For the veter-project I was searching for the simple, cross-platform
and complete example how to download map tiles from openstreetmap.org
and visualize them using C++. The closest thing I found was the Qt-
based demo . Since I am not using Qt in my project I decide to
create my own example with SDL. I think what comes out could be useful
for someone else trying to write similar application so I decide to
announce this example here. The source code and brief description is
available here .
In this application map tiles are downloaded from openstreetmap.org
For the visualization, this application uses OpenGL with texture
mapped on the simple quad. Texture is updated every time the new tile
is completely downloaded. Simple caching mechanism is implemented by
saving tiles on the hard disk. This visualization technique could be
used to integrate map visualization into more sophisticated 3D scene.
In addition, this example illustrates how to use advanced features of
the CURL library  to handle multiple http requests simultaneously.