git-svn-id: https://reactphysics3d.googlecode.com/svn/trunk@97 92aac97c-a6ce-11dd-a772-7fcde58d38e6

sources/reactphysics3d/mathematics/Quaternion.cpp

@@ -54,6 +54,35 @@ Quaternion::~Quaternion() {
 
 }
 
+// Compute the rotation angle (in radians) and the 3D rotation axis
+// This method is used to get the rotation angle and axis of an
+// orientation quaternion.
+// TODO : Test this method
+void Quaternion::getRotationAngleAxis(double& angle, Vector3D& axis) const {
+    Quaternion quaternion;
+
+    // If the quaternion is unit
+    if (length() == 1.0) {
+        quaternion = *this;
+    }
+    else {
+        // We compute the unit quaternion
+        quaternion = getUnit();
+    }
+
+    // Compute the roation angle
+    angle = acos(quaternion.w) * 2.0;
+
+    // Compute the 3D rotation axis
+    Vector3D rotationAxis(quaternion.x, quaternion.y, quaternion.z);
+
+    // Normalize the rotation axis
+    rotationAxis = rotationAxis.getUnit();
+
+    // Set the rotation axis values
+    axis.setAllValues(rotationAxis.getX(), rotationAxis.getY(), rotationAxis.getZ());
+}
+
 // Compute the spherical linear interpolation between two quaternions.
 // The t argument has to be such that 0 <= t <= 1.
 // TODO : Test this method

sources/reactphysics3d/mathematics/Quaternion.h

@@ -62,7 +62,7 @@ class Quaternion
         Quaternion getConjugate() const;                                      // Return the conjugate quaternion
         Quaternion getInverse() const throw (MathematicsException);           // Return the inverse of the quaternion
         double scalarProduct(const Quaternion& quaternion) const;             // Scalar product between two quaternions
-
+        void getRotationAngleAxis(double& angle, Vector3D& axis) const;       // Compute the rotation angle (in radians) and the axis
         static Quaternion slerp(const Quaternion& quaternion1,
                                 const Quaternion& quaternion2, double t);     // Compute the spherical linear interpolation between two quaternions