Base: [skip ci] add method to check for null vector

src/Base/Vector3D.cpp

@@ -416,6 +416,13 @@ Vector3<_Precision> & Vector3<_Precision>::Normalize (void)
     return *this;
 }
 
+template <class _Precision>
+bool Vector3<_Precision>::IsNull() const
+{
+    _Precision n{0.0};
+    return (x == n) && (y == n) && (z == n);
+}
+
 template <class _Precision>
 _Precision Vector3<_Precision>::GetAngle (const Vector3 &rcVect) const
 {

src/Base/Vector3D.h

@@ -161,6 +161,8 @@ public:
     _Precision Sqr (void) const;
     /// Set length to 1.
     Vector3 & Normalize (void);
+    /// Checks whether this is the null vector
+    bool IsNull() const;
     /// Get angle between both vectors. The returned value lies in the interval [0,pi].
     _Precision GetAngle (const Vector3 &rcVect) const;
     /** Transforms this point to the coordinate system defined by origin \a rclBase,