mobility: Expose child mobility model to parent position

src/mobility/model/hierarchical-mobility-model.cc

@@ -117,7 +117,7 @@ HierarchicalMobilityModel::DoGetPosition (void) const
       return m_child->GetPosition ();
     }
   Vector parentPosition = m_parent->GetPosition ();
-  Vector childPosition = m_child->GetPosition ();
+  Vector childPosition = m_child->GetPositionWithReference (parentPosition);
   return Vector (parentPosition.x + childPosition.x,
                  parentPosition.y + childPosition.y,
                  parentPosition.z + childPosition.z);

src/mobility/model/mobility-model.cc

@@ -65,6 +65,19 @@ MobilityModel::GetPosition (void) const
 {
   return DoGetPosition ();
 }
+Vector
+MobilityModel::GetPositionWithReference (const Vector& referencePosition) const
+{
+  return DoGetPositionWithReference (referencePosition);
+}
+
+// Default implementation ignores referencePosition
+Vector
+MobilityModel::DoGetPositionWithReference (const Vector& referencePosition) const
+{
+  return DoGetPosition ();
+}
+
 Vector
 MobilityModel::GetVelocity (void) const
 {

src/mobility/model/mobility-model.h

@@ -51,6 +51,18 @@ public:
    * \return the current position
    */
   Vector GetPosition (void) const;
+  /**
+   * This method may be used if the position returned may depend on some
+   * reference position provided.  For example, in a hierarchical mobility
+   * model that is buildings-aware, the child mobility model may not be able
+   * to determine if it is inside or outside of a building unless it knows
+   * the parent position.
+   *
+   * \param referencePosition reference position to consider
+   * \return the current position based on the provided referencePosition
+   * \sa ns3::MobilityModel::DoGetPositionWithReference
+   */
+  Vector GetPositionWithReference (const Vector &referencePosition) const;
   /**
    * \param position the position to set.
    */
@@ -100,6 +112,14 @@ private:
    * implement this method.
    */
   virtual Vector DoGetPosition (void) const = 0;
+  /**
+   * \param referencePosition the reference position to consider
+   * \return the current position.
+   *
+   * Unless subclasses override, this method will disregard the reference
+   * position and return "DoGetPosition (void)".
+   */
+  virtual Vector DoGetPositionWithReference (const Vector& referencePosition) const;
   /**
    * \param position the position to set.
    *