gl, this.renderer.extensions)

}

UpdatableTexture.prototype.setSize = function( width, height ) {

	if( width === this.width && height === this.height ) return;

	var textureProperties = this.renderer.properties.get( this );
	if( !textureProperties.__webglTexture ) return;

	this.width = width;
	this.height = height;

	var activeTexture = this.gl.getParameter( this.gl.TEXTURE_BINDING_2D );
	this.gl.bindTexture( this.gl.TEXTURE_2D, textureProperties.__webglTexture );
	if( !textureProperties.__webglTexture ) this.width = null;
	this.gl.texImage2D(
		this.gl.TEXTURE_2D,
		0,
		this.utils.convert( this.format ),
		width,
		height,
		0,
		this.utils.convert( this.format ),
		this.utils.convert( this.type ),
		null
	);
	this.gl.bindTexture( this.gl.TEXTURE_2D, activeTexture );

}

UpdatableTexture.prototype.update = function( src, x, y ) {

	var textureProperties = this.renderer.properties.get( this );
	if( !textureProperties.__webglTexture ) return;

	var activeTexture = this.gl.getParameter( this.gl.TEXTURE_BINDING_2D );
	this.gl.bindTexture( this.gl.TEXTURE_2D, textureProperties.__webglTexture );
	this.gl.texSubImage2D(
		this.gl.TEXTURE_2D,
		0,
		x,
		this.height - y - src.height,
		this.utils.convert( this.format ),
		this.utils.convert( this.type ),
		src
	);
	this.gl.generateMipmap( this.gl.TEXTURE_2D );
	this.gl.bindTexture( this.gl.TEXTURE_2D, activeTexture );

}