I wanted to how rendering a slippymap using OpenGL could be done. My primary goal was to create map viewer which can rotate, tilt and drag the map while loading the tiles to render asynchronously. It should more or less behave like leaflet/OpenLayers but allowing 3D.
You can see screenshots of the program at https://plus.google.com/103924407019744591826/posts/CLife8pvGoB
So far I only created a prototype, but it’s already nice to play around with it. The program was written in C++11 and is licensed under the MIT license.