I've spent the last year in graduate engineering studies at the University of Virginia. A ray tracing course that I took this semester, sparked my interest in global lighting effects both with ray tracing and more importantly, real time rendering for gaming. One of my favorite effects has always been the effect rain drops make when viewed from behind a windshield or other wet glass material. So I decided to try to reproduce it on my own. The basic idea was to draw a single quad at the camera whose surface properties (BRDF) would model the droplet effect instead of the geometry. This was done by refracting rays that intersected with the circular droplet bases and then refracting them as if they had gone through a hemispherical droplet of water and out to the scene.

The realtime version of this effect were achieved by rendering the scene first to the front side of a cube map texture and accessing that texture from inside a shader to get the approximate color for the refracted ray. My sf2 engine was used to build the OpenGL scene's, shaders and application

- Ray traced image using pbrt. Full size took 24 hours of computation time	- Imaged base lighting effect
- Real time droplet effect