Don't allow carrier's path over land in UI

game/server/controlpoints/routes.py

@@ -89,6 +89,15 @@ def set_destination(
             detail=f"Cannot move {cp} more than "
             f"{cp.max_move_distance.nautical_miles}nm.",
         )
+    if (
+        cp.is_fleet
+        and game.theater.landmap
+        and game.theater.landmap.land_inbetween(cp.position, point)
+    ):
+        raise HTTPException(
+            status.HTTP_400_BAD_REQUEST,
+            detail=f"Cannot move {cp} over land.",
+        )
     cp.target_position = point
     from .. import EventStream
 

game/theater/landmap.py

@@ -10,7 +10,7 @@ from dcs.drawing.polygon import FreeFormPolygon
 from dcs.mapping import Point
 from dcs.mission import Mission
 from dcs.terrain.terrain import Terrain
-from shapely import geometry
+from shapely import geometry, LineString
 from shapely.geometry import MultiPolygon, Polygon
 
 
@@ -32,6 +32,10 @@ class Landmap:
     def inclusion_zone_only(self) -> MultiPolygon:
         return self.inclusion_zones - self.exclusion_zones - self.sea_zones
 
+    def land_inbetween(self, a: Point, b: Point) -> bool:
+        line = LineString([[a.x, a.y], [b.x, b.y]])
+        return self.inclusion_zones.intersects(line)
+
 
 def load_landmap(filename: Path) -> Optional[Landmap]:
     try: