Aff3 is a 3x3 affine transformation matrix in row major order, where the bottom row is implicitly [0 0 1].

Aff4 is a 4x4 affine transformation matrix in row major order, where the bottom row is implicitly [0 0 0 1].

Mat3 is a 3x3 matrix in row major order.

Mat4 is a 4x4 matrix in row major order.

Vec2 is a 2-element vector.

Vec3 is a 3-element vector.

Vec4 is a 4-element vector.