Graphene

Point — A point with 2 coordinates
Point3D — A point with 3 coordinates
Size — Size representation
Rectangle — Rectangular shape type
Quad — Four-vertex quadrilateral
Triangle — A triangle described by 3D points
Box — Axis-aligned bounding box
Sphere — A sphere
Frustum — A 3D field of view
SIMD vector — Low level floating point 4-sized vector
SIMD matrix — Low level floating point 4 by 4 matrix
Vectors — Vectors in 2, 3, and 4 dimensions
Matrix — 4x4 matrices
Euler — Euler angles
Quaternion — Quaternion operations
Plane — A plane in 3D space
Ray — A ray emitted from an origin in a given direction
Versioning information — Detemining the version of Graphene in use
GObject integration — Types for GObject properties and signals

Graphene is a library of data types commonly used to implement 2D-in-3D or full 3D canvases.

Graphene only contains math data types, like vectors and matrices; it does not deal with windowing system calls, event handling, drawing, or a full scene graph.