[core] Switch from background to foreground placement

 - Background placement code now just generates static symbol buffers
 - Don't render GeometryTiles until their symbols are loaded. This is necessary for the CrossTileSymbolIndex to successfully prevent flicker.
 - SymbolInstances are transferred to SymbolBucket for use on foreground during collision detection
 - Symbols are sorted on foreground by sorting their index buffer but leaving vertex buffers intact (only works within one segment)
 - Vertical glyphs are generated at same time as horizontal glyphs. `reprojectLineLabels` chooses which one to use at render time and hides the other.
 - Icons are now always represented with a single collision box, even if they're placed along a line (this means their rotation alignment may be wrong, but the approach of representing them with multiple collision boxes wasn't very accurate either).
 - Generate vertices for new debug collision boxes and collision circles
 - Only add symbols within tile boundaries (reduces work, avoids double-draw)
 - Update symbol_projection.cpp to support line label projection calls from CollisionIndex.

1 files changed, 12 insertions, 4 deletions

diff --git a/src/mbgl/layout/symbol_instance.hpp b/src/mbgl/layout/symbol_instance.hpp
index f1df416cd1..827a5dbbdb 100644
--- a/src/mbgl/layout/symbol_instance.hpp
+++ b/src/mbgl/layout/symbol_instance.hpp
@@ -5,6 +5,7 @@
 #include <mbgl/text/collision_feature.hpp>
 #include <mbgl/style/layers/symbol_layer_properties.hpp>
 
+
 namespace mbgl {
 
 class Anchor;
@@ -18,7 +19,6 @@ public:
                    optional<PositionedIcon> shapedIcon,
                    const style::SymbolLayoutProperties::Evaluated&,
                    const float layoutTextSize,
-                   const bool inside,
                    const uint32_t index,
                    const float textBoxScale,
                    const float textPadding,
@@ -26,18 +26,20 @@ public:
                    const std::array<float, 2> textOffset,
                    const float iconBoxScale,
                    const float iconPadding,
-                   style::SymbolPlacementType iconPlacement,
                    const std::array<float, 2> iconOffset,
                    const GlyphPositionMap&,
                    const IndexedSubfeature&,
-                   const std::size_t featureIndex);
+                   const std::size_t featureIndex,
+                   const std::u16string& key,
+                   const float overscaling);
 
     Anchor anchor;
     GeometryCoordinates line;
     uint32_t index;
     bool hasText;
     bool hasIcon;
-    SymbolQuads glyphQuads;
+    SymbolQuads horizontalGlyphQuads;
+    SymbolQuads verticalGlyphQuads;
     optional<SymbolQuad> iconQuad;
     CollisionFeature textCollisionFeature;
     CollisionFeature iconCollisionFeature;
@@ -45,6 +47,12 @@ public:
     std::size_t featureIndex;
     std::array<float, 2> textOffset;
     std::array<float, 2> iconOffset;
+    std::u16string key;
+    bool isDuplicate;
+    optional<size_t> placedTextIndex;
+    optional<size_t> placedVerticalTextIndex;
+    optional<size_t> placedIconIndex;
+    uint32_t crossTileID = 0;
 };
 
 } // namespace mbgl