three.js/src/renderers/WebGLMultipleRenderTargets.js

import { WebGLRenderTarget } from './WebGLRenderTarget.js';

class WebGLMultipleRenderTargets extends WebGLRenderTarget {

	constructor( width = 1, height = 1, count = 1, options = {} ) {

		super( width, height, options );

		this.isWebGLMultipleRenderTargets = true;

		const texture = this.texture;

		this.texture = [];

		for ( let i = 0; i < count; i ++ ) {

			this.texture[ i ] = texture.clone();
			this.texture[ i ].isRenderTargetTexture = true;

		}

	}

	setSize( width, height, depth = 1 ) {

		if ( this.width !== width || this.height !== height || this.depth !== depth ) {

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

			for ( let i = 0, il = this.texture.length; i < il; i ++ ) {

				this.texture[ i ].image.width = width;
				this.texture[ i ].image.height = height;
				this.texture[ i ].image.depth = depth;

			}

			this.dispose();

		}

		this.viewport.set( 0, 0, width, height );
		this.scissor.set( 0, 0, width, height );

		return this;

	}

	copy( source ) {

		this.dispose();

		this.width = source.width;
		this.height = source.height;
		this.depth = source.depth;

		this.scissor.copy( source.scissor );
		this.scissorTest = source.scissorTest;

		this.viewport.copy( source.viewport );

		this.depthBuffer = source.depthBuffer;
		this.stencilBuffer = source.stencilBuffer;

		if ( source.depthTexture !== null ) this.depthTexture = source.depthTexture.clone();

		this.texture.length = 0;

		for ( let i = 0, il = source.texture.length; i < il; i ++ ) {

			this.texture[ i ] = source.texture[ i ].clone();
			this.texture[ i ].isRenderTargetTexture = true;

		}

		return this;

	}

}

export { WebGLMultipleRenderTargets };