code: function init() {
    /**
     * Called on each animation frame
     */
    function animate() {
      render();
  
      // request new frame
      requestAnimationFrame(function() {
        animate();
      });
    }
  
    // renderers
    initRenderer3D(r0);
    initRenderer2D(r1);
    initRenderer2D(r2);
    initRenderer2D(r3);
  
    // start rendering loop
    animate();
  }
docs: Init the quadview