rotate.cpp

mat3 Transform::rotate(const float degrees, const vec3& axis) {
    const float cosine = glm::cos(glm::radians(degrees));
    const float one_minus_cosine = 1.0f - cosine;
    const float sine = glm::sin(glm::radians(degrees));

    return glm::mat3(axis.x * axis.x * one_minus_cosine + cosine,
                     axis.x * axis.y * one_minus_cosine + axis.z * sine,
                     axis.x * axis.z * one_minus_cosine - axis.y * sine,

                     axis.y * axis.x * one_minus_cosine - axis.z * sine,
                     axis.y * axis.y * one_minus_cosine + cosine,
                     axis.y * axis.z * one_minus_cosine + axis.x * sine,

                     axis.z * axis.x * one_minus_cosine + axis.y * sine,
                     axis.z * axis.y * one_minus_cosine - axis.x * sine,
                     axis.z * axis.z * one_minus_cosine + cosine);
}