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

		let oldClearAlpha;

		if ( this.clearColor ) {

			renderer.getClearColor( this._oldClearColor );
			oldClearAlpha = renderer.getClearAlpha();

			renderer.setClearColor( this.clearColor, this.clearAlpha );

		}

		renderer.setRenderTarget( this.renderToScreen ? null : readBuffer );
		renderer.clear();

		if ( this.clearColor ) {

			renderer.setClearColor( this._oldClearColor, oldClearAlpha );

		}

	}
Performs the clear operation. This affects the current read or the default framebuffer.

@param {WebGLRenderer} renderer - The renderer.
@param {WebGLRenderTarget} writeBuffer - The write buffer. This buffer is intended as the rendering
destination for the pass.
@param {WebGLRenderTarget} readBuffer - The read buffer. The pass can access the result from the
previous pass from this buffer.
@param {number} deltaTime - The delta time in seconds.
@param {boolean} maskActive - Whether masking is active or not.