They're not 'scripting functions' incidentally. It's important not to use the wrong terminology as it means a completely different thing. Scripting, in the context of game development, means the use of a secondary programming language embedded within your program to aid development. What you're actually referring to are more 'library functions'.

CrystalSpace is a 3D renderer - it provides 3D functionality and that's about it.
DarkBasic is a programming language - you learn its syntax and use its environment to create games, and it handles the low level details for you.
Something like SDL is a library - it too handles low level details, but you use it from within an existing programming language, like C++.

I think, you're possibly looking a little too far ahead. You should start with a simple API/library/engine and make simple games using whatever it provides for you. Browsing their websites usually gives you a good idea of whether it can make what you want. And from that game making experience, you'll learn what functionality you're missing, and know what to look for.