A deep intervention to the raytracing algorithm is to use curved beams instead of straight lines, as it is usual for common raytracing algorithms. However, due to the features of virtual functions in C++ and the structure of the rendering code, this could be done without any change in the core raytracing algorithm. See this page for more information or its german equivalent .

The creation of the Einstein Ring can also be viewed in this animation (630KB!).

Another animation (200KB) shows the effect of some rotation of the membrane surface around the black hole.

MS-DOS Executable demonstrating the light bending near a black hole. You might need Borland's BGI drivers.

By numerically solving the equations of null geodesics (aka `light rays') in the background of the Schwarzschild Metric it is possible to simulate the view of a static observer in the strong gravitational field of a non-rotating black hole, down to the event horizon (where the Schwarzschild Metric breaks down). Even such criticial phenomena like the photon orbit can be visualized.