Three.js Composer with RenderPass not working with MaskPass - three.js

Question

I can't get my RenderPass to write into a MaskPass. If I try doing the passes seperately (like only a TexturePass; or TexturePass + OutputPass) it works but I can't get my stencil buffer to work.
http://signaturefloors.dev.flooradvisor.com.au/productapp/floor_align.php
I just want to render the main "scene" 2 or 3 times into different stencils (which are then combined) but I can't even get a single MaskPass working if I also use a RenderPass. Mask + Texture pass seems to work, it's the RenderPass causing me issues.
Basically if I do MaskPass then RenderPass nothing is displayed. It SHOULD simply show me a masked plane.
// Composer
var texture1 = new THREE.TextureLoader().load( 'textures/2294472375_24a3b8ef46_o.jpg' );
var texturePass1 = new THREE.TexturePass( texture1 );
var clearMask = new THREE.ClearMaskPass();
var renderMask = new THREE.MaskPass( this.scene, this.camera );
var renderMaskInverse = new THREE.MaskPass( this.scene, this.camera );
renderMaskInverse.inverse = true;
var viewScene = new THREE.RenderPass( this.scene, this.camera );
// Composition pass
var outputPass = new THREE.ShaderPass( THREE.CopyShader );
outputPass.renderToScreen = true;
var renderTargetParameters = {
minFilter: THREE.LinearFilter,
magFilter: THREE.LinearFilter,
format: THREE.RGBFormat,
stencilBuffer: true
};
// Setup render target
var renderTarget = new THREE.WebGLRenderTarget( SCREEN_WIDTH, SCREEN_HEIGHT, renderTargetParameters );
this.composer = new THREE.EffectComposer(this.renderer, renderTarget);
var renderPass = new THREE.RenderPass(this.scene, this.camera);
//renderPass.renderToScreen = true;
this.composer.addPass( texturePass1 );
//this.composer.addPass( viewMask );
this.composer.addPass( renderMask );
this.composer.addPass( viewScene );
this.composer.addPass( clearMask );
this.composer.addPass( outputPass );

Answer 1

I've been looking for a solution to this for a day or so and fell over quite a few questions like yours. None with a useable answer, but I think I found a solution:
To enable masking of a RenderPass you need to set clear = false.
In your case:
var viewScene = new THREE.RenderPass( this.scene, this.camera );
viewscene.clear = false
This should do it! Here's a codepen: https://codepen.io/staus/pen/BJNNLq