Sets whether the sky box object is visible or not. By default it is not visible. The sky box will always appear behind all other 3D objects and will be drawn at the maximum visible view range, which is set with SetCameraRange. The sky box has an optional sun that will be drawn to match the current directional light direction, set with SetSunDirection. However it will not use the directional light color, so you can have the directional light as one color and the sky box sun as another color.
SetSkyBoxVisible( active )