OpenGL supports a maximum of 8 simultaneous lights. If you want to have more than 8 lights in your world, you can associate your lights with a light group when you add them to the world. Vizard will only render the lights in the currently set light group. Each light group should not have more than 8 lights. An example would involve each room in the world having its own light group. When the viewpoint moves to another room, you would call setLightGroup to tell Vizard to enable the lights in the new room.