A black hole is the most weird object in the universe. An object that passes behind it appears strongly distorted because of the black hole's influence on light propagation. Turn your smart phone or tablet into a general relativistic simulator and move the black hole around.
The visualization is based on Einstein's general theory of relativity for a Schwarzschild black hole. The object is represented by an image that is put on a canvas behind the black hole. The distance between the canvas and the black hole, as well as the distance between the black hole and the observer, can be modified. Of course, the black hole mass can also be changed.
For the screenshots, NASA's "Blue Marble" photograph of Apollo 17 and the Milky Way panorama by ESO/S.Brunier were taken.
Your smart phone or tablet has to support 32 bit floating point operations on the graphics card, otherwise, there will be artifacts or nothing will be shown.
Please note that you can use only images that fit into the GPU texture memory of your device.
Black hole can be moved also with the gravity sensor. Set a moving factor within "Settings" (1000 is a good choice) and then just move your smartphone or tablet.