Director
Time line hooks
A CAAT.Director object will by default clean in a per frame basis the animations background.
Despite a Director object is an Actor, it will surpass the effects of calling either setFillStle( style ) or setBackgroundImage( image ) methods. The Director instance clears the background by calling rendering context's clearRect when using a Canvas renderer and gl.clear(this.gl.COLOR_BUFFER_BIT | this.gl.DEPTH_BUFFER_BIT) if webGL is enabled.
It will be a common error and performance sinker to let a canvas based director to clean the background once and doing it again in the scene.
To avoid this you could call director's setClear(false).
It will be more proper to do it as follows:
scene.activated= function() { director.setClear(false); };
The reason is that the entering scene may not cover the whole director's area ( i.e. the scene enters rotating or scaling) and if set directly director.setClear(false) will prevent to clear the background, thus creating visual artifacts. With this code, as soon as the scene is activated the director won't clear its background anymore.