From 95667c159e391233c4836163e847426bd8d8ee6b Mon Sep 17 00:00:00 2001
From: Andrew Olsen <andrew.olsen@koordinates.com>
Date: Fri, 5 Apr 2024 08:00:24 +1100
Subject: [PATCH] Fix for #3935 - add test, update CHANGELOG

---
 CHANGELOG.md               |  2 +-
 src/render/terrain.test.ts | 22 +++++++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5b3f25174e..87b253d03d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 - Added const enum for actor messages to improve readability and maintainability. In tsconfig.json, `isolatedModules` flag is set to false in favor of generated JS size. ([#3879](https://github.com/maplibre/maplibre-gl-js/issues/3879))
 
 ### 🐞 Bug fixes
-- _...Add new stuff here..._
+- Fix different unwanted panning changes at the end of a panning motion, that happen on a large screen ([#3935](https://github.com/maplibre/maplibre-gl-js/issues/3935))
 
 ## 4.1.2
 
diff --git a/src/render/terrain.test.ts b/src/render/terrain.test.ts
index 22c4d4250a..befcab698e 100644
--- a/src/render/terrain.test.ts
+++ b/src/render/terrain.test.ts
@@ -65,14 +65,14 @@ describe('Terrain', () => {
 
     });
 
-    const setupMercatorOverflow = () => {
+    const setupMercatorOverflow = (pixelRatio: number = 1) => {
         const WORLD_WIDTH = 4;
         const painter = {
             context: new Context(gl),
             width: WORLD_WIDTH,
             height: 1,
-            pixelRatio: 1,
             maybeDrawDepthAndCoords: jest.fn(),
+            pixelRatio,
         } as any as Painter;
         const sourceCache = {} as SourceCache;
         const terrain = new Terrain(painter, sourceCache, {} as any as TerrainSpecification);
@@ -91,7 +91,7 @@ describe('Terrain', () => {
             rgba[0] = 0;
             rgba[1] = 0;
             rgba[2] = 0;
-            rgba[3] = 255 - x;
+            rgba[3] = 255 - x / pixelRatio;
         });
         return terrain;
     };
@@ -122,6 +122,22 @@ describe('Terrain', () => {
             expect(terrain.painter.maybeDrawDepthAndCoords).toHaveBeenCalled();
         });
 
+    test(
+        'pointCoordinate should respect painter.pixelRatio',
+        () => {
+            const terrain = setupMercatorOverflow(2);
+
+            let pointX = 0;
+            let coordinate = terrain.pointCoordinate(new Point(pointX, 0));
+            expect(coordinate.x).toBe(-1);
+            expect(terrain.painter.maybeDrawDepthAndCoords).toHaveBeenCalled();
+
+            pointX = 3;
+            coordinate = terrain.pointCoordinate(new Point(pointX, 0));
+            expect(coordinate.x).toBe(2);
+            expect(terrain.painter.maybeDrawDepthAndCoords).toHaveBeenCalled();
+        });
+
     test('Calculate tile minimum and maximum elevation', () => {
         const tileID = new OverscaledTileID(5, 0, 5, 17, 11);
         const tile = new Tile(tileID, 256);