We have to rerender the whole scene at least twice for every shadow casting light source. Imagine taking your framerate and dividing it by (4 + # of shadowcasting lights * 2). In other words, if you get 60fps right now, you would get 6 fps with just one or two shadowcasting lights.So we are going to just do one directional light for now. Maybe eventually we will allow multiple lights to cast shadows.
