[core] Fix screen coordinates when crossing the antimeridian

If the center and point coordinates are not in the same side of the
antimeridian, we need to unwrap the point longitude to make sure
it can still be seen from the visible side of the antimeridian that is
opposite to the center side.

Fixes #4155.

1 files changed, 15 insertions, 1 deletions

diff --git a/src/mbgl/map/transform.cpp b/src/mbgl/map/transform.cpp
index 45386b9dc8..d3cd30a627 100644
--- a/src/mbgl/map/transform.cpp
+++ b/src/mbgl/map/transform.cpp
@@ -660,7 +660,21 @@ void Transform::setGestureInProgress(bool inProgress) {
 
 ScreenCoordinate Transform::latLngToScreenCoordinate(const LatLng& latLng) const {
     if (!latLng) return {};
-    ScreenCoordinate point = state.latLngToScreenCoordinate(latLng);
+
+    // If the center and point coordinates are not in the same side of the
+    // antimeridian, we need to unwrap the point longitude to make sure it can
+    // still be seen from the visible side of the antimeridian that is opposite
+    // to the center side.
+    double longitude = latLng.longitude;
+    const double centerLng = getLatLng().longitude;
+    if (centerLng - latLng.longitude > util::LONGITUDE_MAX) {
+        if (centerLng > 0 && latLng.longitude < 0) {
+            longitude += util::DEGREES_MAX;
+        } else if (centerLng < 0 && latLng.longitude > 0) {
+            longitude -= util::DEGREES_MAX;
+        }
+    }
+    ScreenCoordinate point = state.latLngToScreenCoordinate({ latLng.latitude, longitude });
     point.y = state.height - point.y;
     return point;
 }