.. _cb_tonmasteringneedcb:

TOnMasteringNeedCB
------------------------------------------
This callback function is used to check whether the **robot’s axes have been twisted or misaligned** by an external force. When this event occurs, the robot requires **re-mastering (axis alignment)** through homing. The alignment completion can then be verified using the :ref:`TOnHommingCompletedCB <cb_tonhommingcompletedcb>` callback.

See :ref:`Rules for callback functions <callback_rules>`.

**Defined in:** ``DRFLEx.h``

.. code-block:: cpp

   // typedef (DRFL.h)
   typedef void (*TOnMasteringNeedCB)();

   // registration API (internal + wrapper)
   DRFL_API void _set_on_mastering_need(LPROBOTCONTROL pCtrl, TOnMasteringNeedCB pCallbackFunc);
   void set_on_mastering_need(TOnMasteringNeedCB pCallbackFunc)
   {
       _set_on_mastering_need(_rbtCtrl, pCallbackFunc);
   };

**Parameter** |br|
None

**Return** |br|
None

**Example**

.. code-block:: cpp

   #include "DRFLEx.h"
   #include <iostream>
   #include <atomic>
   #include <thread>
   #include <chrono>
   using namespace DRAFramework;
   using namespace std;

   std::atomic<bool> g_bNeedHoming(false);

   // Callback triggered when robot mastering (axis alignment) is required
   void OnMasteringNeedCB()
   {
       cout << "[MASTERING] Axis misalignment detected. Requesting homing sequence..." << endl;

       // Request homing from the main loop; do not call move_home here
       g_bNeedHoming = true;
   }

   int main()
   {
       CDRFLEx drfl;

       // Connect to the robot controller
       if (!drfl.open_connection("192.168.137.100")) {
           cout << "Failed to connect to controller." << endl;
           return -1;
       }

       // Register mastering-needed callback
       drfl.set_on_mastering_need(OnMasteringNeedCB);

       // Main loop: start homing outside the callback
       while (true)
       {
           if (g_bNeedHoming) {
               g_bNeedHoming = false;
               // Initiate homing mode for re-alignment of robot axes
               drfl.move_home(MOVE_HOME_MECHANIC, 1);
           }
           std::this_thread::sleep_for(std::chrono::milliseconds(100));
       }

       drfl.close_connection();
       return 0;
   }

**Notes**

- This callback is invoked when the controller detects **axis offset** that requires re-mastering.  
- Use this event to trigger an **automatic homing or alignment process**.  
- Use :ref:`TOnHommingCompletedCB <cb_tonhommingcompletedcb>` to confirm when re-alignment finishes.