Port global symbol query from GL JS:

 - Symbol querying is now global instead of per-tile
 - Symbols that bleed over tile boundaries no longer missed in queries
 - Symbol results now sorted based on rendering order (ie overlapping symbols change their sort order when a bearing change causes their render order to change)
 - Placement::retainedQueryData now responsible for maintaining symbol querying data for buckets that may no longer be in the TilePyramid.

2 files changed, 6 insertions, 0 deletions

diff --git a/src/mbgl/renderer/buckets/symbol_bucket.cpp b/src/mbgl/renderer/buckets/symbol_bucket.cpp
index 60e8a0b504..3d40a1714d 100644
--- a/src/mbgl/renderer/buckets/symbol_bucket.cpp
+++ b/src/mbgl/renderer/buckets/symbol_bucket.cpp
@@ -200,8 +200,12 @@ void SymbolBucket::sortFeatures(const float angle) {
     text.triangles.clear();
     icon.triangles.clear();
 
+    featureSortOrder = std::make_unique<std::vector<size_t>>();
+    featureSortOrder->reserve(symbolInstanceIndexes.size());
+    
     for (auto i : symbolInstanceIndexes) {
         const SymbolInstance& symbolInstance = symbolInstances[i];
+        featureSortOrder->push_back(symbolInstance.featureIndex);
 
         if (symbolInstance.placedTextIndex) {
             addPlacedSymbol(text.triangles, text.placedSymbols[*symbolInstance.placedTextIndex]);
diff --git a/src/mbgl/renderer/buckets/symbol_bucket.hpp b/src/mbgl/renderer/buckets/symbol_bucket.hpp
index ed8afb052c..e52d18372d 100644
--- a/src/mbgl/renderer/buckets/symbol_bucket.hpp
+++ b/src/mbgl/renderer/buckets/symbol_bucket.hpp
@@ -131,6 +131,8 @@ public:
 
     uint32_t bucketInstanceId = 0;
     bool justReloaded = false;
+    
+    std::shared_ptr<std::vector<size_t>> featureSortOrder;
 };
 
 } // namespace mbgl