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Properly clip lines so that we don't get crazy coords with long linestrings (relative to tile coords)

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This commit is contained in:
Daniel Patterson 2016-03-21 18:13:31 -07:00 committed by Patrick Niklaus
parent fc027417d8
commit 08e56956d6
1 changed files with 49 additions and 6 deletions
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47
src/engine/plugins/tile.cpp
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@ -3,6 +3,10 @@
#include "util/coordinate_calculation.hpp"
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/geometries.hpp>
#include <protozero/varint.hpp>
#include <protozero/pbf_writer.hpp>
@ -23,6 +27,7 @@ namespace detail
{
// Vector tiles are 4096 virtual pixels on each side
const constexpr double VECTOR_TILE_EXTENT = 4096.0;
const constexpr double VECTOR_TILE_BUFFER = 128.0;
// Simple container class for WSG84 coordinates
template <typename T> struct Point final
@ -67,6 +72,14 @@ struct point_type_i final
using FixedLine = std::vector<detail::Point<std::int32_t>>;
using FloatLine = std::vector<detail::Point<double>>;
typedef boost::geometry::model::point<double, 2, boost::geometry::cs::cartesian> point_t;
typedef boost::geometry::model::linestring<point_t> linestring_t;
typedef boost::geometry::model::box<point_t> box_t;
typedef boost::geometry::model::multi_linestring<linestring_t> multi_linestring_t;
const static box_t clip_box({-detail::VECTOR_TILE_BUFFER, -detail::VECTOR_TILE_BUFFER},
{detail::VECTOR_TILE_EXTENT + detail::VECTOR_TILE_BUFFER,
detail::VECTOR_TILE_EXTENT + detail::VECTOR_TILE_BUFFER});
// from mapnik-vector-tile
// Encodes a linestring using protobuf zigzag encoding
inline bool encodeLinestring(const FixedLine &line,
@ -111,7 +124,9 @@ FixedLine coordinatesToTileLine(const util::Coordinate start,
static_cast<double>(util::toFloating(start.lat)));
geo_line.emplace_back(static_cast<double>(util::toFloating(target.lon)),
static_cast<double>(util::toFloating(target.lat)));
FixedLine tile_line;
linestring_t unclipped_line;
for (auto const &pt : geo_line)
{
double px_merc = pt.x * mercator::DEGREE_TO_PX;
@ -123,8 +138,29 @@ FixedLine coordinatesToTileLine(const util::Coordinate start,
const auto py = std::round(
((tile_bbox.maxy - py_merc) * mercator::TILE_SIZE / tile_bbox.height()) *
detail::VECTOR_TILE_EXTENT / util::coordinate_calculation::mercator::TILE_SIZE);
tile_line.emplace_back(px, py);
boost::geometry::append(unclipped_line, point_t(px, py));
}
multi_linestring_t clipped_line;
boost::geometry::intersection(clip_box, unclipped_line, clipped_line);
FixedLine tile_line;
// b::g::intersection might return a line with one point if the
// original line was very short and coords were dupes
if (!clipped_line.empty() && clipped_line[0].size() == 2)
{
if (clipped_line[0].size() == 2)
{
for (const auto &p : clipped_line[0])
{
tile_line.emplace_back(p.get<0>(), p.get<1>());
}
}
}
return tile_line;
}
}
@ -317,6 +353,7 @@ Status TilePlugin::HandleRequest(const api::TileParameters &parameters, std::str
duration); // duration value offset
}
{
// Encode the geometry for the feature
protozero::packed_field_uint32 geometry(feature_writer, 4);
encodeLinestring(tile_line, geometry, start_x, start_y);
@ -334,9 +371,12 @@ Status TilePlugin::HandleRequest(const api::TileParameters &parameters, std::str
static_cast<std::uint32_t>(round(length / forward_weight * 10 * 3.6));
auto tile_line = coordinatesToTileLine(a, b, tile_bbox);
if (!tile_line.empty())
{
encode_tile_line(tile_line, speed_kmh, weight_offsets[forward_weight],
forward_datasource, start_x, start_y);
}
}
// Repeat the above for the coordinates reversed and using the `reverse`
// properties
@ -350,11 +390,14 @@ Status TilePlugin::HandleRequest(const api::TileParameters &parameters, std::str
static_cast<std::uint32_t>(round(length / reverse_weight * 10 * 3.6));
auto tile_line = coordinatesToTileLine(b, a, tile_bbox);
if (!tile_line.empty())
{
encode_tile_line(tile_line, speed_kmh, weight_offsets[reverse_weight],
reverse_datasource, start_x, start_y);
}
}
}
}
// Field id 3 is the "keys" attribute
// We need two "key" fields, these are referred to with 0 and 1 (their array indexes)