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+/* Copyright (c) 2012 Patrick Ruoff
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ */
+
+#pragma once
+#include <cmath>
+
+class Quat {
+private:
+ static constexpr double pi = 3.141592653;
+ static constexpr double r2d = 180./pi;
+ double a,b,c,d; // quaternion coefficients
+public:
+ Quat() : a(1.0),b(0.0),c(0.0),d(0.0) {}
+ Quat(double yaw, double pitch, double roll) { from_euler_rads(yaw, pitch, roll); }
+ Quat(double a, double b, double c, double d) : a(a),b(b),c(c),d(d) {}
+
+ Quat inv(){
+ return Quat(a,-b,-c, -d);
+ }
+
+ // conversions
+ // see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles
+ void from_euler_rads(double yaw, double pitch, double roll)
+ {
+
+ double sin_phi = sin(roll/2.0);
+ double cos_phi = cos(roll/2.0);
+ double sin_the = sin(pitch/2.0);
+ double cos_the = cos(pitch/2.0);
+ double sin_psi = sin(yaw/2.0);
+ double cos_psi = cos(yaw/2.0);
+
+ a = cos_phi*cos_the*cos_psi + sin_phi*sin_the*sin_psi;
+ b = sin_phi*cos_the*cos_psi - cos_phi*sin_the*sin_psi;
+ c = cos_phi*sin_the*cos_psi + sin_phi*cos_the*sin_psi;
+ d = cos_phi*cos_the*sin_psi - sin_phi*sin_the*cos_psi;
+ }
+
+ void to_euler_rads(double& yaw, double& pitch, double& roll) const
+ {
+ roll = atan2(2.0*(a*b + c*d), 1.0 - 2.0*(b*b + c*c));
+ pitch = asin(2.0*(a*c - b*d));
+ yaw = atan2(2.0*(a*d + b*c), 1.0 - 2.0*(c*c + d*d));
+ }
+
+ void to_euler_degrees(double& yaw, double& pitch, double& roll) const
+ {
+ to_euler_rads(yaw, pitch, roll);
+ yaw *= r2d;
+ pitch *= r2d;
+ roll *= r2d;
+ }
+
+ const Quat operator*(const Quat& B) const
+ {
+ const Quat& A = *this;
+ return Quat(A.a*B.a - A.b*B.b - A.c*B.c - A.d*B.d, // quaternion multiplication
+ A.a*B.b + A.b*B.a + A.c*B.d - A.d*B.c,
+ A.a*B.c - A.b*B.d + A.c*B.a + A.d*B.b,
+ A.a*B.d + A.b*B.c - A.c*B.b + A.d*B.a);
+ }
+};