Geometry and math library feature requests thread

[unDEFER]

Hello, there!
I already have a lot of experience with D. I have written my own 
game engine for my game 
(https://sourceforge.net/projects/dizzy-omega/), but 
implementation of my collision detector is 2D and is ugly without 
good geometry library.
Now I have even two projects which very need in good geometry 
math library.
The first one is utility to fix color profile of any printer by 
print&scan special color test pages. The task which I can't to 
solve without good library is interpolating 3D-function only some 
random points of which are known.
The second project is also game project. It will use job done in 
Dizzy Omega, but game engine must be many improved to understand 
Collada format, animation engine and more universal collision 
detector in 3D. This game will open source but commercial which 
will distributed by "pay later" principle. Anyway I again need 
here some good geometry math library.

I want in this topic discuss which features must have such 
library to be universal and useful not only for my projects, but 
also for any your projects.

Thanks.