The Environment Project (Ocean Project)

Code for ACM TOG 2016 paper: Fast Weather Simulation for Inverse Procedural Design of 3D Urban Models by Garcia-Dorado et al.

Stellarium is a free GPL software which renders realistic skies in real time with OpenGL. It is available for Linux/Unix, Windows and macOS. With Stellarium, you really see what you can see with your eyes, binoculars or a small telescope.