Bugfix: _cameraForBoxAndBearing not fitting bounds properly when usin…

…g asymettrical camera viewport and bearing (#3591)

* failing test

* tests fixes which were incorrect and code update

* code improvements

* small cleanup

* fix linting findings

* update changelog

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 ### 🐞 Bug fixes
 - Fix wheel zoom to be into the same direction above or under the horizon ([#3398](https://github.com/maplibre/maplibre-gl-js/issues/3398))
+- Fix _cameraForBoxAndBearing not fitting bounds properly when using asymettrical camera viewport and bearing.
 - _...Add new stuff here..._
 
 ## 4.0.0-pre.4

src/ui/camera.test.ts

@@ -8,6 +8,7 @@ import {mercatorZfromAltitude} from '../geo/mercator_coordinate';
 import {Terrain} from '../render/terrain';
 import {LngLat, LngLatLike} from '../geo/lng_lat';
 import {Event} from '../util/evented';
+import {LngLatBounds} from '../geo/lng_lat_bounds';
 
 beforeEach(() => {
     setMatchMedia();
@@ -1930,7 +1931,7 @@ describe('#cameraForBounds', () => {
         const transform = camera.cameraForBounds(bb, {bearing: 175});
 
         expect(fixedLngLat(transform.center, 4)).toEqual({lng: -100.5, lat: 34.7171});
-        expect(fixedNum(transform.zoom, 3)).toBe(2.558);
+        expect(fixedNum(transform.zoom, 3)).toBe(2.396);
         expect(transform.bearing).toBe(175);
     });
 
@@ -1940,7 +1941,7 @@ describe('#cameraForBounds', () => {
         const transform = camera.cameraForBounds(bb, {bearing: -30});
 
         expect(fixedLngLat(transform.center, 4)).toEqual({lng: -100.5, lat: 34.7171});
-        expect(fixedNum(transform.zoom, 3)).toBe(2.392);
+        expect(fixedNum(transform.zoom, 3)).toBe(2.222);
         expect(transform.bearing).toBe(-30);
     });
 
@@ -2000,6 +2001,24 @@ describe('#cameraForBounds', () => {
 
         expect(fixedLngLat(transform.center, 4)).toEqual({lng: -103.3761, lat: 43.0929});
     });
+
+    test('asymmetrical transform using LngLatBounds instance', () => {
+        const transform = new Transform(2, 10, 0, 60, false);
+        transform.resize(2048, 512);
+
+        const camera = attachSimulateFrame(new CameraMock(transform, {} as any));
+        camera._update = () => {};
+
+        const bb = new LngLatBounds();
+        bb.extend([-66.9326, 49.5904]);
+        bb.extend([-125.0011, 24.9493]);
+
+        const rotatedTransform = camera.cameraForBounds(bb, {bearing: 45});
+
+        expect(fixedLngLat(rotatedTransform.center, 4)).toEqual({lng: -95.9669, lat: 38.3048});
+        expect(fixedNum(rotatedTransform.zoom, 3)).toBe(2.507);
+        expect(rotatedTransform.bearing).toBe(45);
+    });
 });
 
 describe('#fitBounds', () => {

src/ui/camera.ts

@@ -1,4 +1,4 @@
-import {extend, warnOnce, clamp, wrap, defaultEasing, pick} from '../util/util';
+import {extend, warnOnce, clamp, wrap, defaultEasing, pick, degreesToRadians} from '../util/util';
 import {interpolates} from '@maplibre/maplibre-gl-style-spec';
 import {browser} from '../util/browser';
 import {LngLat} from '../geo/lng_lat';
@@ -692,15 +692,30 @@ export abstract class Camera extends Evented {
         const tr = this.transform;
         const edgePadding = tr.padding;
 
-        // We want to calculate the upper right and lower left of the box defined by p0 and p1
-        // in a coordinate system rotate to match the destination bearing.
-        const p0world = tr.project(LngLat.convert(p0));
-        const p1world = tr.project(LngLat.convert(p1));
-        const p0rotated = p0world.rotate(-bearing * Math.PI / 180);
-        const p1rotated = p1world.rotate(-bearing * Math.PI / 180);
+        // Consider all corners of the rotated bounding box derived from the given points
+        // when find the camera position that fits the given points.
+        const bounds = new LngLatBounds(p0, p1);
+        const nwWorld = tr.project(bounds.getNorthWest());
+        const neWorld = tr.project(bounds.getNorthEast());
+        const seWorld = tr.project(bounds.getSouthEast());
+        const swWorld = tr.project(bounds.getSouthWest());
 
-        const upperRight = new Point(Math.max(p0rotated.x, p1rotated.x), Math.max(p0rotated.y, p1rotated.y));
-        const lowerLeft = new Point(Math.min(p0rotated.x, p1rotated.x), Math.min(p0rotated.y, p1rotated.y));
+        const bearingRadians = degreesToRadians(-bearing);
+
+        const nwRotatedWorld = nwWorld.rotate(bearingRadians);
+        const neRotatedWorld = neWorld.rotate(bearingRadians);
+        const seRotatedWorld = seWorld.rotate(bearingRadians);
+        const swRotatedWorld = swWorld.rotate(bearingRadians);
+
+        const upperRight = new Point(
+            Math.max(nwRotatedWorld.x, neRotatedWorld.x, swRotatedWorld.x, seRotatedWorld.x),
+            Math.max(nwRotatedWorld.y, neRotatedWorld.y, swRotatedWorld.y, seRotatedWorld.y)
+        );
+
+        const lowerLeft = new Point(
+            Math.min(nwRotatedWorld.x, neRotatedWorld.x, swRotatedWorld.x, seRotatedWorld.x),
+            Math.min(nwRotatedWorld.y, neRotatedWorld.y, swRotatedWorld.y, seRotatedWorld.y)
+        );
 
         // Calculate zoom: consider the original bbox and padding.
         const size = upperRight.sub(lowerLeft);
@@ -721,11 +736,14 @@ export abstract class Camera extends Evented {
         const paddingOffsetX = (options.padding.left - options.padding.right) / 2;
         const paddingOffsetY = (options.padding.top - options.padding.bottom) / 2;
         const paddingOffset = new Point(paddingOffsetX, paddingOffsetY);
-        const rotatedPaddingOffset = paddingOffset.rotate(bearing * Math.PI / 180);
+        const rotatedPaddingOffset = paddingOffset.rotate(degreesToRadians(bearing));
         const offsetAtInitialZoom = offset.add(rotatedPaddingOffset);
         const offsetAtFinalZoom = offsetAtInitialZoom.mult(tr.scale / tr.zoomScale(zoom));
 
-        const center =  tr.unproject(p0world.add(p1world).div(2).sub(offsetAtFinalZoom));
+        const center = tr.unproject(
+            // either world diagonal can be used (NW-SE or NE-SW)
+            nwWorld.add(seWorld).div(2).sub(offsetAtFinalZoom)
+        );
 
         return {
             center,

src/util/util.ts

@@ -679,3 +679,13 @@ export function subscribe(target: Subscriber, message: keyof WindowEventMap, lis
         }
     };
 }
+
+/**
+ * This method converts degrees to radians.
+ * The return value is the radian value.
+ * @param degrees - The number of degrees
+ * @returns radians
+ */
+export function degreesToRadians(degrees: number): number {
+    return degrees * Math.PI / 180;
+}