three.js/examples/js/postprocessing/ShaderPass.js

( function () {

	class ShaderPass extends THREE.Pass {

		constructor( shader, textureID ) {

			super();
			this.textureID = textureID !== undefined ? textureID : 'tDiffuse';
			if ( shader instanceof THREE.ShaderMaterial ) {

				this.uniforms = shader.uniforms;
				this.material = shader;

			} else if ( shader ) {

				this.uniforms = THREE.UniformsUtils.clone( shader.uniforms );
				this.material = new THREE.ShaderMaterial( {
					defines: Object.assign( {}, shader.defines ),
					uniforms: this.uniforms,
					vertexShader: shader.vertexShader,
					fragmentShader: shader.fragmentShader
				} );

			}

			this.fsQuad = new THREE.FullScreenQuad( this.material );

		}
		render( renderer, writeBuffer, readBuffer /*, deltaTime, maskActive */ ) {

			if ( this.uniforms[ this.textureID ] ) {

				this.uniforms[ this.textureID ].value = readBuffer.texture;

			}

			this.fsQuad.material = this.material;
			if ( this.renderToScreen ) {

				renderer.setRenderTarget( null );
				this.fsQuad.render( renderer );

			} else {

				renderer.setRenderTarget( writeBuffer );
				// TODO: Avoid using autoClear properties, see https://github.com/mrdoob/three.js/pull/15571#issuecomment-465669600
				if ( this.clear ) renderer.clear( renderer.autoClearColor, renderer.autoClearDepth, renderer.autoClearStencil );
				this.fsQuad.render( renderer );

			}

		}
		dispose() {

			this.material.dispose();
			this.fsQuad.dispose();

		}

	}

	THREE.ShaderPass = ShaderPass;

} )();