A methodology for generating a drop shadow effect for objects in a graphical user interface is presented. A first object in a presentation space occludes the illumination from a simulated light source, and a dynamically determined drop shadow from the first object may partially occlude a second object....http://www.google.de/patents/US7439975?utm_source=gb-gplus-sharePatent US7439975 - Method and system for producing dynamically determined drop shadows in a three-dimensional graphical user interface
