Node / meshtastic / Meshtastic-Android / files / androidApp / src / testGoogle / kotlin / org / meshtastic / app / map / offline / pmtiles / WebMercatorTileMathTest.kt

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T8b949e/*

* Copyright (c) 2026 Meshtastic LLC

*

* This program is free software: you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

*

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program. If not, see <https://www.gnu.org/licenses/>.

*/

Tff7b72package T7ee787org.meshtastic.app.map.offline.pmtiles

Tff7b72import T7ee787com.google.android.gms.maps.model.LatLng

Tff7b72import T7ee787kotlin.math.abs

Tff7b72import T7ee787kotlin.test.Test

Tff7b72import T7ee787kotlin.test.assertEquals

Tff7b72import T7ee787kotlin.test.assertTrue

Tff7b72class T56d364WebMercatorTileMathTest Tb4b4b4{

Tf0883e@Test

Tff7b72fun Td2a8ff`zoom 0 has exactly one tile, covering everywhere`Tb4b4b4(Tb4b4b4) Tb4b4b4{

Te6edf3assertEqualsTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4, Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileAtTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff0Tb4b4b4, Te6edf3LatLngTb4b4b4(T79c0ff0.0Tb4b4b4, T79c0ff0.0Tb4b4b4)Tb4b4b4)Tb4b4b4)

Te6edf3assertEqualsTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4, Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileAtTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff0Tb4b4b4, Te6edf3LatLngTb4b4b4(T79c0ff7T79c0ff0.0Tb4b4b4, T79c0ff1T79c0ff7T79c0ff9.0Tb4b4b4)Tb4b4b4)Tb4b4b4)

Tb4b4b4}

Tf0883e@Test

Tff7b72fun Td2a8ff`zoom 1 splits the world into quadrants by hemisphere`Tb4b4b4(Tb4b4b4) Tb4b4b4{

Te6edf3assertEqualsTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4, Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileAtTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff1Tb4b4b4, Te6edf3LatLngTb4b4b4(T79c0ff4T79c0ff5.0Tb4b4b4, Tff7b72-T79c0ff1T79c0ff7T79c0ff0.0Tb4b4b4)Tb4b4b4)Tb4b4b4) T8b949e// NW

Te6edf3assertEqualsTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff1Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4, Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileAtTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff1Tb4b4b4, Te6edf3LatLngTb4b4b4(T79c0ff4T79c0ff5.0Tb4b4b4, T79c0ff1T79c0ff0.0Tb4b4b4)Tb4b4b4)Tb4b4b4) T8b949e// NE

Te6edf3assertEqualsTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff1Tb4b4b4)Tb4b4b4, Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileAtTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff1Tb4b4b4, Te6edf3LatLngTb4b4b4(Tff7b72-T79c0ff4T79c0ff5.0Tb4b4b4, Tff7b72-T79c0ff1T79c0ff7T79c0ff0.0Tb4b4b4)Tb4b4b4)Tb4b4b4) T8b949e// SW

Te6edf3assertEqualsTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff1Tb4b4b4, T79c0ff1Tb4b4b4)Tb4b4b4, Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileAtTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff1Tb4b4b4, Te6edf3LatLngTb4b4b4(Tff7b72-T79c0ff4T79c0ff5.0Tb4b4b4, T79c0ff1T79c0ff0.0Tb4b4b4)Tb4b4b4)Tb4b4b4) T8b949e// SE

Tb4b4b4}

Tf0883e@Test

Tff7b72fun Td2a8ff`the tile origin lands on Web Mercator's own latitude ceiling`Tb4b4b4(Tb4b4b4) Tb4b4b4{

T8b949e// At extent 1, local (0, 0) is the tile's own fx=0, fy=0 corner — the world tile's NW corner.

Tff7b72val Te6edf3corner Tff7b72= Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileLocalToLatLngTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4, Te6edf3extent Tff7b72= T79c0ff1Tb4b4b4, Te6edf3TileCoordTb4b4b4(T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4)

Te6edf3assertEqualsTb4b4b4(Tff7b72-T79c0ff1T79c0ff8T79c0ff0.0Tb4b4b4, Te6edf3cornerTb4b4b4.Te6edf3longitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Te6edf3assertTrueTb4b4b4(Te6edf3absTb4b4b4(Te6edf3cornerTb4b4b4.Te6edf3latitude Tff7b72- Te6edf3WEB_MERCATOR_MAX_LATITUDETb4b4b4) Tff7b72< Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Tb4b4b4}

Tf0883e@Test

Tff7b72fun Td2a8ff`the middle of the world tile is the equator and prime meridian`Tb4b4b4(Tb4b4b4) Tb4b4b4{

Tff7b72val Te6edf3center Tff7b72= Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileLocalToLatLngTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff0Tb4b4b4)Tb4b4b4, Te6edf3extent Tff7b72= T79c0ff2Tb4b4b4, Te6edf3TileCoordTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff1Tb4b4b4)Tb4b4b4)

Te6edf3assertEqualsTb4b4b4(T79c0ff0.0Tb4b4b4, Te6edf3centerTb4b4b4.Te6edf3longitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Te6edf3assertEqualsTb4b4b4(T79c0ff0.0Tb4b4b4, Te6edf3centerTb4b4b4.Te6edf3latitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Tb4b4b4}

Tf0883e@Test

Tff7b72fun Td2a8ff`a deeper tile's local placement matches its own slice of the world`Tb4b4b4(Tb4b4b4) Tb4b4b4{

T8b949e// Tile (2, 3, 1) at zoom 2 spans lon [90, 180); its local midpoint (extent 2, local (1,1)) should land

T8b949e// exactly on that range's own midpoint, 135 — not drift into a neighboring tile's range, which is the bug

T8b949e// off-by-one tile-index math would produce here.

Tff7b72val Te6edf3point Tff7b72= Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileLocalToLatLngTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff2Tb4b4b4, T79c0ff3Tb4b4b4, T79c0ff1Tb4b4b4)Tb4b4b4, Te6edf3extent Tff7b72= T79c0ff2Tb4b4b4, Te6edf3TileCoordTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff1Tb4b4b4)Tb4b4b4)

Te6edf3assertEqualsTb4b4b4(T79c0ff1T79c0ff3T79c0ff5.0Tb4b4b4, Te6edf3pointTb4b4b4.Te6edf3longitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Tb4b4b4}

Tf0883e@Test

Tff7b72fun Td2a8ff`tileFractionalToLatLng agrees with tileLocalToLatLng for the same fractional position`Tb4b4b4(Tb4b4b4) Tb4b4b4{

T8b949e// ContourPoint's own [0,1]x[0,1] convention is exactly local divided by extent, so the two must agree.

Tff7b72val Te6edf3viaLocal Tff7b72= Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileLocalToLatLngTb4b4b4(Te6edf3TileIndexTb4b4b4(T79c0ff2Tb4b4b4, T79c0ff3Tb4b4b4, T79c0ff1Tb4b4b4)Tb4b4b4, Te6edf3extent Tff7b72= T79c0ff4Tb4b4b4, Te6edf3TileCoordTb4b4b4(T79c0ff1Tb4b4b4, T79c0ff3Tb4b4b4)Tb4b4b4)

Tff7b72val Te6edf3viaFractional Tff7b72=

Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileFractionalToLatLngTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff2Tb4b4b4, Te6edf3tileX Tff7b72= T79c0ff3Tb4b4b4, Te6edf3tileY Tff7b72= T79c0ff1Tb4b4b4, Te6edf3fracX Tff7b72= T79c0ff0.25Tb4b4b4, Te6edf3fracY Tff7b72= T79c0ff0.75Tb4b4b4)

Te6edf3assertEqualsTb4b4b4(Te6edf3viaLocalTb4b4b4.Te6edf3longitudeTb4b4b4, Te6edf3viaFractionalTb4b4b4.Te6edf3longitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Te6edf3assertEqualsTb4b4b4(Te6edf3viaLocalTb4b4b4.Te6edf3latitudeTb4b4b4, Te6edf3viaFractionalTb4b4b4.Te6edf3latitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Tb4b4b4}

Tf0883e@Test

Tff7b72fun Td2a8ff`a fractional point at the tile's own center lands on its own midpoint`Tb4b4b4(Tb4b4b4) Tb4b4b4{

T8b949e// Tile (0, 0, 0) is the whole world; its center (0.5, 0.5) is the equator and prime meridian.

Tff7b72val Te6edf3center Tff7b72=

Te6edf3WebMercatorTileMathTb4b4b4.Te6edf3tileFractionalToLatLngTb4b4b4(Te6edf3zoom Tff7b72= T79c0ff0Tb4b4b4, Te6edf3tileX Tff7b72= T79c0ff0Tb4b4b4, Te6edf3tileY Tff7b72= T79c0ff0Tb4b4b4, Te6edf3fracX Tff7b72= T79c0ff0.5Tb4b4b4, Te6edf3fracY Tff7b72= T79c0ff0.5Tb4b4b4)

Te6edf3assertEqualsTb4b4b4(T79c0ff0.0Tb4b4b4, Te6edf3centerTb4b4b4.Te6edf3longitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Te6edf3assertEqualsTb4b4b4(T79c0ff0.0Tb4b4b4, Te6edf3centerTb4b4b4.Te6edf3latitudeTb4b4b4, Te6edf3ABSOLUTE_TOLERANCETb4b4b4)

Tb4b4b4}

Tff7b72private Tff7b72companion Tff7b72object Tb4b4b4{

Tff7b72const Tff7b72val Te6edf3ABSOLUTE_TOLERANCE Tff7b72= T79c0ff1e-6

Tff7b72const Tff7b72val Te6edf3WEB_MERCATOR_MAX_LATITUDE Tff7b72= T79c0ff8T79c0ff5.05112878

Tb4b4b4}

Tb4b4b4}