1 files changed, 64 insertions, 0 deletions
diff --git a/platform/darwin/src/MGLGeometry_Private.h b/platform/darwin/src/MGLGeometry_Private.h
index 3e029e8ee0..7ad8314a79 100644
--- a/platform/darwin/src/MGLGeometry_Private.h
+++ b/platform/darwin/src/MGLGeometry_Private.h
@@ -8,6 +8,26 @@
 #import <mbgl/util/geo.hpp>
 #import <mbgl/util/geometry.hpp>
 
+typedef double MGLLocationRadians;
+typedef double MGLRadianDistance;
+typedef double MGLRadianDirection;
+
+/** Defines the coordinate by a `MGLRadianCoordinate2D`. */
+typedef struct MGLRadianCoordinate2D {
+    MGLLocationRadians latitude;
+    MGLLocationRadians longitude;
+} MGLRadianCoordinate2D;
+
+/**
+ Creates a new `MGLRadianCoordinate2D` from the given latitudinal and longitudinal.
+ */
+NS_INLINE MGLRadianCoordinate2D MGLRadianCoordinate2DMake(MGLLocationRadians latitude, MGLLocationRadians longitude) {
+    MGLRadianCoordinate2D radianCoordinate;
+    radianCoordinate.latitude = latitude;
+    radianCoordinate.longitude = longitude;
+    return radianCoordinate;
+}
+
 /// Returns the smallest rectangle that contains both the given rectangle and
 /// the given point.
 CGRect MGLExtendRect(CGRect rect, CGPoint point);
@@ -18,6 +38,10 @@ NS_INLINE mbgl::Point<double> MGLPointFromLocationCoordinate2D(CLLocationCoordin
     return mbgl::Point<double>(coordinate.longitude, coordinate.latitude);
 }
 
+NS_INLINE CLLocationCoordinate2D MGLLocationCoordinate2DFromPoint(mbgl::Point<double> point) {
+    return CLLocationCoordinate2DMake(point.y, point.x);
+}
+
 NS_INLINE CLLocationCoordinate2D MGLLocationCoordinate2DFromLatLng(mbgl::LatLng latLng) {
     return CLLocationCoordinate2DMake(latLng.latitude(), latLng.longitude());
 }
@@ -59,3 +83,43 @@ CLLocationDistance MGLAltitudeForZoomLevel(double zoomLevel, CGFloat pitch, CLLo
     @param size The size of the viewport.
     @return A zero-based zoom level. */
 double MGLZoomLevelForAltitude(CLLocationDistance altitude, CGFloat pitch, CLLocationDegrees latitude, CGSize size);
+
+/** Returns MGLRadianCoordinate2D, converted from CLLocationCoordinate2D. */
+NS_INLINE MGLRadianCoordinate2D MGLRadianCoordinateFromLocationCoordinate(CLLocationCoordinate2D locationCoordinate) {
+    return MGLRadianCoordinate2DMake(MGLRadiansFromDegrees(locationCoordinate.latitude),
+                                     MGLRadiansFromDegrees(locationCoordinate.longitude));
+}
+
+/*
+ Returns the distance in radians given two coordinates.
+ */
+NS_INLINE MGLRadianDistance MGLDistanceBetweenRadianCoordinates(MGLRadianCoordinate2D from, MGLRadianCoordinate2D to)
+{
+    double a = pow(sin((to.latitude - from.latitude) / 2), 2)
+                + pow(sin((to.longitude - from.longitude) / 2), 2) * cos(from.latitude) * cos(to.latitude);
+    
+    return 2 * atan2(sqrt(a), sqrt(1 - a));
+}
+
+/*
+ Returns direction in radians given two coordinates.
+ */
+NS_INLINE MGLRadianDirection MGLRadianCoordinatesDirection(MGLRadianCoordinate2D from, MGLRadianCoordinate2D to) {
+    double a = sin(to.longitude - from.longitude) * cos(to.latitude);
+    double b = cos(from.latitude) * sin(to.latitude)
+                - sin(from.latitude) * cos(to.latitude) * cos(to.longitude - from.longitude);
+    return atan2(a, b);
+}
+
+/*
+ Returns coordinate at a given distance and direction away from coordinate.
+ */
+NS_INLINE MGLRadianCoordinate2D MGLRadianCoordinateAtDistanceFacingDirection(MGLRadianCoordinate2D coordinate,
+                                                                             MGLRadianDistance distance,
+                                                                             MGLRadianDirection direction) {
+    double otherLatitude = asin(sin(coordinate.latitude) * cos(distance)
+                                + cos(coordinate.latitude) * sin(distance) * cos(direction));
+    double otherLongitude = coordinate.longitude + atan2(sin(direction) * sin(distance) * cos(coordinate.latitude),
+                                                         cos(distance) - sin(coordinate.latitude) * sin(otherLatitude));
+    return MGLRadianCoordinate2DMake(otherLatitude, otherLongitude);
+}