Euler angle access

src/ODE/sixDOF/finiteRotation/finiteRotation.C

@@ -70,6 +70,33 @@ Foam::scalar Foam::finiteRotation::rotAngle(const tensor& rotT)
 }
 
 
+Foam::vector Foam::finiteRotation::eulerAngles(const tensor& rotT)
+{
+    // Define a vector containing euler angles (x = roll, y = pitch, z = yaw)
+    vector eulerAngles;
+
+    scalar& rollAngle = eulerAngles.x();
+    scalar& pitchAngle = eulerAngles.y();
+    scalar& yawAngle = eulerAngles.z();
+
+    // Calculate roll angle
+    rollAngle = atan2(rotT.yz(), rotT.zz());
+
+    const scalar c2 = sqrt(rotT.xx() + rotT.xy());
+
+    // Calculate pitch angle
+    pitchAngle = atan2(-rotT.xz(), c2);
+
+    const scalar s1 = sin(rollAngle);
+    const scalar c1 = cos(rollAngle);
+
+    // Calculate yaw angle
+    yawAngle = atan2(s1*rotT.zx() - c1*rotT.yx(), c1*rotT.yy() - s1*rotT.zy());
+
+    return eulerAngles;
+}
+
+
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 Foam::finiteRotation::finiteRotation(const HamiltonRodriguezRot& rot)
@@ -139,6 +166,12 @@ Foam::scalar Foam::finiteRotation::rotAngle() const
 }
 
 
+Foam::vector Foam::finiteRotation::eulerAngles() const
+{
+    return eulerAngles(rotTensor_);
+}
+
+
 const Foam::tensor& Foam::finiteRotation::rotIncrementTensor() const
 {
     return rotIncrementTensor_;

src/ODE/sixDOF/finiteRotation/finiteRotation.H

@@ -69,6 +69,11 @@ class finiteRotation
         //- Calculate rotation angle from given rotation tensor
         static scalar rotAngle(const tensor& rotT);
 
+        //- Calculate Euler angles (x-y-z (roll-pitch-yaw) convenction) from
+        //  given rotation tensor. Reference: Mike Day, Insomniac Games,
+        //  Extracting Euler Angles from a Rotation Matrix.
+        static vector eulerAngles(const tensor& rotT);
+
 
 public:
 
@@ -110,6 +115,9 @@ public:
         //- Return rotation angle
         scalar rotAngle() const;
 
+        //- Return Euler angles (see static function eulerAngles for convention)
+        vector eulerAngles() const;
+
         // Transformations between new and previous rotation
         const tensor& rotIncrementTensor() const;
 

src/ODE/sixDOF/sixDOFqODE/sixDOFqODE.H

@@ -236,6 +236,9 @@ public:
             //- Return average velocity of origin for the previous time-step
             inline const dimensionedVector& Uaverage() const;
 
+            //- Return finite rotation
+            inline const finiteRotation& rotation() const;
+
             //- Return acceleration of origin
             inline dimensionedVector A() const;
 
@@ -246,7 +249,7 @@ public:
             inline dimensionedScalar rotAngle() const;
 
 
-        // Non-constant access to
+        // Non-constant access
 
             //- Set position of origin
             inline void setXrel(const vector& x);

src/ODE/sixDOF/sixDOFqODE/sixDOFqODEI.H

@@ -172,6 +172,12 @@ const Foam::dimensionedVector& Foam::sixDOFqODE::Uaverage() const
 }
 
 
+const Foam::finiteRotation& Foam::sixDOFqODE::rotation() const
+{
+    return rotation_;
+}
+
+
 Foam::vector Foam::sixDOFqODE::rotVectorAverage() const
 {
     return rotation_.rotVectorAverage();