private void notifyRescale(ViewPort vp, float x, float y) {
        List<SceneProcessor> processors = vp.getProcessors();
        for (SceneProcessor proc : processors) {
            if (!proc.isInitialized()) {
                proc.initialize(this, vp);
            } else {
                proc.rescale(vp, x, y);
            }
        }
    }
Creates a new post ViewPort, to display the given camera's content.

<p>The view will be processed after the pre and main viewports.

@param viewName the desired viewport name
@param cam the Camera to use for rendering (alias created)
@return a new instance
jme3-core/src/main/java/com/jme3/renderer/RenderManager.java