fix flickering [skip ci]

3 files changed, 7 insertions, 3 deletions

diff --git a/src/mbgl/renderer/renderer_impl.cpp b/src/mbgl/renderer/renderer_impl.cpp
index 77810f0ca2..ea8ddbee28 100644
--- a/src/mbgl/renderer/renderer_impl.cpp
+++ b/src/mbgl/renderer/renderer_impl.cpp
@@ -367,7 +367,7 @@ void Renderer::Impl::render(const UpdateParameters& updateParameters) {
     auto newPlacement = std::make_unique<Placement>(parameters.state);
     for (auto it = order.rbegin(); it != order.rend(); ++it) {
         if (it->layer.is<RenderSymbolLayer>()) {
-            newPlacement->placeLayer(*it->layer.as<RenderSymbolLayer>(), parameters.debugOptions & MapDebugOptions::Collision);
+            newPlacement->placeLayer(*it->layer.as<RenderSymbolLayer>(), parameters.projMatrix, parameters.debugOptions & MapDebugOptions::Collision);
         }
     }
 
diff --git a/src/mbgl/text/placement.cpp b/src/mbgl/text/placement.cpp
index 39c4a9c79e..d67da53643 100644
--- a/src/mbgl/text/placement.cpp
+++ b/src/mbgl/text/placement.cpp
@@ -34,7 +34,7 @@ uint32_t Placement::maxCrossTileID = 0;
 
 Placement::Placement(const TransformState& state_) : collisionIndex(state_), state(state_) {}
 
-void Placement::placeLayer(RenderSymbolLayer& symbolLayer, bool showCollisionBoxes) {
+void Placement::placeLayer(RenderSymbolLayer& symbolLayer, const mat4& projMatrix, bool showCollisionBoxes) {
     for (RenderTile& renderTile : symbolLayer.renderTiles) {
 
         if (!renderTile.tile.isRenderable()) {
@@ -51,6 +51,10 @@ void Placement::placeLayer(RenderSymbolLayer& symbolLayer, bool showCollisionBox
 
         const float scale = std::pow(2, state.getZoom() - renderTile.id.canonical.z);
 
+        // TODO perf: do this only once for each tile, not once per layer
+        state.matrixFor(renderTile.matrix, renderTile.id);
+        matrix::multiply(renderTile.matrix, projMatrix, renderTile.matrix);
+
         mat4 textLabelPlaneMatrix = getLabelPlaneMatrix(renderTile.matrix,
                 layout.get<TextPitchAlignment>() == style::AlignmentType::Map,
                 layout.get<TextRotationAlignment>() == style::AlignmentType::Map,
diff --git a/src/mbgl/text/placement.hpp b/src/mbgl/text/placement.hpp
index 7e08301bf2..c694e8ef98 100644
--- a/src/mbgl/text/placement.hpp
+++ b/src/mbgl/text/placement.hpp
@@ -39,7 +39,7 @@ namespace mbgl {
     class Placement {
         public:
             Placement(const TransformState&);
-            void placeLayer(RenderSymbolLayer&, bool showCollisionBoxes);
+            void placeLayer(RenderSymbolLayer&, const mat4&, bool showCollisionBoxes);
             bool commit(const Placement& prevPlacement, TimePoint);
             void updateLayerOpacities(RenderSymbolLayer&);
             JointOpacityState getOpacity(uint32_t crossTileSymbolID) const;