From 318ce8616c83d99458482e7c0bd531afe2a2081c Mon Sep 17 00:00:00 2001
From: Rory Fuhrer <rory.fuhrer@orennia.com>
Date: Fri, 3 Oct 2025 11:56:15 -0700
Subject: [PATCH 1/2] Fix that minzoom calcs were using round or ceil instead
 of floor

---
 modules/geo-layers/src/tileset-2d/utils.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/modules/geo-layers/src/tileset-2d/utils.ts b/modules/geo-layers/src/tileset-2d/utils.ts
index c00e2719ac4..14dea715a4b 100644
--- a/modules/geo-layers/src/tileset-2d/utils.ts
+++ b/modules/geo-layers/src/tileset-2d/utils.ts
@@ -285,8 +285,8 @@ export function getTileIndices({
   zoomOffset?: number;
 }) {
   let z = viewport.isGeospatial
-    ? Math.round(viewport.zoom + Math.log2(TILE_SIZE / tileSize)) + zoomOffset
-    : Math.ceil(viewport.zoom) + zoomOffset;
+    ? Math.floor(viewport.zoom + Math.log2(TILE_SIZE / tileSize)) + zoomOffset
+    : Math.floor(viewport.zoom) + zoomOffset;
   if (typeof minZoom === 'number' && Number.isFinite(minZoom) && z < minZoom) {
     if (!extent) {
       return [];

From 079ad418fee17f8505bfaeaee6b6615f5e6d1771 Mon Sep 17 00:00:00 2001
From: Rory Fuhrer <rory.fuhrer@orennia.com>
Date: Tue, 28 Oct 2025 09:13:06 -0700
Subject: [PATCH 2/2] update getTileIndices logic

---
 modules/geo-layers/src/tileset-2d/utils.ts       | 12 +++++++++---
 test/modules/geo-layers/tileset-2d/utils.spec.ts |  8 ++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/modules/geo-layers/src/tileset-2d/utils.ts b/modules/geo-layers/src/tileset-2d/utils.ts
index 14dea715a4b..e188fa6333a 100644
--- a/modules/geo-layers/src/tileset-2d/utils.ts
+++ b/modules/geo-layers/src/tileset-2d/utils.ts
@@ -284,10 +284,16 @@ export function getTileIndices({
   modelMatrixInverse?: Matrix4;
   zoomOffset?: number;
 }) {
+  // This round/ceil operation ensures that tiles are rendered in the same way as Google Maps, Map Libre, etc.
+  // eg. at viewport.zoom = 9.5, you should fetch tiles at z = 10, not z = 9.
   let z = viewport.isGeospatial
-    ? Math.floor(viewport.zoom + Math.log2(TILE_SIZE / tileSize)) + zoomOffset
-    : Math.floor(viewport.zoom) + zoomOffset;
-  if (typeof minZoom === 'number' && Number.isFinite(minZoom) && z < minZoom) {
+    ? Math.round(viewport.zoom + Math.log2(TILE_SIZE / tileSize) + zoomOffset)
+    : Math.ceil(viewport.zoom + zoomOffset);
+
+  // This check doesn't round/ceil and doesn't use the offset. This ensures that tiles are not rendered if the
+  // viewport.zoom is less than minZoom. eg. at viewport.zoom = 9.5 with minZoom = 10 we should not fetch tiles
+  // at z = 10 until viewport.zoom is 10 or greater.
+  if (typeof minZoom === 'number' && Number.isFinite(minZoom) && viewport.zoom < minZoom) {
     if (!extent) {
       return [];
     }
diff --git a/test/modules/geo-layers/tileset-2d/utils.spec.ts b/test/modules/geo-layers/tileset-2d/utils.spec.ts
index b4a7ca2e1f1..6878ae37002 100644
--- a/test/modules/geo-layers/tileset-2d/utils.spec.ts
+++ b/test/modules/geo-layers/tileset-2d/utils.spec.ts
@@ -101,6 +101,14 @@ const TEST_CASES = [
     maxZoom: undefined,
     output: []
   },
+  {
+    title: 'ignore round and offset on minZoom check',
+    viewport: new WebMercatorViewport({longitude: -90, latitude: 45, zoom: 3.5}),
+    zoomOffset: 1,
+    minZoom: 4,
+    maxZoom: undefined,
+    output: []
+  },
   {
     title: 'over zoom',
     viewport: new WebMercatorViewport({