A quaternion simply is a vector of the form [s, x, y, z]T, where s relates to an angle θ, and [x, y, z]T = a defines a unit axis to rotate about.



Quaternions provide an alternative way to model rotations.  The mathematics of quaternions relies on hypercomplex numbers involving three imaginary numbers, which some find a bit exotic.
GLM supports quaternions:

#include "./include/glm/gtc/quaternion.hpp“

glm::quat q1 = glm::angleAxis(90.0f, glm::vec3(0.0f, 1.0f, 0.0f));

High