public void setPaperColor(ColorRGBA paperColor) {
        this.paperColor = paperColor;
        if (material != null) {
            material.setColor("PaperColor", paperColor);
        }
    }
Sets color used as background

@param paperColor the desired color (alias created, default=(1,1,1,1))
jme3-effects/src/main/java/com/jme3/post/filters/CrossHatchFilter.java