6 files changed, 89 insertions, 5 deletions
diff --git a/src/mbgl/renderer/buckets/raster_bucket.cpp b/src/mbgl/renderer/buckets/raster_bucket.cpp
index 3f5879262d..1a0409f456 100644
--- a/src/mbgl/renderer/buckets/raster_bucket.cpp
+++ b/src/mbgl/renderer/buckets/raster_bucket.cpp
@@ -22,7 +22,7 @@ void RasterBucket::upload(gl::Context& context) {
     if (!texture) {
         texture = context.createTexture(*image);
     }
-    if (!vertices.empty()) {
+    if (!segments.empty()) {
         vertexBuffer = context.createVertexBuffer(std::move(vertices));
         indexBuffer = context.createIndexBuffer(std::move(indices));
     }
@@ -45,6 +45,69 @@ void RasterBucket::setImage(std::shared_ptr<PremultipliedImage> image_) {
     uploaded = false;
 }
 
+void RasterBucket::setMask(TileMask&& mask_) {
+    if (mask == mask_) {
+        return;
+    }
+
+    mask = std::move(mask_);
+    clear();
+
+    if (mask == TileMask{ { 0, 0, 0 } }) {
+        // We want to render the full tile, and keeping the segments/vertices/indices empty means
+        // using the global shared buffers for covering the entire tile.
+        return;
+    }
+
+    // Create a new segment so that we will upload (empty) buffers even when there is nothing to
+    // draw for this tile.
+    segments.emplace_back(0, 0);
+
+    constexpr const uint16_t vertexLength = 4;
+
+    // Create the vertex buffer for the specified tile mask.
+    for (const auto& id : mask) {
+        // Create a quad for every masked tile.
+        const int32_t vertexExtent = util::EXTENT >> id.z;
+        const int32_t textureExtent = 32768 >> id.z;
+
+        const Point<int16_t> tlVertex = { static_cast<int16_t>(id.x * vertexExtent),
+                                          static_cast<int16_t>(id.y * vertexExtent) };
+        const Point<int16_t> brVertex = { static_cast<int16_t>(tlVertex.x + vertexExtent),
+                                          static_cast<int16_t>(tlVertex.y + vertexExtent) };
+        const Point<uint16_t> tlTexture = { static_cast<uint16_t>(id.x * textureExtent),
+                                            static_cast<uint16_t>(id.y * textureExtent) };
+        const Point<uint16_t> brTexture = { static_cast<uint16_t>(tlTexture.x + textureExtent),
+                                            static_cast<uint16_t>(tlTexture.y + textureExtent) };
+
+        if (segments.back().vertexLength + vertexLength > std::numeric_limits<uint16_t>::max()) {
+            // Move to a new segments because the old one can't hold the geometry.
+            segments.emplace_back(vertices.vertexSize(), indices.indexSize());
+        }
+
+        vertices.emplace_back(
+            RasterProgram::layoutVertex({ tlVertex.x, tlVertex.y }, { tlTexture.x, tlTexture.y }));
+        vertices.emplace_back(
+            RasterProgram::layoutVertex({ brVertex.x, tlVertex.y }, { brTexture.x, tlTexture.y }));
+        vertices.emplace_back(
+            RasterProgram::layoutVertex({ tlVertex.x, brVertex.y }, { tlTexture.x, brTexture.y }));
+        vertices.emplace_back(
+            RasterProgram::layoutVertex({ brVertex.x, brVertex.y }, { brTexture.x, brTexture.y }));
+
+        auto& segment = segments.back();
+        assert(segment.vertexLength <= std::numeric_limits<uint16_t>::max());
+        const uint16_t offset = segment.vertexLength;
+
+        // 0, 1, 2
+        // 1, 2, 3
+        indices.emplace_back(offset, offset + 1, offset + 2);
+        indices.emplace_back(offset + 1, offset + 2, offset + 3);
+
+        segment.vertexLength += vertexLength;
+        segment.indexLength += 6;
+    }
+}
+
 bool RasterBucket::hasData() const {
     return !!image;
 }
diff --git a/src/mbgl/renderer/buckets/raster_bucket.hpp b/src/mbgl/renderer/buckets/raster_bucket.hpp
index 0b8432eaaf..3800eadec8 100644
--- a/src/mbgl/renderer/buckets/raster_bucket.hpp
+++ b/src/mbgl/renderer/buckets/raster_bucket.hpp
@@ -5,6 +5,7 @@
 #include <mbgl/gl/vertex_buffer.hpp>
 #include <mbgl/programs/raster_program.hpp>
 #include <mbgl/renderer/bucket.hpp>
+#include <mbgl/renderer/tile_mask.hpp>
 #include <mbgl/util/image.hpp>
 #include <mbgl/util/mat4.hpp>
 #include <mbgl/util/optional.hpp>
@@ -21,8 +22,11 @@ public:
 
     void clear();
     void setImage(std::shared_ptr<PremultipliedImage>);
+    void setMask(TileMask&&);
+
     std::shared_ptr<PremultipliedImage> image;
     optional<gl::Texture> texture;
+    TileMask mask{ { 0, 0, 0 } };
 
     // Bucket specific vertices are used for Image Sources only
     // Raster Tile Sources use the default buffers from Painter
diff --git a/src/mbgl/renderer/layers/render_raster_layer.cpp b/src/mbgl/renderer/layers/render_raster_layer.cpp
index 367fd91fa5..06616d90e5 100644
--- a/src/mbgl/renderer/layers/render_raster_layer.cpp
+++ b/src/mbgl/renderer/layers/render_raster_layer.cpp
@@ -135,10 +135,19 @@ void RenderRasterLayer::render(PaintParameters& parameters, RenderSource* source
             parameters.context.bindTexture(*bucket.texture, 0, gl::TextureFilter::Linear);
             parameters.context.bindTexture(*bucket.texture, 1, gl::TextureFilter::Linear);
 
-            draw(tile.matrix,
-                 parameters.staticData.rasterVertexBuffer,
-                 parameters.staticData.quadTriangleIndexBuffer,
-                 parameters.staticData.rasterSegments);
+            if (bucket.vertexBuffer && bucket.indexBuffer && !bucket.segments.empty()) {
+                // Draw only the parts of the tile that aren't drawn by another tile in the layer.
+                draw(tile.matrix,
+                     *bucket.vertexBuffer,
+                     *bucket.indexBuffer,
+                     bucket.segments);
+            } else {
+                // Draw the full tile.
+                draw(tile.matrix,
+                     parameters.staticData.rasterVertexBuffer,
+                     parameters.staticData.quadTriangleIndexBuffer,
+                     parameters.staticData.rasterSegments);
+            }
         }
     }
 }
diff --git a/src/mbgl/renderer/render_tile.cpp b/src/mbgl/renderer/render_tile.cpp
index 4e924331cc..c9912f0563 100644
--- a/src/mbgl/renderer/render_tile.cpp
+++ b/src/mbgl/renderer/render_tile.cpp
@@ -52,6 +52,10 @@ mat4 RenderTile::translatedClipMatrix(const std::array<float, 2>& translation,
     return translateVtxMatrix(nearClippedMatrix, translation, anchor, state, false);
 }
 
+void RenderTile::setMask(TileMask&& mask) {
+    tile.setMask(std::move(mask));
+}
+
 void RenderTile::startRender(PaintParameters& parameters) {
     tile.upload(parameters.context);
 
diff --git a/src/mbgl/renderer/render_tile.hpp b/src/mbgl/renderer/render_tile.hpp
index d5ed4f0018..b498972f5c 100644
--- a/src/mbgl/renderer/render_tile.hpp
+++ b/src/mbgl/renderer/render_tile.hpp
@@ -4,6 +4,7 @@
 #include <mbgl/util/mat4.hpp>
 #include <mbgl/util/clip_id.hpp>
 #include <mbgl/style/types.hpp>
+#include <mbgl/renderer/tile_mask.hpp>
 
 #include <array>
 
@@ -36,6 +37,7 @@ public:
                               style::TranslateAnchorType anchor,
                               const TransformState&) const;
 
+    void setMask(TileMask&&);
     void startRender(PaintParameters&);
     void finishRender(PaintParameters&);
 
diff --git a/src/mbgl/renderer/sources/render_raster_source.cpp b/src/mbgl/renderer/sources/render_raster_source.cpp
index 910a812f05..cbd874f647 100644
--- a/src/mbgl/renderer/sources/render_raster_source.cpp
+++ b/src/mbgl/renderer/sources/render_raster_source.cpp
@@ -1,6 +1,7 @@
 #include <mbgl/renderer/sources/render_raster_source.hpp>
 #include <mbgl/renderer/render_tile.hpp>
 #include <mbgl/tile/raster_tile.hpp>
+#include <mbgl/algorithm/update_tile_masks.hpp>
 
 namespace mbgl {
 
@@ -57,6 +58,7 @@ void RenderRasterSource::update(Immutable<style::Source::Impl> baseImpl_,
 }
 
 void RenderRasterSource::startRender(PaintParameters& parameters) {
+    algorithm::updateTileMasks(tilePyramid.getRenderTiles());
     tilePyramid.startRender(parameters);
 }