1 files changed, 48 insertions, 0 deletions
diff --git a/facetracknoir/rotation.cpp b/facetracknoir/rotation.cpp
new file mode 100644
index 00000000..1c89d775
--- /dev/null
+++ b/facetracknoir/rotation.cpp
@@ -0,0 +1,48 @@
+/* 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.
+ */
+
+#include "rotation.h"
+
+#include <cmath>
+
+// ----------------------------------------------------------------------------
+Rotation Rotation::inv()
+{
+	return Rotation(a,-b,-c,-d);
+}
+
+// conversions
+// see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles
+void Rotation::fromEuler(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 Rotation::toEuler(double& yaw, double& pitch, double& roll)
+{
+	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));
+}
+
+Rotation operator*(const Rotation& A, const Rotation& B)
+{
+	return Rotation(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);
+}
+\ No newline at end of file