Как рисовать тень используя направленный источник света(прожектор)

We saw at the TIP 109 How to draw Cast Shadow using PARALLEL source light. Today let's see more about DIVERGING source light. You are free to use any of these 2 techniques. Let's consider the volumes in the videos are something you could hold in your hand. Basically, I consider that the Parallel source light come from a (huge) wide source of light such as the sun. The Diverging source light would fit better for small lights such as projectors. Note that it's all about scale.