text: THREE.MaskPass = function ( scene, camera ) {
  
  	THREE.Pass.call( this );
  
  	this.scene = scene;
  	this.camera = camera;
  
  	this.clear = true;
  	this.needsSwap = false;
  
  	this.inverse = false;
  
  };
  
  THREE.MaskPass.prototype = Object.assign( Object.create( THREE.Pass.prototype ), {
  
  	constructor: THREE.MaskPass,
  
  	render: function ( renderer, writeBuffer, readBuffer /*, deltaTime, maskActive */ ) {
  
  		var context = renderer.getContext();
  		var state = renderer.state;
  
  		// don't update color or depth
  
  		state.buffers.color.setMask( false );
  		state.buffers.depth.setMask( false );
  
  		// lock buffers
  
  		state.buffers.color.setLocked( true );
  		state.buffers.depth.setLocked( true );
  
  		// set up stencil
  
  		var writeValue, clearValue;
  
  		if ( this.inverse ) {
  
  			writeValue = 0;
  			clearValue = 1;
  
  		} else {
  
  			writeValue = 1;
  			clearValue = 0;
  
  		}
  
  		state.buffers.stencil.setTest( true );
  		state.buffers.stencil.setOp( context.REPLACE, context.REPLACE, context.REPLACE );
  		state.buffers.stencil.setFunc( context.ALWAYS, writeValue, 0xffffffff );
  		state.buffers.stencil.setClear( clearValue );
  		state.buffers.stencil.setLocked( true );
  
  		// draw into the stencil buffer
  
  		renderer.setRenderTarget( readBuffer );
  		if ( this.clear ) renderer.clear();
  		renderer.render( this.scene, this.camera );
  
  		renderer.setRenderTarget( writeBuffer );
  		if ( this.clear ) renderer.clear();
  		renderer.render( this.scene, this.camera );
  
  		// unlock color and depth buffer for subsequent rendering
  
  		state.buffers.color.setLocked( false );
  		state.buffers.depth.setLocked( false );
  
  		// only render where stencil is set to 1
  
  		state.buffers.stencil.setLocked( false );
  		state.buffers.stencil.setFunc( context.EQUAL, 1, 0xffffffff ); // draw if == 1
  		state.buffers.stencil.setOp( context.KEEP, context.KEEP, context.KEEP );
  		state.buffers.stencil.setLocked( true );
  
  	}
  
  } );
  
  
  THREE.ClearMaskPass = function () {
  
  	THREE.Pass.call( this );
  
  	this.needsSwap = false;
  
  };
  
  THREE.ClearMaskPass.prototype = Object.create( THREE.Pass.prototype );
  
  Object.assign( THREE.ClearMaskPass.prototype, {
  
  	render: function ( renderer /*, writeBuffer, readBuffer, deltaTime, maskActive */ ) {
  
  		renderer.state.buffers.stencil.setLocked( false );
  		renderer.state.buffers.stencil.setTest( false );
  
  	}
  
  } );
  