bbox calculation with bearings

Author: louisgreiner

src/curves.rs

@@ -364,15 +364,23 @@ impl Curve for SphericalLineStringCurve {
     }
 
     fn bbox(&self) -> Rect {
-        let bounding_rect = self.geom.bounding_rect().unwrap();
+        let min_point = geo::Point(self.geom.bounding_rect().unwrap().min());
+        let max_point = geo::Point(self.geom.bounding_rect().unwrap().max());
+        
+        // add max_extend distance in South and then West direction
+        let min_point_extended = min_point.haversine_destination(180., self.max_extent).haversine_destination(270., self.max_extent);
+       
+        // add max_extend distance in North and then East direction
+        let max_point_extended = max_point.haversine_destination(0., self.max_extent).haversine_destination(90., self.max_extent);
+
         Rect::new(
             coord! {
-                x: bounding_rect.min().x - self.max_extent,
-                y: bounding_rect.min().y - self.max_extent,
+                x: min_point_extended.x(),
+                y: min_point_extended.y(),
             },
             coord! {
-                x: bounding_rect.max().x + self.max_extent,
-                y: bounding_rect.max().y + self.max_extent,
+                x: max_point_extended.x(),
+                y: max_point_extended.y(),
             },
         )
     }
@@ -730,11 +738,20 @@ mod tests {
 
     #[test]
     fn spherical_bbox() {
-        let paris_to_new_york = SphericalLineStringCurve::new(line_string![PARIS, NEW_YORK], 1.);
+        let paris_to_new_york = SphericalLineStringCurve::new(line_string!
+            [
+                coord! {x: -7.65, y: 51.79},
+                coord! {x: -7.31, y: 51.94},
+                coord! {x: -7.31, y: 51.54},
+                coord! {x: -6.84, y: 51.69},
+                coord! {x: -6.39, y: 51.55},
+                ],
+             100.,
+        );
         let bbox = paris_to_new_york.bbox();
 
-        assert_eq!(bbox.min(), coord! {x: -75.01, y: 39.71});
-        assert_eq!(bbox.max(), coord! {x: 3.35, y: 49.86});
+        assert_eq!(bbox.min(), coord! {x: -7.651445898208635, y: 51.53910067075082});
+        assert_eq!(bbox.max(), coord! {x: -6.388541186830253, y: 51.9408993113492});
     }
 
     #[test]