refs #865, set on ground flag in interpolator

src/blackmisc/simulation/interpolator.cpp

@@ -115,6 +115,48 @@ namespace BlackMisc
             situation.setGroundElevation(elevation);
         }
 
+        void IInterpolator::setGroundFlagFromInterpolator(const CInterpolationHints &hints, double groundFactor, CAircraftSituation &situation)
+        {
+            // by interpolation
+            if (groundFactor >= 1.0)
+            {
+                situation.setOnGround(CAircraftSituation::OnGround, CAircraftSituation::OnGroundByInterpolation);
+                return;
+            }
+            if (groundFactor < 1.0 && groundFactor >= 0.0)
+            {
+                situation.setOnGround(CAircraftSituation::NotOnGround, CAircraftSituation::OnGroundByInterpolation);
+                return;
+            }
+
+            // no value by factor, guess on elevation
+            const CLength heightAboveGround(situation.getHeightAboveGround());
+            const CLength cgAboveGround(hints.getCGAboveGround());
+            if (!heightAboveGround.isNull())
+            {
+                const bool og = cgAboveGround.isNull() ?
+                                heightAboveGround.value(CLengthUnit::m()) < 1.0 :
+                                heightAboveGround <= cgAboveGround;
+                situation.setOnGround(og ? CAircraftSituation::OnGround : CAircraftSituation::NotOnGround, CAircraftSituation::OnGroundByElevation);
+            }
+
+            // for VTOL aircraft we give up
+            if (hints.isVtolAircraft())
+            {
+                situation.setOnGround(CAircraftSituation::OnGroundSituationUnknown, CAircraftSituation::OnGroundReliabilityNoSet);
+                return;
+            }
+
+            // we guess on speed, pitch and bank by excluding situations
+            situation.setOnGround(CAircraftSituation::NotOnGround, CAircraftSituation::OnGroundByGuessing);
+            if (qAbs(situation.getPitch().value(CAngleUnit::deg())) > 10) { return; }
+            if (qAbs(situation.getBank().value(CAngleUnit::deg())) > 10)  { return; }
+            if (situation.getGroundSpeed().value(CSpeedUnit::km_h()) > 50) { return; }
+
+            // not sure, but this is a guess
+            situation.setOnGround(CAircraftSituation::OnGround, CAircraftSituation::OnGroundByGuessing);
+        }
+
         bool IInterpolator::InterpolationStatus::allTrue() const
         {
             return m_interpolationSucceeded && m_changedPosition;

src/blackmisc/simulation/interpolator.h

@@ -142,6 +142,9 @@ namespace BlackMisc
             //! Set the ground elevation from hints, if possible and not already set
             static void setGroundElevationFromHint(const CInterpolationHints &hints, BlackMisc::Aviation::CAircraftSituation &situation);
 
+            //! Set on ground flag
+            static void setGroundFlagFromInterpolator(const CInterpolationHints &hints, double groundFactor, BlackMisc::Aviation::CAircraftSituation &situation);
+
             CInterpolationAndRenderingSetup m_setup; //!< allows to disable debug messages
             mutable QReadWriteLock m_lock; //!< lock interpolator
         };

src/blackmisc/simulation/interpolatorlinear.cpp

@@ -158,6 +158,13 @@ namespace BlackMisc
                                                                oldAlt.getReferenceDatum()));
                     }
                 }
+                IInterpolator::setGroundFlagFromInterpolator(hints, groundFactor, currentSituation);
+            }
+            else
+            {
+                // guess ground flag
+                constexpr double NoGroundFactor = -1;
+                IInterpolator::setGroundFlagFromInterpolator(hints, NoGroundFactor, currentSituation);
             }
 
             if (!setup.isForcingFullInterpolation() && !hints.isVtolAircraft() && newVec == oldVec && oldAlt == newAlt)