To understand why I need to do that @sebavan, you can check this previous topic explaining what I am trying to achieve: Slowly showing new frame
When we check the layer code: Babylon.js/layer.ts at master · BabylonJS/Babylon.js · GitHub we can see that using onAfterRenderObservable we can managed to wait for the shader to be ready: https://www.babylonjs-playground.com/#DEYAQ5#99