How do I make charts in C language? do I need to learn X11/OpenGL or equivalents and advanced math knowledge either there is a lib to do it for me? the requeriments is be written in C,portable(UNIX/Windows) and allow use in proprietary software not open source.
By assuming doing by X11/OpenGL/Allegro etc how hard is this? I’ve never touched at such libraries.
Another question that come to my mind now: It’s possible do it by using Gtk+?
You could use GNU Plot. It has C API.