1. A computer-implemented method for rendering a shadow comprising: obtaining, in a computer, a three-dimensional (3D) scene comprising an object; detecting, via a sensor, an external physical light source that is external to the 3D scene; creating, in the computer, an artificial light source in the 3D scene that corresponds to the external physical light source; based on the artificial light source, casting, in the computer, a shadow of the object; rendering, via the computer, the 3D scene including the object and the shadow.