AP_NavEKF3: add configuredToUseGPSForPosXY

libraries/AP_NavEKF3/AP_NavEKF3.cpp

@@ -1418,6 +1418,13 @@ bool NavEKF3::using_external_yaw(void) const
     return core[primary].using_external_yaw();
 }
 
+// check if configured to use GPS for horizontal position estimation
+bool NavEKF3::configuredToUseGPSForPosXY(void) const
+{
+    // 0 = use 3D velocity, 1 = use 2D velocity, 2 = use no velocity, 3 = do not use GPS
+    return  (sources.getPosXYSource() == AP_NavEKF_Source::SourceXY::GPS);
+}
+
 // write the raw optical flow measurements
 // rawFlowQuality is a measured of quality between 0 and 255, with 255 being the best quality
 // rawFlowRates are the optical flow rates in rad/sec about the X and Y sensor axes.

libraries/AP_NavEKF3/AP_NavEKF3.h

@@ -387,7 +387,10 @@ public:
 
     // are we using an external yaw source? This is needed by AHRS attitudes_consistent check
     bool using_external_yaw(void) const;
-    
+
+    // check if configured to use GPS for horizontal position estimation
+    bool configuredToUseGPSForPosXY(void) const;
+
     // Writes the default equivalent airspeed in m/s to be used in forward flight if a measured airspeed is required and not available.
     void writeDefaultAirSpeed(float airspeed);