[core] make symbol sort order more deterministic

3 files changed, 11 insertions, 7 deletions

diff --git a/package.json b/package.json
index 50d5a393d1..742808bbaa 100644
--- a/package.json
+++ b/package.json
@@ -26,7 +26,7 @@
   ],
   "devDependencies": {
     "aws-sdk": "^2.2.21",
-    "mapbox-gl-test-suite": "mapbox/mapbox-gl-test-suite#67fe48d058c23dbb4a8ac36ce0270185da3045a8",
+    "mapbox-gl-test-suite": "mapbox/mapbox-gl-test-suite#7ebad0438ea47721235434f56eb0dba2db66ddb5",
     "node-gyp": "^3.2.1",
     "request": "^2.67.0",
     "tape": "^4.2.2"
diff --git a/src/mbgl/renderer/symbol_bucket.cpp b/src/mbgl/renderer/symbol_bucket.cpp
index 36d285909b..e4fccc22e9 100644
--- a/src/mbgl/renderer/symbol_bucket.cpp
+++ b/src/mbgl/renderer/symbol_bucket.cpp
@@ -31,12 +31,13 @@ namespace mbgl {
 
 SymbolInstance::SymbolInstance(Anchor& anchor, const std::vector<Coordinate>& line,
         const Shaping& shapedText, const PositionedIcon& shapedIcon,
-        const SymbolLayoutProperties& layout, const bool addToBuffers,
+        const SymbolLayoutProperties& layout, const bool addToBuffers, const uint32_t index_,
         const float textBoxScale, const float textPadding, const float textAlongLine,
         const float iconBoxScale, const float iconPadding, const float iconAlongLine,
         const GlyphPositions& face) :
     x(anchor.x),
     y(anchor.y),
+    index(index_),
     hasText(shapedText),
     hasIcon(shapedIcon),
 
@@ -333,7 +334,7 @@ void SymbolBucket::addFeature(const std::vector<std::vector<Coordinate>> &lines,
             // TODO remove the `&& false` when is #1673 implemented
             const bool addToBuffers = (mode == MapMode::Still) || inside || (mayOverlap && false);
 
-            symbolInstances.emplace_back(anchor, line, shapedText, shapedIcon, layout, addToBuffers,
+            symbolInstances.emplace_back(anchor, line, shapedText, shapedIcon, layout, addToBuffers, symbolInstances.size(),
                     textBoxScale, textPadding, textAlongLine,
                     iconBoxScale, iconPadding, iconAlongLine,
                     face);
@@ -382,9 +383,11 @@ void SymbolBucket::placeFeatures(CollisionTile& collisionTile) {
         const float cos = std::cos(collisionTile.config.angle);
 
         std::sort(symbolInstances.begin(), symbolInstances.end(), [sin, cos](SymbolInstance &a, SymbolInstance &b) {
-            const float aRotated = sin * a.x + cos * a.y;
-            const float bRotated = sin * b.x + cos * b.y;
-            return aRotated < bRotated;
+            const int32_t aRotated = sin * a.x + cos * a.y;
+            const int32_t bRotated = sin * b.x + cos * b.y;
+            return aRotated != bRotated ?
+                aRotated < bRotated :
+                a.index > b.index;
         });
     }
 
diff --git a/src/mbgl/renderer/symbol_bucket.hpp b/src/mbgl/renderer/symbol_bucket.hpp
index 7ea5fa05d7..5728cfa28c 100644
--- a/src/mbgl/renderer/symbol_bucket.hpp
+++ b/src/mbgl/renderer/symbol_bucket.hpp
@@ -46,12 +46,13 @@ class SymbolInstance {
     public:
         explicit SymbolInstance(Anchor& anchor, const std::vector<Coordinate>& line,
                 const Shaping& shapedText, const PositionedIcon& shapedIcon,
-                const SymbolLayoutProperties& layout, const bool inside,
+                const SymbolLayoutProperties& layout, const bool inside, const uint32_t index,
                 const float textBoxScale, const float textPadding, const float textAlongLine,
                 const float iconBoxScale, const float iconPadding, const float iconAlongLine,
                 const GlyphPositions& face);
         float x;
         float y;
+        uint32_t index;
         bool hasText;
         bool hasIcon;
         SymbolQuads glyphQuads;