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bradhbradh
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feat: initial MVT ST_TileEnvelope implementation
This is similar to the PostGIS ST_TileEnvelope function, but only supports the standard (EPSG:3857) geometry, and does not support additional margins.
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‎src/spatial/modules/CMakeLists.txt‎

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endif()
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add_subdirectory(osm)
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add_subdirectory(shapefile)
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add_subdirectory(mvt)
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set(EXTENSION_SOURCES
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${EXTENSION_SOURCES}

‎src/spatial/modules/mvt/CMakeLists.txt‎

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set(EXTENSION_SOURCES
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${EXTENSION_SOURCES}
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${CMAKE_CURRENT_SOURCE_DIR}/mvt_module.cpp
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PARENT_SCOPE
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)

‎src/spatial/modules/mvt/mvt_module.cpp‎

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// Mapbox Vector Tiles (MVT) implementation
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#include "spatial/modules/mvt/mvt_module.hpp"
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#include "duckdb/common/vector_operations/generic_executor.hpp"
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#include "spatial/geometry/geometry_serialization.hpp"
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#include "spatial/geometry/sgl.hpp"
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#include "spatial/spatial_types.hpp"
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#include <spatial/util/function_builder.hpp>
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namespace duckdb {
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namespace {
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// ######################################################################################################################
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// Util
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// ######################################################################################################################
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//======================================================================================================================
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// LocalState
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//======================================================================================================================
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class LocalState final : public FunctionLocalState {
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public:
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explicit LocalState(ClientContext &context) : arena(BufferAllocator::Get(context)), allocator(arena) {
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}
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static unique_ptr<FunctionLocalState> Init(ExpressionState &state, const BoundFunctionExpression &expr,
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FunctionData *bind_data);
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static LocalState &ResetAndGet(ExpressionState &state);
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string_t Serialize(Vector &vector, const sgl::geometry &geom);
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GeometryAllocator &GetAllocator() {
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return allocator;
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}
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private:
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ArenaAllocator arena;
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GeometryAllocator allocator;
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};
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unique_ptr<FunctionLocalState> LocalState::Init(ExpressionState &state, const BoundFunctionExpression &expr,
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FunctionData *bind_data) {
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return make_uniq_base<FunctionLocalState, LocalState>(state.GetContext());
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}
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LocalState &LocalState::ResetAndGet(ExpressionState &state) {
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auto &local_state = ExecuteFunctionState::GetFunctionState(state)->Cast<LocalState>();
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local_state.arena.Reset();
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return local_state;
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}
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string_t LocalState::Serialize(Vector &vector, const sgl::geometry &geom) {
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const auto size = Serde::GetRequiredSize(geom);
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auto blob = StringVector::EmptyString(vector, size);
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Serde::Serialize(geom, blob.GetDataWriteable(), size);
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blob.Finalize();
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return blob;
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}
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} // namespace
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namespace {
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struct ST_TileEnvelope {
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static constexpr double RADIUS = 6378137.0;
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static constexpr double PI = 3.141592653589793;
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static constexpr double CIRCUMFERENCE = 2 * PI * RADIUS;
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static void ExecuteWebMercator(DataChunk &args, ExpressionState &state, Vector &result) {
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auto &lstate = LocalState::ResetAndGet(state);
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TernaryExecutor::Execute<int32_t, int32_t, int32_t, string_t>(
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args.data[0], args.data[1], args.data[2], result, args.size(),
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[&](int32_t tile_zoom, int32_t tile_x, int32_t tile_y) {
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validate_tile_zoom_argument(tile_zoom);
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uint32_t zoom_extent = 1u << tile_zoom;
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validate_tile_index_arguments(zoom_extent, tile_x, tile_y);
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sgl::geometry bbox;
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get_tile_bbox(lstate.GetAllocator(), zoom_extent, tile_x, tile_y, bbox);
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return lstate.Serialize(result, bbox);
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});
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}
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static void validate_tile_zoom_argument(int32_t tile_zoom) {
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if ((tile_zoom < 0) || (tile_zoom > 30)) {
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throw InvalidInputException("ST_TileEnvelope: tile_zoom must be in the range [0,30]");
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}
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}
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static void validate_tile_index_arguments(uint32_t zoom_extent, int32_t tile_x, int32_t tile_y) {
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if ((tile_x < 0) || ((uint32_t)tile_x >= zoom_extent)) {
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throw InvalidInputException("ST_TileEnvelope: tile_x is out of range for specified tile_zoom");
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}
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if ((tile_y < 0) || ((uint32_t)tile_y >= zoom_extent)) {
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throw InvalidInputException("ST_TileEnvelope: tile_y is out of range for specified tile_zoom");
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}
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}
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static void get_tile_bbox(GeometryAllocator &allocator, uint32_t zoom_extent,
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int32_t tile_x, int32_t tile_y, sgl::geometry &bbox) {
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double single_tile_width = CIRCUMFERENCE / zoom_extent;
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double single_tile_height = CIRCUMFERENCE / zoom_extent;
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double tile_left = get_tile_left(tile_x, single_tile_width);
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double tile_right = tile_left + single_tile_width;
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double tile_top = get_tile_top(tile_y, single_tile_height);
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double tile_bottom = tile_top - single_tile_height;
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sgl::polygon::init_from_bbox(allocator, tile_left, tile_bottom, tile_right, tile_top, bbox);
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}
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static double get_tile_left(uint32_t tile_x, double single_tile_width) {
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return -0.5 * CIRCUMFERENCE + (tile_x * single_tile_width);
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}
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static double get_tile_top(uint32_t tile_y, double single_tile_height) {
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return 0.5 * CIRCUMFERENCE - (tile_y * single_tile_height);
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}
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//------------------------------------------------------------------------------------------------------------------
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// Documentation
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//------------------------------------------------------------------------------------------------------------------
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static constexpr auto DESCRIPTION = R"(
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The `ST_TileEnvelope` scalar function generates tile envelope rectangular polygons from specified zoom level and tile indices.
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This is used in MVT generation to select the features corresponding to the tile extent. The envelope is in the Web Mercator
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coordinate reference system (EPSG:3857). The tile pyramid starts at zoom level 0, corresponding to a single tile for the
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world. Each zoom level doubles the number of tiles in each direction, such that zoom level 1 is 2 tiles wide by 2 tiles high,
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zoom level 2 is 4 tiles wide by 4 tiles high, and so on. Tile indices start at `[x=0, y=0]` at the top left, and increase
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down and right. For example, at zoom level 2, the top right tile is `[x=3, y=0]`, the bottom left tile is `[x=0, y=3]`, and
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the bottom right is `[x=3, y=3]`.
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```sql
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SELECT ST_TileEnvelope(2, 3, 1);
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```
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)";
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static constexpr auto EXAMPLE = R"(
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SELECT ST_TileEnvelope(2, 3, 1);
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┌───────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ st_tileenvelope(2, 3, 1) │
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│ geometry │
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├───────────────────────────────────────────────────────────────────────────────────────────────────────────┤
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│ POLYGON ((1.00188E+07 0, 1.00188E+07 1.00188E+07, 2.00375E+07 1.00188E+07, 2.00375E+07 0, 1.00188E+07 0)) │
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└───────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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)";
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//------------------------------------------------------------------------------------------------------------------
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// Register
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//------------------------------------------------------------------------------------------------------------------
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static void Register(DatabaseInstance &db) {
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FunctionBuilder::RegisterScalar(db, "ST_TileEnvelope", [](ScalarFunctionBuilder &func) {
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func.AddVariant([](ScalarFunctionVariantBuilder &variant) {
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variant.AddParameter("tile_zoom", LogicalType::INTEGER);
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variant.AddParameter("tile_x", LogicalType::INTEGER);
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variant.AddParameter("tile_y", LogicalType::INTEGER);
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variant.SetReturnType(GeoTypes::GEOMETRY());
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variant.SetInit(LocalState::Init);
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variant.SetFunction(ExecuteWebMercator);
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});
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func.SetDescription(DESCRIPTION);
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func.SetExample(EXAMPLE);
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func.SetTag("ext", "spatial");
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func.SetTag("category", "conversion");
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});
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}
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};
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} // namespace
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//------------------------------------------------------------------------------
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// Register
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//------------------------------------------------------------------------------
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void RegisterMapboxVectorTileModule(DatabaseInstance &db) {
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ST_TileEnvelope::Register(db);
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};
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} // namespace duckdb

‎src/spatial/modules/mvt/mvt_module.hpp‎

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#pragma once
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namespace duckdb {
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class DatabaseInstance;
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void RegisterMapboxVectorTileModule(DatabaseInstance &db);
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} // namespace duckdb

‎src/spatial/spatial_extension.cpp‎

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#if SPATIAL_USE_GEOS
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#include "spatial/modules/geos/geos_module.hpp"
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#endif
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#include "spatial/modules/mvt/mvt_module.hpp"
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#include "operators/spatial_operator_extension.hpp"
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#include "spatial/modules/main/spatial_functions.hpp"
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#include "spatial/modules/osm/osm_module.hpp"
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#endif
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RegisterOSMModule(instance);
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RegisterShapefileModule(instance);
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RegisterMapboxVectorTileModule(instance);
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RTreeModule::RegisterIndex(instance);
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RTreeModule::RegisterIndexPragmas(instance);

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