[core] Only run placement for first layer per SymbolBucket

Native version of mapbox/mapbox-gl-js#6548.
Port of mapbox/mapbox-gl-js#6550.
Prevents symbols that share the same layout properties from colliding against each other.

Bump GL JS pin to get regression test.
Rename "bucketName" -> "bucketLeaderID" to make it clearer what it represents.

2 files changed, 10 insertions, 10 deletions

diff --git a/src/mbgl/geometry/feature_index.cpp b/src/mbgl/geometry/feature_index.cpp
index 520fd313a2..fdd9558d0b 100644
--- a/src/mbgl/geometry/feature_index.cpp
+++ b/src/mbgl/geometry/feature_index.cpp
@@ -25,14 +25,14 @@ FeatureIndex::FeatureIndex(std::unique_ptr<const GeometryTileData> tileData_)
 void FeatureIndex::insert(const GeometryCollection& geometries,
                           std::size_t index,
                           const std::string& sourceLayerName,
-                          const std::string& bucketName) {
+                          const std::string& bucketLeaderID) {
     for (const auto& ring : geometries) {
         auto envelope = mapbox::geometry::envelope(ring);
         if (envelope.min.x < util::EXTENT &&
             envelope.min.y < util::EXTENT &&
             envelope.max.x >= 0 &&
             envelope.max.y >= 0) {
-            grid.insert(IndexedSubfeature(index, sourceLayerName, bucketName, sortIndex++),
+            grid.insert(IndexedSubfeature(index, sourceLayerName, bucketLeaderID, sortIndex++),
                         {convertPoint<float>(envelope.min), convertPoint<float>(envelope.max)});
         }
     }
@@ -141,7 +141,7 @@ void FeatureIndex::addFeature(
     std::unique_ptr<GeometryTileLayer> sourceLayer;
     std::unique_ptr<GeometryTileFeature> geometryTileFeature;
 
-    for (const std::string& layerID : bucketLayerIDs.at(indexedFeature.bucketName)) {
+    for (const std::string& layerID : bucketLayerIDs.at(indexedFeature.bucketLeaderID)) {
         const RenderLayer* renderLayer = getRenderLayer(layerID);
         if (!renderLayer) {
             continue;
@@ -190,8 +190,8 @@ optional<GeometryCoordinates> FeatureIndex::translateQueryGeometry(
     return translated;
 }
 
-void FeatureIndex::setBucketLayerIDs(const std::string& bucketName, const std::vector<std::string>& layerIDs) {
-    bucketLayerIDs[bucketName] = layerIDs;
+void FeatureIndex::setBucketLayerIDs(const std::string& bucketLeaderID, const std::vector<std::string>& layerIDs) {
+    bucketLayerIDs[bucketLeaderID] = layerIDs;
 }
 
 } // namespace mbgl
diff --git a/src/mbgl/geometry/feature_index.hpp b/src/mbgl/geometry/feature_index.hpp
index cc91791d36..739c1f282f 100644
--- a/src/mbgl/geometry/feature_index.hpp
+++ b/src/mbgl/geometry/feature_index.hpp
@@ -25,7 +25,7 @@ public:
     IndexedSubfeature(std::size_t index_, std::string sourceLayerName_, std::string bucketName_, size_t sortIndex_)
         : index(index_)
         , sourceLayerName(std::move(sourceLayerName_))
-        , bucketName(std::move(bucketName_))
+        , bucketLeaderID(std::move(bucketName_))
         , sortIndex(sortIndex_)
         , bucketInstanceId(0)
     {}
@@ -34,13 +34,13 @@ public:
     IndexedSubfeature(const IndexedSubfeature& other, uint32_t bucketInstanceId_)
         : index(other.index)
         , sourceLayerName(other.sourceLayerName)
-        , bucketName(other.bucketName)
+        , bucketLeaderID(other.bucketLeaderID)
         , sortIndex(other.sortIndex)
         , bucketInstanceId(bucketInstanceId_)
     {}
     size_t index;
     std::string sourceLayerName;
-    std::string bucketName;
+    std::string bucketLeaderID;
     size_t sortIndex;
 
     // Only used for symbol features
@@ -53,7 +53,7 @@ public:
 
     const GeometryTileData* getData() { return tileData.get(); }
     
-    void insert(const GeometryCollection&, std::size_t index, const std::string& sourceLayerName, const std::string& bucketName);
+    void insert(const GeometryCollection&, std::size_t index, const std::string& sourceLayerName, const std::string& bucketLeaderID);
 
     void query(
             std::unordered_map<std::string, std::vector<Feature>>& result,
@@ -74,7 +74,7 @@ public:
             const float bearing,
             const float pixelsToTileUnits);
 
-    void setBucketLayerIDs(const std::string& bucketName, const std::vector<std::string>& layerIDs);
+    void setBucketLayerIDs(const std::string& bucketLeaderID, const std::vector<std::string>& layerIDs);
     
     std::unordered_map<std::string, std::vector<Feature>> lookupSymbolFeatures(
            const std::vector<IndexedSubfeature>& symbolFeatures,