[core] Fix render tile ordering when querying sources

2 files changed, 17 insertions, 21 deletions

diff --git a/src/mbgl/style/source_impl.cpp b/src/mbgl/style/source_impl.cpp
index afaa94878c..9d78815627 100644
--- a/src/mbgl/style/source_impl.cpp
+++ b/src/mbgl/style/source_impl.cpp
@@ -207,8 +207,19 @@ std::unordered_map<std::string, std::vector<Feature>> Source::Impl::queryRendere
 
     mapbox::geometry::box<double> box = mapbox::geometry::envelope(queryGeometry);
 
-    for (const auto& tilePtr : renderTiles) {
-        const RenderTile& renderTile = tilePtr.second;
+
+    auto sortRenderTiles = [](const RenderTile& a, const RenderTile& b) {
+        return a.id.canonical.z != b.id.canonical.z ? a.id.canonical.z < b.id.canonical.z :
+               a.id.canonical.y != b.id.canonical.y ? a.id.canonical.y < b.id.canonical.y :
+               a.id.wrap != b.id.wrap ? a.id.wrap < b.id.wrap : a.id.canonical.x < b.id.canonical.x;
+    };
+    std::vector<std::reference_wrapper<const RenderTile>> sortedTiles;
+    std::transform(renderTiles.cbegin(), renderTiles.cend(), std::back_inserter(sortedTiles),
+                   [](const auto& pair) { return std::ref(pair.second); });
+    std::sort(sortedTiles.begin(), sortedTiles.end(), sortRenderTiles);
+
+    for (const auto& renderTileRef : sortedTiles) {
+        const RenderTile& renderTile = renderTileRef.get();
         GeometryCoordinate tileSpaceBoundsMin = TileCoordinate::toGeometryCoordinate(renderTile.id, box.min);
         if (tileSpaceBoundsMin.x >= util::EXTENT || tileSpaceBoundsMin.y >= util::EXTENT) {
             continue;
diff --git a/src/mbgl/tile/tile_id.hpp b/src/mbgl/tile/tile_id.hpp
index 88b01269e5..c95810342b 100644
--- a/src/mbgl/tile/tile_id.hpp
+++ b/src/mbgl/tile/tile_id.hpp
@@ -108,12 +108,7 @@ inline bool CanonicalTileID::operator!=(const CanonicalTileID& rhs) const {
 }
 
 inline bool CanonicalTileID::operator<(const CanonicalTileID& rhs) const {
-    if (z != rhs.z) {
-        return z < rhs.z;
-    } else if (x != rhs.x) {
-        return x < rhs.x;
-    }
-    return y < rhs.y;
+    return z != rhs.z ? z < rhs.z : x != rhs.x ? x < rhs.x : y < rhs.y;
 }
 
 inline bool CanonicalTileID::isChildOf(const CanonicalTileID& parent) const {
@@ -175,10 +170,7 @@ inline bool OverscaledTileID::operator!=(const OverscaledTileID& rhs) const {
 }
 
 inline bool OverscaledTileID::operator<(const OverscaledTileID& rhs) const {
-    if (overscaledZ != rhs.overscaledZ) {
-        return overscaledZ < rhs.overscaledZ;
-    }
-    return canonical < rhs.canonical;
+    return overscaledZ != rhs.overscaledZ ? overscaledZ < rhs.overscaledZ : canonical < rhs.canonical;
 }
 
 inline uint32_t OverscaledTileID::overscaleFactor() const {
@@ -191,11 +183,7 @@ inline bool OverscaledTileID::isChildOf(const OverscaledTileID& rhs) const {
 }
 
 inline OverscaledTileID OverscaledTileID::scaledTo(uint8_t z) const {
-    if (z >= canonical.z) {
-        return { z, canonical };
-    } else {
-        return { z, canonical.scaledTo(z) };
-    }
+    return { z, z >= canonical.z ? canonical : canonical.scaledTo(z) };
 }
 
 inline UnwrappedTileID OverscaledTileID::unwrapTo(int16_t wrap) const {
@@ -223,10 +211,7 @@ inline bool UnwrappedTileID::operator!=(const UnwrappedTileID& rhs) const {
 }
 
 inline bool UnwrappedTileID::operator<(const UnwrappedTileID& rhs) const {
-    if (wrap != rhs.wrap) {
-        return wrap < rhs.wrap;
-    }
-    return canonical < rhs.canonical;
+    return wrap != rhs.wrap ? wrap < rhs.wrap : canonical < rhs.canonical;
 }
 
 inline bool UnwrappedTileID::isChildOf(const UnwrappedTileID& parent) const {