🐛 zoom-to-mouse: use ptr.worldX/Y + set scroll after setZoom

src/systems/CameraSystem.ts

@@ -52,16 +52,19 @@ export class CameraSystem {
       d:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.D),
     }
 
-    // Scroll wheel zoom — centers the world point under the mouse, then zooms
+    // Scroll wheel zoom — zoom toward mouse pointer
     this.scene.input.on('wheel', (ptr: Phaser.Input.Pointer, _objs: unknown, _dx: number, dy: number) => {
       const newZoom = Phaser.Math.Clamp(cam.zoom - Math.sign(dy) * ZOOM_STEP, MIN_ZOOM, MAX_ZOOM)
       if (newZoom === cam.zoom) return
 
-      // Move the world point under the mouse to the viewport center, then zoom toward it
-      const wp = cam.getWorldPoint(ptr.x, ptr.y)
-      cam.scrollX = wp.x - cam.width  / (2 * newZoom)
-      cam.scrollY = wp.y - cam.height / (2 * newZoom)
+      // ptr.worldX/Y is pre-computed by Phaser and represents the world position under the pointer
+      const worldX = ptr.worldX
+      const worldY = ptr.worldY
+
+      // Apply zoom first, then reposition scroll so worldX stays under ptr.x
       cam.setZoom(newZoom)
+      cam.scrollX = worldX - ptr.x / newZoom
+      cam.scrollY = worldY - ptr.y / newZoom
     })
 
     // Middle-click pan: start on button down