[core] don't break ascent in the overscaled tile phase

We optimize our updateRenderable algorithm by breaking ascent when we've already checked a certain tile. So far, we've compared the UnwrappedTileIDs, but they don't include the overscale component. When ascending through overscaled tile IDs, we've stopped the ascent too early, when we should've kept the search going.

1 files changed, 4 insertions, 5 deletions

diff --git a/src/mbgl/algorithm/update_renderables.hpp b/src/mbgl/algorithm/update_renderables.hpp
index 5fbe0d943f..57cd4f41ec 100644
--- a/src/mbgl/algorithm/update_renderables.hpp
+++ b/src/mbgl/algorithm/update_renderables.hpp
@@ -21,7 +21,7 @@ void updateRenderables(GetTileFn getTile,
                        const IdealTileIDs& idealTileIDs,
                        const Range<uint8_t>& zoomRange,
                        const uint8_t dataTileZoom) {
-    std::unordered_set<UnwrappedTileID> checked;
+    std::unordered_set<OverscaledTileID> checked;
     bool covered;
     int32_t overscaledZ;
 
@@ -85,14 +85,13 @@ void updateRenderables(GetTileFn getTile,
                 // We couldn't find child tiles that entirely cover the ideal tile.
                 for (overscaledZ = dataTileZoom - 1; overscaledZ >= zoomRange.min; --overscaledZ) {
                     const auto parentDataTileID = idealDataTileID.scaledTo(overscaledZ);
-                    const auto parentRenderTileID = parentDataTileID.toUnwrapped();
 
-                    if (checked.find(parentRenderTileID) != checked.end()) {
+                    if (checked.find(parentDataTileID) != checked.end()) {
                         // Break parent tile ascent, this route has been checked by another child
                         // tile before.
                         break;
                     } else {
-                        checked.emplace(parentRenderTileID);
+                        checked.emplace(parentDataTileID);
                     }
 
                     tile = getTile(parentDataTileID);
@@ -117,7 +116,7 @@ void updateRenderables(GetTileFn getTile,
                         parentIsLoaded = tile->isLoaded();
 
                         if (tile->isRenderable()) {
-                            renderTile(parentRenderTileID, *tile);
+                            renderTile(parentDataTileID.toUnwrapped(), *tile);
                             // Break parent tile ascent, since we found one.
                             break;
                         }