+public:
+ struct State {
+ glm::dvec3 pos;
+ glm::dvec3 vel;
+ State(
+ const glm::dvec3 &pos = glm::dvec3(0.0),
+ const glm::dvec3 &vel = glm::dvec3(0.0))
+ : pos(pos), vel(vel) { }
+ };
+ struct Derivative {
+ glm::dvec3 vel;
+ glm::dvec3 acc;
+ Derivative(
+ const glm::dvec3 &vel = glm::dvec3(0.0),
+ const glm::dvec3 &acc = glm::dvec3(0.0))
+ : vel(vel), acc(acc) { }
+ };
+