My other son had a practical training at Fraunhofer IGD. He wrote an OpenGL/C++ program in Windows where one views the earth rotating around the sun, thereby with its rotating moon, see picture below.
openglSunEM can either be called with or without textures using command line flag “-t”. Typing ESC stops the program.
The main geometric transformation is handled in
drawGLScene(): draw sun, draw earth, draw moon (which rotates around the earth, which in turn rotates around the sun). The speed of rotation can be increased or decreased with the arrow keys (
GDK_KEY_Down), one can zoom in or out (