import {describe, test, expect} from 'vitest'; import {CRSWorldCoordinateHelper, identityCrs, type CRS} from './crs.ts'; import {createIdentityCrsAnsweringInside, createPolarStereographicCrs, createRotatedCrs, createWrappingWorldCrs} from '../../util/test/util.ts'; import {mercatorWorldCoordinateHelper} from '../mercator_coordinate.ts'; import {LngLat, earthRadius} from '../lng_lat.ts'; function createSamplePoints(): Array<[number, number]> { return [ [0, 0], [-89, -89], [89, 89], [12.5, 41.9], [-73.98, 40.75], [174.77, -41.29], ]; } /** * Spherical mercator written as a CRS, so its world coordinates can be checked against * the mercator helper's own math. */ function createMercatorAsCrs(): CRS { const halfCircumference = Math.PI * earthRadius; return { name: 'mercator-as-crs', projection: { forward([lng, lat]) { const phi = lat * Math.PI / 180; return [lng * Math.PI / 180 * earthRadius, earthRadius * Math.log(Math.tan(Math.PI / 4 + phi / 2))]; }, inverse([x, y]) { return [x / earthRadius * 180 / Math.PI, (2 * Math.atan(Math.exp(y / earthRadius)) - Math.PI / 2) * 180 / Math.PI]; }, }, tileMatrixSet: {origin: [-halfCircumference, halfCircumference], extentAtZoom0: 2 * halfCircumference}, }; } describe('CRSWorldCoordinateHelper', () => { describe('a converter without an answer outside its tile matrix set', () => { test('maps a position past the east edge to the nearest position inside where inverse returns null', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createIdentityCrsAnsweringInside(null)); expect(worldCoordinateHelper.lngLatFromWorld(1.5, 0.25)).toEqual(new LngLat(90, 45)); }); test('maps a position past the east edge to the nearest position inside where inverse throws', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper({ name: 'test:throwing-outside', projection: { forward: ([lng, lat]) => [lng, lat], inverse([x, y]) { if (Math.abs(x) > 90 || Math.abs(y) > 90) throw new Error(); return [x, y]; }, }, tileMatrixSet: {origin: [-90, 90], extentAtZoom0: 180}, }); expect(worldCoordinateHelper.lngLatFromWorld(1.5, 0.25)).toEqual(new LngLat(90, 45)); }); test('maps a position past the east edge to the nearest position inside where inverse returns NaN', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createIdentityCrsAnsweringInside([NaN, NaN])); expect(worldCoordinateHelper.lngLatFromWorld(1.5, 0.25)).toEqual(new LngLat(90, 45)); }); test('maps a position past the edge of the world to the edge where inverse wraps it to the other side', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createWrappingWorldCrs()); const pastTheEastEdge = worldCoordinateHelper.lngLatFromWorld(0.875, 0.5); expect(pastTheEastEdge.lng).toBeCloseTo(180, 5); expect(pastTheEastEdge.lat).toBeCloseTo(0, 5); }); test('keeps the inverse of a converter that is only approximately invertible', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper({ name: 'test:approximate', projection: {forward: ([lng, lat]) => [lng, lat], inverse: ([x, y]) => [x * 1.0001, y]}, tileMatrixSet: {origin: [-90, 90], extentAtZoom0: 180}, }); expect(worldCoordinateHelper.lngLatFromWorld(0.75, 0.5).lng).toBeCloseTo(45.0045, 6); }); test('keeps the inverse of a converter that never leads back to the position', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper({ name: 'test:imprecise', projection: {forward: ([lng, lat]) => [lng, lat], inverse: ([x, y]) => [x + 1, y]}, tileMatrixSet: {origin: [-90, 90], extentAtZoom0: 180}, }); expect(worldCoordinateHelper.lngLatFromWorld(0.5, 0.5)).toEqual(new LngLat(1, 0)); }); test('throws when inverse has no answer inside the tile matrix set either', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper({...createIdentityCrsAnsweringInside(null), projection: {forward: ([lng, lat]) => [lng, lat], inverse: () => null}}); expect(() => worldCoordinateHelper.lngLatFromWorld(0.5, 0.5)).toThrow('has no answer inside its tile matrix set'); }); }); describe('identity', () => { test('maps the tile 0 square to lng/lat -90..90', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(identityCrs); expect(worldCoordinateHelper.worldFromLngLat(-90, 90)).toMatchObject({x: 0, y: 0}); expect(worldCoordinateHelper.worldFromLngLat(90, -90)).toMatchObject({x: 1, y: 1}); expect(worldCoordinateHelper.worldFromLngLat(0, 0)).toMatchObject({x: 0.5, y: 0.5}); expect(worldCoordinateHelper.worldFromLngLat(45, 45)).toMatchObject({x: 0.75, y: 0.25}); }); test('round trips lng/lat through world coordinates', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(identityCrs); for (const [lng, lat] of createSamplePoints()) { const world = worldCoordinateHelper.worldFromLngLat(lng, lat); const back = worldCoordinateHelper.lngLatFromWorld(world.x, world.y); expect(back).toBeInstanceOf(LngLat); expect(back.lng).toBeCloseTo(lng, 12); expect(back.lat).toBeCloseTo(lat, 12); } }); test('uses a constant meters per world unit equal to the zoom 0 extent', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(identityCrs); expect(worldCoordinateHelper.metersPerWorldUnit(0.5, 0.5)).toBe(180); expect(worldCoordinateHelper.metersPerWorldUnit(0.95, 0.05)).toBe(180); }); test('scales altitude to world z by the zoom 0 extent wherever the location is', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(identityCrs); expect(worldCoordinateHelper.worldZFromAltitude(360, new LngLat(80, 80))).toBe(2); }); test('puts the altitude in z and leaves z at 0 without one', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(identityCrs); expect(worldCoordinateHelper.worldFromLngLat(0, 0).z).toBe(0); expect(worldCoordinateHelper.worldFromLngLat(0, 0, 90).z).toBe(0.5); }); test('clamps a latitude past the poles to the range LngLat accepts, for a position outside the world square', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(identityCrs); const aTenthOfTheSquareNorthOfIt = -0.1; const aTenthOfTheSquareSouthOfIt = 1.1; expect(worldCoordinateHelper.lngLatFromWorld(0.5, aTenthOfTheSquareNorthOfIt).lat).toBe(90); expect(worldCoordinateHelper.lngLatFromWorld(0.5, aTenthOfTheSquareSouthOfIt).lat).toBe(-90); }); test('does not wrap', () => { expect(new CRSWorldCoordinateHelper(identityCrs).wraps).toBe(false); }); }); describe('identity CRS', () => { test('is the identity over lng/lat with tile 0/0/0 spanning -90..90', () => { expect(identityCrs.name).toBe('identity'); expect(identityCrs.projection.forward([12.5, -41.9])).toEqual([12.5, -41.9]); expect(identityCrs.projection.inverse([12.5, -41.9])).toEqual([12.5, -41.9]); expect(identityCrs.tileMatrixSet).toEqual({origin: [-90, 90], extentAtZoom0: 180}); }); }); describe('rotated CRS', () => { test('round trips lng/lat through world coordinates', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createRotatedCrs()); for (const [lng, lat] of createSamplePoints()) { const world = worldCoordinateHelper.worldFromLngLat(lng, lat); const back = worldCoordinateHelper.lngLatFromWorld(world.x, world.y); expect(back.lng).toBeCloseTo(lng, 10); expect(back.lat).toBeCloseTo(lat, 10); } }); test('measures world coordinates from the tile matrix set origin with y growing down', () => { const crs = createRotatedCrs(); const worldCoordinateHelper = new CRSWorldCoordinateHelper(crs); const quarterAcross = 0.25; const threeQuartersDown = 0.75; const [originX, originY] = crs.tileMatrixSet.origin; const extent = crs.tileMatrixSet.extentAtZoom0; const lngLat = worldCoordinateHelper.lngLatFromWorld(quarterAcross, threeQuartersDown); const [x, y] = crs.projection.forward([lngLat.lng, lngLat.lat]); expect(x).toBeCloseTo(originX + quarterAcross * extent, 10); expect(y).toBeCloseTo(originY - threeQuartersDown * extent, 10); }); test('takes the zoom 0 extent as meters per world unit', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createRotatedCrs()); expect(worldCoordinateHelper.metersPerWorldUnit(0.5, 0.5)).toBe(300); }); test('scales altitude to world z by the zoom 0 extent', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createRotatedCrs()); expect(worldCoordinateHelper.worldZFromAltitude(300, new LngLat(0, 0))).toBe(1); }); }); describe('mercator written as a CRS', () => { test('projects lng/lat to the same world coordinates as the mercator helper', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createMercatorAsCrs()); for (const [lng, lat] of [...createSamplePoints(), [-180, -85], [180, 85]]) { const expected = mercatorWorldCoordinateHelper.worldFromLngLat(lng, lat); const actual = worldCoordinateHelper.worldFromLngLat(lng, lat); expect(Math.abs(actual.x - expected.x)).toBeLessThan(1e-12); expect(Math.abs(actual.y - expected.y)).toBeLessThan(1e-12); } }); test('unprojects world coordinates to the same lng/lat as the mercator helper', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createMercatorAsCrs()); for (const [x, y] of [[0.5, 0.5], [0.1, 0.9], [0.999, 0.001], [0.25, 0.75]]) { const expected = mercatorWorldCoordinateHelper.lngLatFromWorld(x, y); const actual = worldCoordinateHelper.lngLatFromWorld(x, y); expect(actual.lng).toBeCloseTo(expected.lng, 10); expect(actual.lat).toBeCloseTo(expected.lat, 10); } }); test('reports the same meters per world unit as the mercator helper at the equator', () => { const worldCoordinateHelper = new CRSWorldCoordinateHelper(createMercatorAsCrs()); expect(worldCoordinateHelper.metersPerWorldUnit(0.5, 0.5)).toBeCloseTo(mercatorWorldCoordinateHelper.metersPerWorldUnit(0.5, 0.5), 6); }); }); describe('latitudeRange', () => { test('runs from where the meridian stretches ten times as much as at the center to the near pole in a north polar CRS', () => { expect(new CRSWorldCoordinateHelper(createPolarStereographicCrs()).latitudeRange).toEqual([-53, 90]); }); test('runs from the near pole to where the meridian stretches ten times as much as at the center in a south polar CRS', () => { const northPolar = createPolarStereographicCrs(); const southPolar: CRS = { ...northPolar, name: 'test:south-polar', projection: { forward([lng, lat]) { return northPolar.projection.forward([lng, -lat]); }, inverse(position) { const [lng, lat] = northPolar.projection.inverse(position); return [lng, -lat]; }, }, }; expect(new CRSWorldCoordinateHelper(southPolar).latitudeRange).toEqual([-90, 53]); }); test('is the whole globe for a projection that stretches no pole that much', () => { expect(new CRSWorldCoordinateHelper(identityCrs).latitudeRange).toEqual([-90, 90]); }); }); });