Ref T717, calculate a new position in distance from given position

src/blackmisc/geo/coordinategeodetic.cpp

@@ -50,7 +50,7 @@ namespace BlackMisc
         {
             if (coordinate1.isNull() || coordinate2.isNull()) { return CLength::null(); }
             // if (coordinate1.equalNormalVectorDouble(coordinate2)) { return CLength(0, CLengthUnit::defaultUnit()); }
-            static const float earthRadiusMeters = 6371000.8f;
+            constexpr float earthRadiusMeters = 6371000.8f;
 
             const QVector3D v1 = coordinate1.normalVector();
             const QVector3D v2 = coordinate2.normalVector();
@@ -299,6 +299,41 @@ namespace BlackMisc
             this->setNormalVector(coordinate.normalVectorDouble());
         }
 
+        CCoordinateGeodetic CCoordinateGeodetic::calculatePosition(const CLength &distance, const CAngle &relBearing) const
+        {
+            if (this->isNull()) { return CCoordinateGeodetic::null(); }
+            if (distance.isNull() || distance.isNegativeWithEpsilonConsidered() || relBearing.isNull()) { return CCoordinateGeodetic::null(); }
+            if (distance.isZeroEpsilonConsidered()) { return *this; }
+
+            // http://www.movable-type.co.uk/scripts/latlong.html#destPoint
+            // https://stackoverflow.com/a/879531/356726
+            // https://www.cosmocode.de/en/blog/gohr/2010-06/29-calculate-a-destination-coordinate-based-on-distance-and-bearing-in-php
+            constexpr double earthRadiusMeters = 6371000.8;
+            const double startLatRad = this->latitude().value(CAngleUnit::rad());
+            const double startLngRad = this->longitude().value(CAngleUnit::rad());
+            const double bearingRad  = relBearing.value(CAngleUnit::rad());
+            const double distRatio   = distance.value(CLengthUnit::m()) / earthRadiusMeters;
+
+            const double newLatRad = asin(sin(startLatRad) * cos(distRatio) + cos(startLatRad) * sin(distRatio) * cos(bearingRad));
+            double newLngRad = 0;
+
+            constexpr double epsilon = 1E-06;
+            if (cos(newLatRad) == 0 || qAbs(cos(newLatRad)) < epsilon)
+                newLngRad = startLngRad;
+            else
+            {
+                // λ1 + Math.atan2(Math.sin(brng)*Math.sin(d/R)*Math.cos(φ1), Math.cos(d/R)-Math.sin(φ1)*Math.sin(φ2));
+                newLngRad = startLngRad + atan2(sin(bearingRad) * sin(distRatio) * cos(startLatRad), cos(distRatio) - sin(startLatRad) * sin(newLatRad));
+                newLngRad = fmod(newLngRad + 3 * M_PI, 2 * M_PI) - M_PI; // normalize +-180deg
+            }
+
+            CCoordinateGeodetic copy = *this;
+            const CLatitude  lat(newLatRad, CAngleUnit::rad());
+            const CLongitude lng(newLngRad, CAngleUnit::rad());
+            copy.setLatLong(lat, lng);
+            return copy;
+        }
+
         CLatitude CCoordinateGeodetic::latitude() const
         {
             return { std::atan2(m_z, std::hypot(m_x, m_y)), CAngleUnit::rad() };

src/blackmisc/geo/coordinategeodetic.h

@@ -247,6 +247,9 @@ namespace BlackMisc
             //! Constructor by interface
             CCoordinateGeodetic(const ICoordinateGeodetic &coordinate);
 
+            //! Calculate a position in distance/bearing
+            CCoordinateGeodetic calculatePosition(const PhysicalQuantities::CLength &distance, const PhysicalQuantities::CAngle &relBearing) const;
+
             //! \copydoc ICoordinateGeodetic::latitude
             virtual CLatitude latitude() const override;