fix tile loading

src/map/map.cpp

@@ -381,10 +381,13 @@ bool Map::updateTiles() {
 
     // Remove tiles that we definitely don't need, i.e. tiles that are not on
     // the required list.
-    tiles.remove_if([&retain, &changed](const Tile & tile) {
+    std::forward_list<Tile::ID> retain_data;
+    tiles.remove_if([&retain, &retain_data, &changed](const Tile & tile) {
         bool obsolete = std::find(retain.begin(), retain.end(), tile.id) == retain.end();
         if (obsolete) {
             changed = true;
+        } else {
+            retain_data.push_front(tile.data->id);
         }
         return obsolete;
     });
@@ -397,8 +400,18 @@ bool Map::updateTiles() {
     });
 
     // Remove all the expired pointers from the list.
-    tile_data.remove_if([](const std::weak_ptr<TileData>& tile_data) {
-        return tile_data.expired();
+    tile_data.remove_if([&retain_data](const std::weak_ptr<TileData>& tile_data) {
+        const std::shared_ptr<TileData> tile = tile_data.lock();
+        if (!tile) {
+            return true;
+        }
+        bool obsolete = std::find(retain_data.begin(), retain_data.end(), tile->id) == retain_data.end();
+        if (obsolete) {
+            tile->cancel();
+            return true;
+        } else {
+            return false;
+        }
     });
 
     return changed;

src/map/tile_data.cpp

@@ -34,6 +34,7 @@ TileData::TileData(Tile::ID id, const Style& style)
 }
 
 TileData::~TileData() {
+    cancel();
 }
 
 const std::string TileData::toString() const {
@@ -48,13 +49,17 @@ void TileData::request() {
         id.z, id.x, id.y);
 
     // Note: Somehow this feels slower than the change to request_http()
-    std::shared_ptr<TileData> tile = shared_from_this();
+    std::weak_ptr<TileData> weak_tile = shared_from_this();
     platform::Request *request = platform::request_http(url, [=](platform::Response& res) {
-        if (res.code == 200 && tile->state != State::obsolete) {
+        std::shared_ptr<TileData> tile = weak_tile.lock();
+        if (!tile || tile->state == State::obsolete) {
+            // noop. Tile is obsolete and we're now just waiting for the refcount
+            // to drop to zero for destruction.
+        } else if (res.code == 200) {
             tile->state = State::loaded;
             tile->data.swap(res.body);
             tile->parse();
-        } else if (tile->state != State::obsolete) {
+        } else {
             fprintf(stderr, "tile loading failed\n");
         }
     }, []() {
@@ -67,8 +72,6 @@ void TileData::cancel() {
     if (state != State::obsolete) {
         state = State::obsolete;
         platform::cancel_request_http(req);
-    } else {
-        assert((!"logic error? multiple cancelleations"));
     }
 }
 

src/renderer/painter.cpp

@@ -40,7 +40,7 @@ void Painter::setup() {
 
     // Blending
     // We are blending the new pixels *behind* the existing pixels. That way we can
-    // draw front-to-back and use then stencil buffer to cull opaque pixels early.
+    // draw front-to-back and use the depth buffer to cull opaque pixels early.
     glEnable(GL_BLEND);
     glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_ONE);
 
@@ -126,7 +126,7 @@ void Painter::finishClippingMask() {
 void Painter::clear() {
     glStencilMask(0xFF);
     depthMask(true);
-    // glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     glClear(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 }