Casting shadows from a layer that has been turned off

Even if a layer is invisible, sometimes it is important to have that layer cast a shadow. Create this scenario by choosing a new Cast Shadows option called Only. Choosing Only turns off the layer but leaves the shadow it casts. Use this in conjunction with the Light Transmission option to project the colors from the invisible layer onto a visible one. To choose Only, click the current underlined Cast Shadow option until Only displays.