[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, 15 insertions, 18 deletions

diff --git a/src/mbgl/layout/symbol_instance.cpp b/src/mbgl/layout/symbol_instance.cpp
index 02fb800df6..d0398fcd30 100644
--- a/src/mbgl/layout/symbol_instance.cpp
+++ b/src/mbgl/layout/symbol_instance.cpp
@@ -11,7 +11,6 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
                                optional<PositionedIcon> shapedIcon,
                                const SymbolLayoutProperties::Evaluated& layout,
                                const float layoutTextSize,
-                               const bool addToBuffers,
                                const uint32_t index_,
                                const float textBoxScale,
                                const float textPadding,
@@ -19,11 +18,12 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
                                const std::array<float, 2> textOffset_,
                                const float iconBoxScale,
                                const float iconPadding,
-                               const SymbolPlacementType iconPlacement,
                                const std::array<float, 2> iconOffset_,
                                const GlyphPositionMap& positions,
                                const IndexedSubfeature& indexedFeature,
-                               const std::size_t featureIndex_) :
+                               const std::size_t featureIndex_,
+                               const std::u16string& key_,
+                               const float overscaling) :
     anchor(anchor_),
     line(line_),
     index(index_),
@@ -31,25 +31,22 @@ SymbolInstance::SymbolInstance(Anchor& anchor_,
     hasIcon(shapedIcon),
 
     // Create the collision features that will be used to check whether this symbol instance can be placed
-    textCollisionFeature(line_, anchor, shapedTextOrientations.second ?: shapedTextOrientations.first, textBoxScale, textPadding, textPlacement, indexedFeature),
-    iconCollisionFeature(line_, anchor, shapedIcon, iconBoxScale, iconPadding, iconPlacement, indexedFeature),
+    textCollisionFeature(line_, anchor, shapedTextOrientations.first, textBoxScale, textPadding, textPlacement, indexedFeature, overscaling),
+    iconCollisionFeature(line_, anchor, shapedIcon, iconBoxScale, iconPadding, SymbolPlacementType::Point, indexedFeature),
     featureIndex(featureIndex_),
     textOffset(textOffset_),
-    iconOffset(iconOffset_) {
+    iconOffset(iconOffset_),
+    key(key_) {
 
     // Create the quads used for rendering the icon and glyphs.
-    if (addToBuffers) {
-        if (shapedIcon) {
-            iconQuad = getIconQuad(*shapedIcon, layout, layoutTextSize, shapedTextOrientations.first);
-        }
-        if (shapedTextOrientations.first) {
-            auto quads = getGlyphQuads(shapedTextOrientations.first, layout, textPlacement, positions);
-            glyphQuads.insert(glyphQuads.end(), quads.begin(), quads.end());
-        }
-        if (shapedTextOrientations.second) {
-            auto quads = getGlyphQuads(shapedTextOrientations.second, layout, textPlacement, positions);
-            glyphQuads.insert(glyphQuads.end(), quads.begin(), quads.end());
-        }
+    if (shapedIcon) {
+        iconQuad = getIconQuad(*shapedIcon, layout, layoutTextSize, shapedTextOrientations.first);
+    }
+    if (shapedTextOrientations.first) {
+        horizontalGlyphQuads = getGlyphQuads(shapedTextOrientations.first, layout, textPlacement, positions);
+    }
+    if (shapedTextOrientations.second) {
+        verticalGlyphQuads = getGlyphQuads(shapedTextOrientations.second, layout, textPlacement, positions);
     }
 
     if (shapedTextOrientations.first && shapedTextOrientations.second) {