BabylonJS - Transparent canvas

Canvas transparency lost when AA filter added on camera babylon.1.12

by Lio Vousk-prod.

HTML

<script src="http://vousk-prod.net/webgl/babyl/includes/babylon.1.12.js"></script>
<canvas id="canvas_3d"></canvas>

CSS

#canvas_3d {
    width : 600px; 
    height: 400px;
    border: 1px dashed white;
}

body {
    background: #236478;
}

JavaScript

(function(){
    var canvas = document.getElementById("canvas_3d");
    var engine = new BABYLON.Engine(canvas, true);
    scene = createScene(engine, canvas);     
    engine.runRenderLoop(function () {
            scene.render();
    });
})()


function createScene(engine, canvas) {
    var scene = new BABYLON.Scene(engine);

    //Here we tell our canvas to be transparent, so we can see the HTML background
    scene.clearColor = new BABYLON.Color4(0, 0, 0, 0);
       
    var lightHemi = new BABYLON.HemisphericLight("Hemi0", new BABYLON.Vector3(0, 10, 10), scene);
    var sun = new BABYLON.PointLight("Sunshine", new BABYLON.Vector3(20, 100, 2), scene);

    var box = BABYLON.Mesh.CreateBox("Box", 3, scene);
    box.position = new BABYLON.Vector3(4, 0, 0);
    var sphere = BABYLON.Mesh.CreateSphere("Sphere", 12, 3, scene);
    
    var targetCam = new BABYLON.Vector3(0, 0, 0);
    var orbitalCamera = new BABYLON.ArcRotateCamera("CameraOrbit", 1.57, 1.57, 10, targetCam, scene);
    scene.activeCamera.attachControl(canvas); 
 
    //Here is the faulty line, comment this one to see lovely transparency on canvas
    var fxaa = new BABYLON.FxaaPostProcess("fxaa", 1.0, orbitalCamera, BABYLON.Texture.TRILINEAR_SAMPLINGMODE, engine, true);    
    
    //the following line appears to be not needed to activate the AAf, you can de-comment or not, no effect on AAf nor transparency)
    //orbitalCamera.attachPostProcess(fxaa);
    
    return scene;
}