Get the right zoom when querying elevation

CHANGELOG.md

@@ -4,6 +4,7 @@
 - _...Add new stuff here..._
 
 ### 🐞 Bug fixes
+- Fix getting the right zoom for getElevationForLngLat ([#6825](https://github.com/maplibre/maplibre-gl-js/pull/6825)) (by [@HarelM](https://github.com/HarelM))
 - _...Add new stuff here..._
 
 ## 5.14.0

src/data/dem_data.ts

@@ -120,7 +120,7 @@ export class DEMData {
     }
 
     _idx(x: number, y: number) {
-        if (x < -1 || x >= this.dim + 1 ||  y < -1 || y >= this.dim + 1) throw new RangeError('out of range source coordinates for DEM data');
+        if (x < -1 || x >= this.dim + 1 ||  y < -1 || y >= this.dim + 1) throw new RangeError(`Out of range source coordinates for DEM data. x: ${x}, y: ${y}, dim: ${this.dim}`);
         return (y + 1) * this.stride + (x + 1);
     }
 

src/geo/projection/mercator_transform.ts

@@ -323,7 +323,7 @@ export class MercatorTransform implements ITransform {
 
     locationToScreenPoint(lnglat: LngLat, terrain?: Terrain): Point {
         return terrain ?
-            this.coordinatePoint(MercatorCoordinate.fromLngLat(lnglat), terrain.getElevationForLngLat(lnglat), this._pixelMatrix3D) :
+            this.coordinatePoint(MercatorCoordinate.fromLngLat(lnglat), terrain.getElevationForLngLat(lnglat, this), this._pixelMatrix3D) :
             this.coordinatePoint(MercatorCoordinate.fromLngLat(lnglat));
     }
 

src/render/terrain.test.ts

@@ -8,6 +8,7 @@ import {OverscaledTileID} from '../tile/tile_id';
 import {Tile} from '../tile/tile';
 import {LngLat} from '../geo/lng_lat';
 import {MAX_TILE_ZOOM, MIN_TILE_ZOOM} from '../util/util';
+import {MercatorTransform} from '../geo/projection/mercator_transform';
 import type {TileManager} from '../tile/tile_manager';
 import type {TerrainSpecification} from '@maplibre/maplibre-gl-style-spec';
 import type {DEMData} from '../data/dem_data';
@@ -291,15 +292,36 @@ describe('Terrain', () => {
         expect(mockTerrain.getDEMElevation(null, 0.4, 0.2)).toBeCloseTo(42);
     });
 
-    test('getElevationForLngLat uses source max zoom', () => {
-        const terrain = new Terrain(null, {_source: {tileSize: 512}} as any, {} as any);
+    test('getElevationForLngLat uses covering tiles to get the right zoom', () => {
+        const zoom = 10;
+        const painter = {
+            context: new Context(gl),
+            width: 1,
+            height: 1,
+            getTileTexture: () => null
+        } as any as Painter;
+        const tileManager = {
+            _source: {minzoom: 3, maxzoom: 22, tileSize: 512},
+            _cache: {max: 10},
+            getTileByID: () => {
+                return new Tile(new OverscaledTileID(zoom, 0, 0, 0, 0), 256);
+            },
+        } as any as TileManager;
+        const terrain = new Terrain(
+            painter,
+            tileManager,
+            {exaggeration: 2} as any as TerrainSpecification,
+        );
 
         const spy = vi.fn();
         terrain.getElevation = spy;
-        terrain.getElevationForLngLat(new LngLat(0, 0));
+        const transform = new MercatorTransform({minZoom: 3, maxZoom: 22, minPitch: 0, maxPitch: 85, renderWorldCopies: true});
+        transform.resize(200, 200);
+        transform.setZoom(zoom);
+        terrain.getElevationForLngLat(new LngLat(0, 0), transform);
 
         expect(spy).toHaveBeenCalled();
-        expect((spy.mock.calls[0][0] as OverscaledTileID).canonical.z).toBe(terrain.tileManager.maxzoom);
+        expect((spy.mock.calls[0][0] as OverscaledTileID).canonical.z).toBe(zoom);
     });
 
     test('getElevationForLngLatZoom with lng less than -180 wraps correctly', () => {

src/render/terrain.ts

@@ -1,25 +1,27 @@
 
-import {type Tile} from '../tile/tile';
 import {mat4, vec2} from 'gl-matrix';
 import {OverscaledTileID} from '../tile/tile_id';
 import {RGBAImage} from '../util/image';
 import {warnOnce} from '../util/util';
 import {Pos3dArray, TriangleIndexArray} from '../data/array_types.g';
 import pos3dAttributes from '../data/pos3d_attributes';
 import {SegmentVector} from '../data/segment';
-import {type Painter} from './painter';
 import {Texture} from '../render/texture';
-import type {Framebuffer} from '../gl/framebuffer';
-import type Point from '@mapbox/point-geometry';
 import {MercatorCoordinate} from '../geo/mercator_coordinate';
 import {TerrainTileManager} from '../tile/terrain_tile_manager';
-import {type TileManager} from '../tile/tile_manager';
 import {EXTENT} from '../data/extent';
-import type {TerrainSpecification} from '@maplibre/maplibre-gl-style-spec';
 import {type LngLat, earthRadius} from '../geo/lng_lat';
 import {Mesh} from './mesh';
 import {isInBoundsForZoomLngLat} from '../util/world_bounds';
 import {NORTH_POLE_Y, SOUTH_POLE_Y} from './subdivision';
+import {coveringTiles} from '../geo/projection/covering_tiles';
+import type Point from '@mapbox/point-geometry';
+import type {Tile} from '../tile/tile';
+import type {Framebuffer} from '../gl/framebuffer';
+import type {TileManager} from '../tile/tile_manager';
+import type {TerrainSpecification} from '@maplibre/maplibre-gl-style-spec';
+import type {Painter} from './painter';
+import type {IReadonlyTransform} from '../geo/transform_interface';
 
 /**
  * @internal
@@ -160,8 +162,7 @@ export class Terrain {
         if (!(x >= 0 && x < extent && y >= 0 && y < extent)) return 0;
         const terrain = this.getTerrainData(tileID);
         const dem = terrain.tile?.dem;
-        if (!dem)
-            return 0;
+        if (!dem) return 0;
 
         const pos = vec2.transformMat4([] as any, [x / extent * EXTENT, y / extent * EXTENT], terrain.u_terrain_matrix);
         const coord = [pos[0] * dem.dim, pos[1] * dem.dim];
@@ -197,8 +198,15 @@ export class Terrain {
      * @param lnglat - the location
      * @returns the elevation
      */
-    getElevationForLngLat(lnglat: LngLat) {
-        return this.getElevationForLngLatZoom(lnglat, this.tileManager.maxzoom);
+    getElevationForLngLat(lnglat: LngLat, transform: IReadonlyTransform) {
+        const terrainCoveringTiles = coveringTiles(transform, {maxzoom: this.tileManager.maxzoom, minzoom: this.tileManager.minzoom, tileSize: 512, terrain: this});
+        let zoom = 0;
+        for (const tile of terrainCoveringTiles) {
+            if (tile.canonical.z > zoom) {
+                zoom = Math.min(tile.canonical.z, this.tileManager.maxzoom);
+            }
+        }
+        return this.getElevationForLngLatZoom(lnglat, zoom);
     }
 
     /**
@@ -241,7 +249,7 @@ export class Terrain {
             sourceTile.needsTerrainPrepare = false;
         }
         // create matrix for lookup in dem data
-        const matrixKey = sourceTile && (sourceTile + sourceTile.tileID.key) + tileID.key;
+        const matrixKey = sourceTile && sourceTile.toString() + sourceTile.tileID.key + tileID.key;
         if (matrixKey && !this._demMatrixCache[matrixKey]) {
             const maxzoom = this.tileManager.getSource().maxzoom;
             let dz = tileID.canonical.z - sourceTile.tileID.canonical.z;

src/ui/camera.test.ts

@@ -2492,7 +2492,8 @@ describe('queryTerrainElevation', () => {
         camera.queryTerrainElevation([1, 2]);
 
         expect(camera.terrain.getElevationForLngLat).toHaveBeenCalledWith(
-            expect.objectContaining({lng: 1, lat: 2,})
+            expect.objectContaining({lng: 1, lat: 2,}),
+            camera.transform
         );
     });
 });

src/ui/camera.ts

@@ -1638,6 +1638,6 @@ export abstract class Camera extends Evented {
         if (!this.terrain) {
             return null;
         }
-        return this.terrain.getElevationForLngLat(LngLat.convert(lngLatLike));
+        return this.terrain.getElevationForLngLat(LngLat.convert(lngLatLike), this.transform);
     }
 }

src/ui/map.ts

@@ -964,7 +964,7 @@ export class Map extends Camera {
 
     calculateCameraOptionsFromTo(from: LngLat, altitudeFrom: number, to: LngLat, altitudeTo?: number): CameraOptions {
         if (altitudeTo == null && this.terrain) {
-            altitudeTo = this.terrain.getElevationForLngLat(to);
+            altitudeTo = this.terrain.getElevationForLngLat(to, this.transform);
         }
         return super.calculateCameraOptionsFromTo(from, altitudeFrom, to, altitudeTo);
     }

src/ui/marker.ts

@@ -579,7 +579,7 @@ export class Marker extends Evented {
         // Read depth framebuffer, getting position of terrain in line of sight to marker
         const terrainDistance = map.terrain.depthAtPoint(this._pos);
         // Transform marker position to clip space
-        const elevation = map.terrain.getElevationForLngLat(this._lngLat);
+        const elevation = map.terrain.getElevationForLngLat(this._lngLat, map.transform);
         const markerDistance = map.transform.lngLatToCameraDepth(this._lngLat, elevation);
         const forgiveness = .006;
         if (markerDistance - terrainDistance < forgiveness) {