move tile parsing to its own object

src/map/tile_parser.cpp

@@ -0,0 +1,162 @@
+#include <llmr/map/tile_parser.hpp>
+
+#include <llmr/style/style.hpp>
+#include <llmr/renderer/fill_bucket.hpp>
+#include <llmr/renderer/line_bucket.hpp>
+#include <llmr/renderer/point_bucket.hpp>
+#include <llmr/renderer/text_bucket.hpp>
+
+using namespace llmr;
+
+
+TileParser::TileParser(const std::string& data, TileData& tile, const Style& style, GlyphAtlas& glyphAtlas)
+    : data(pbf((const uint8_t *)data.data(), data.size())),
+      tile(tile),
+      style(style),
+      glyphAtlas(glyphAtlas) {
+    parseGlyphs();
+    parseStyleLayers(style.layers);
+}
+
+bool TileParser::obsolete() const {
+    return tile.state == TileData::State::obsolete;
+}
+
+void TileParser::parseGlyphs() {
+    for (const std::pair<std::string, const VectorTileFace> pair : data.faces) {
+        const std::string& name = pair.first;
+        const VectorTileFace& face = pair.second;
+
+        GlyphPositions& rect = rects[name];
+
+        for (const VectorTileGlyph& glyph : face.glyphs) {
+            rect.emplace(glyph.id, glyphAtlas.addGlyph((uint64_t)tile.id, name, glyph));
+        }
+    }
+}
+
+void TileParser::parseStyleLayers(const std::vector<LayerDescription>& layers) {
+    for (const LayerDescription& layer_desc : layers) {
+        // Cancel early when parsing.
+        if (obsolete()) {
+            return;
+        }
+
+        if (layer_desc.child_layer.size()) {
+            // This is a layer group.
+            // TODO: create framebuffer
+            parseStyleLayers(layer_desc.child_layer);
+            // TODO: render framebuffer on previous framebuffer
+        } else {
+            // This is a singular layer. Check if this bucket already exists. If not,
+            // parse this bucket.
+            auto bucket_it = tile.buckets.find(layer_desc.bucket_name);
+            if (bucket_it == tile.buckets.end()) {
+                auto bucket_it = style.buckets.find(layer_desc.bucket_name);
+                if (bucket_it != style.buckets.end()) {
+                    // Only create the new bucket if we have an actual specification
+                    // for it.
+                    std::shared_ptr<Bucket> bucket = createBucket(bucket_it->second);
+                    if (bucket) {
+                        // Bucket creation might fail because the data tile may not
+                        // contain any data that falls into this bucket.
+                        tile.buckets[layer_desc.bucket_name] = bucket;
+                    }
+                } else {
+                    // There is no proper specification for this bucket, even though
+                    // it is referenced in the stylesheet.
+                    fprintf(stderr, "Stylesheet specifies bucket %s, but it is not defined\n", layer_desc.bucket_name.c_str());
+                }
+            }
+        }
+    }
+}
+
+std::shared_ptr<Bucket> TileParser::createBucket(const BucketDescription& bucket_desc) {
+    auto layer_it = data.layers.find(bucket_desc.source_layer);
+    if (layer_it != data.layers.end()) {
+        const VectorTileLayer& layer = layer_it->second;
+        if (bucket_desc.type == BucketType::Fill) {
+            return createFillBucket(layer, bucket_desc);
+        } else if (bucket_desc.type == BucketType::Line) {
+            return createLineBucket(layer, bucket_desc);
+        } else if (bucket_desc.type == BucketType::Point) {
+            return createPointBucket(layer, bucket_desc);
+        } else if (bucket_desc.type == BucketType::Text) {
+            return createTextBucket(layer, bucket_desc);
+        } else {
+            throw std::runtime_error("unknown bucket type");
+        }
+    } else {
+        // The layer specified in the bucket does not exist. Do nothing.
+    }
+
+    return nullptr;
+}
+
+template <class Bucket>
+void TileParser::addBucketFeatures(Bucket& bucket, const VectorTileLayer& layer, const BucketDescription& bucket_desc) {
+    FilteredVectorTileLayer filtered_layer(layer, bucket_desc);
+    for (pbf feature : filtered_layer) {
+        if (obsolete()) return;
+
+        while (feature.next(4)) { // geometry
+            pbf geometry_pbf = feature.message();
+            if (geometry_pbf) {
+                bucket->addGeometry(geometry_pbf);
+            }
+        }
+    }
+}
+
+std::shared_ptr<Bucket> TileParser::createFillBucket(const VectorTileLayer& layer, const BucketDescription& bucket_desc) {
+    std::shared_ptr<FillBucket> bucket = std::make_shared<FillBucket>(
+        tile.fillVertexBuffer, tile.triangleElementsBuffer, tile.lineElementsBuffer, bucket_desc);
+    addBucketFeatures(bucket, layer, bucket_desc);
+    return obsolete() ? nullptr : bucket;
+}
+
+std::shared_ptr<Bucket> TileParser::createLineBucket(const VectorTileLayer& layer, const BucketDescription& bucket_desc) {
+    std::shared_ptr<LineBucket> bucket = std::make_shared<LineBucket>(
+        tile.lineVertexBuffer, tile.triangleElementsBuffer, tile.pointElementsBuffer, bucket_desc);
+    addBucketFeatures(bucket, layer, bucket_desc);
+    return obsolete() ? nullptr : bucket;
+}
+
+std::shared_ptr<Bucket> TileParser::createPointBucket(const VectorTileLayer& layer, const BucketDescription& bucket_desc) {
+    std::shared_ptr<PointBucket> bucket = std::make_shared<PointBucket>(
+        tile.pointVertexBuffer, bucket_desc);
+    addBucketFeatures(bucket, layer, bucket_desc);
+    return obsolete() ? nullptr : bucket;
+}
+
+std::shared_ptr<Bucket> TileParser::createTextBucket(const VectorTileLayer& layer, const BucketDescription& bucket_desc) {
+    // Determine the correct text stack.
+    if (!layer.shaping.size()) {
+        return nullptr;
+    }
+
+    // TODO: currently hardcoded to use the first font stack.
+    const std::map<Value, std::vector<VectorTilePlacement>>& shaping = layer.shaping.begin()->second;
+
+    std::vector<const VectorTileFace *> faces;
+    for (const std::string& face : layer.faces) {
+        auto it = data.faces.find(face);
+        if (it == data.faces.end()) {
+            // This layer references an unknown face.
+            return nullptr;
+        }
+        faces.push_back(&it->second);
+    }
+
+    std::shared_ptr<TextBucket> bucket = std::make_shared<TextBucket>(
+        tile.textVertexBuffer, tile.triangleElementsBuffer, bucket_desc);
+
+    FilteredVectorTileLayer filtered_layer(layer, bucket_desc);
+    for (const pbf& feature_pbf : filtered_layer) {
+        if (obsolete()) return nullptr;
+        bucket->addFeature({ feature_pbf, layer }, faces, shaping);
+    }
+
+    return bucket;
+}