I've implemented ray-custom mesh collision detection through Bullet Physics library in OpenFrameworks. It shows how each building can be precisely separated from others by picking it with the mouse. During that it changes color, but could do other things, like show some additional information in 3d or on the GUI. Here it collides with the ray coming from the mouse, but can also be used to collide with the sun's vector, to imitate shadow's effect or other things. 3D models are made by me using Rhino.
Made by: Matas Ubarevicius
More info at: http://fucture.org
Music by: William J. Le Petomane - Epitaph for a Bearded Lady
Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)