From 9514b62f1e50e75ff806f2397b37730ba92ce72a Mon Sep 17 00:00:00 2001
From: Lauren Budorick <lauren@mapbox.com>
Date: Tue, 14 Feb 2017 15:12:37 -0800
Subject: [PATCH] Change rendering from per-tile to per-tile vector (allowing
 layers to be grouped)

---
 src/mbgl/renderer/painter.cpp     | 18 ++++++++++++++----
 src/mbgl/renderer/render_item.hpp |  8 +++-----
 src/mbgl/style/style.cpp          | 17 ++++++++---------
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/src/mbgl/renderer/painter.cpp b/src/mbgl/renderer/painter.cpp
index 841413dee1f..796fa371767 100644
--- a/src/mbgl/renderer/painter.cpp
+++ b/src/mbgl/renderer/painter.cpp
@@ -168,8 +168,11 @@ void Painter::render(const Style& style, const FrameData& frame_, View& view, Sp
         annotationSpriteAtlas.upload(context, 0);
 
         for (const auto& item : order) {
-            if (item.bucket && item.bucket->needsUpload()) {
-                item.bucket->upload(context);
+            for (const auto& tileRef : item.tiles) {
+                const auto& bucket = tileRef.get().tile.getBucket(item.layer);
+                if (bucket && bucket->needsUpload()) {
+                    bucket->upload(context);
+                }
             }
         }
     }
@@ -217,6 +220,7 @@ void Painter::render(const Style& style, const FrameData& frame_, View& view, Sp
     if (debug::renderTree) { Log::Info(Event::Render, "{"); indent++; }
 
     // TODO: Correctly compute the number of layers recursively beforehand.
+    // TODO TODO : this actually sounds like the one-order-item-per-layer might *fix* the above todo. Y/N?
     depthRangeSize = 1 - (order.size() + 2) * numSublayers * depthEpsilon;
 
     // - OPAQUE PASS -------------------------------------------------------------------------------
@@ -311,8 +315,14 @@ void Painter::renderPass(PaintParameters& parameters,
             parameters.view.bind();
             context.setDirtyState();
         } else {
-            MBGL_DEBUG_GROUP(layer.baseImpl->id + " - " + util::toString(item.tile->id));
-            item.bucket->render(*this, parameters, layer, *item.tile);
+            for (auto& tileRef : item.tiles) {
+                auto& tile = tileRef.get();
+                MBGL_DEBUG_GROUP(layer.baseImpl->id + " - " + util::toString(tile.id));
+                auto bucket = tile.tile.getBucket(layer);
+                if (bucket) {
+                    bucket->render(*this, parameters, layer, tile);
+                }
+            }
         }
     }
 
diff --git a/src/mbgl/renderer/render_item.hpp b/src/mbgl/renderer/render_item.hpp
index b4b1f4aec23..fc79ef72239 100644
--- a/src/mbgl/renderer/render_item.hpp
+++ b/src/mbgl/renderer/render_item.hpp
@@ -18,14 +18,12 @@ class Source;
 class RenderItem {
 public:
     RenderItem(const style::Layer& layer_,
-               const RenderTile* tile_ = nullptr,
-               Bucket* bucket_ = nullptr)
-        : tile(tile_), bucket(bucket_), layer(layer_) {
+               std::vector<std::reference_wrapper<RenderTile>> tiles_ = {})
+        : layer(layer_), tiles(std::move(tiles_)) {
     }
 
-    const RenderTile* const tile;
-    Bucket* const bucket;
     const style::Layer& layer;
+    std::vector<std::reference_wrapper<RenderTile>> tiles;
 };
 
 class RenderData {
diff --git a/src/mbgl/style/style.cpp b/src/mbgl/style/style.cpp
index b6f14ecf4bd..48a3cd3ab50 100644
--- a/src/mbgl/style/style.cpp
+++ b/src/mbgl/style/style.cpp
@@ -466,9 +466,10 @@ RenderData Style::getRenderData(MapDebugOptions debugOptions, float angle) const
             });
         }
 
-        for (auto& tileRef : sortedTiles) {
-            auto& tile = tileRef.get();
+        for (auto tileIt = sortedTiles.begin(); tileIt != sortedTiles.end(); ++tileIt) {
+            auto& tile = tileIt->get();
             if (!tile.tile.isRenderable()) {
+                sortedTiles.erase(tileIt);
                 continue;
             }
 
@@ -480,9 +481,10 @@ RenderData Style::getRenderData(MapDebugOptions debugOptions, float angle) const
                 // Look back through the buckets we decided to render to find out whether there is
                 // already a bucket from this layer that is a parent of this tile. Tiles are ordered
                 // by zoom level when we obtain them from getTiles().
-                for (auto it = result.order.rbegin(); it != result.order.rend() && (&it->layer == layer.get()); ++it) {
-                    if (tile.tile.id.isChildOf(it->tile->tile.id)) {
+                for (auto it = sortedTiles.rbegin() + (sortedTiles.end() - tileIt); it != sortedTiles.rend(); ++it) {
+                    if (tile.tile.id.isChildOf(it->get().tile.id)) {
                         skip = true;
+                        sortedTiles.erase(--(it.base()));
                         break;
                     }
                 }
@@ -491,12 +493,9 @@ RenderData Style::getRenderData(MapDebugOptions debugOptions, float angle) const
                 }
             }
 
-            auto bucket = tile.tile.getBucket(*layer);
-            if (bucket) {
-                result.order.emplace_back(*layer, &tile, bucket);
-                tile.used = true;
-            }
         }
+
+        result.order.emplace_back(*layer, std::move(sortedTiles));
     }
 
     return result;