KorGE uses KorMA as geometry mathematical library.
This library provides 2D Vectors, Rectangles, Matrix2D, ScaleMode, Size, Position… It provides interpolation facilities. Along as numeric functions. Has Bezier curves calculation primitives.
It has a VectorPath with mixed straight + curved lines that can be triangulated. You can do path finding in triangulated surfaces using TRA* algorithm. You can calculate union, intersection, substraction, xor o collision among shapes. It also provides a BinPacker for allocating rectangles in a surface (useful for atlas generation).
KorMA doesn’t have any external dependency. So you can use it alone.