84 lines
2.1 KiB
Markdown
84 lines
2.1 KiB
Markdown
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# geometry.hpp
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Provides header-only, generic C++ interfaces for geometry types, geometry collections, and features.
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- `mapbox::geometry::point`
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- `mapbox::geometry::multi_point`
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- `mapbox::geometry::line_string`
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- `mapbox::geometry::multi_line_string`
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- `mapbox::geometry::polygon`
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- `mapbox::geometry::multi_polygon`
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- `mapbox::geometry::geometry_collection`
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- `mapbox::geometry::feature` (experimental)
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### Design
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These types are designed to be easy to parse and serialize to [GeoJSON](http://geojson.org/).
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They should also be a robust and high performance container for data processing and conversion.
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### Goals
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- Header-only
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- Fast compile
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- c++11/c++14 compatibility
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- No external dependencies for usage of core types (point, line_string, etc)
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- Minimal dependencies for usage of enclosing `geometry` type (`mapbox::variant`)
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- Easily [adaptable to `boost::geometry`](http://www.boost.org/doc/libs/1_56_0/libs/geometry/doc/html/geometry/examples/example__adapting_a_legacy_geometry_object_model.html)
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### Usage
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Using a single type directly (requires no external dependencies):
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```cpp
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#include <mapbox/geometry/point.hpp>
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#include <iostream>
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using mapbox::geometry::point;
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int main() {
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point<double> pt(1.0,0.0);
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std::clog << "x: " << pt.x << " y: " << pt.y << "\n";
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}
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```
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Creating a geometry collection (depends on https://github.com/mapbox/variant):
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```cpp
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#include <mapbox/geometry/geometry.hpp>
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#include <mapbox/variant.hpp>
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#include <iostream>
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using mapbox::geometry::geometry_collection;
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using mapbox::geometry::geometry;
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using mapbox::geometry::point;
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using point_type = point<double>;
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struct printer
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{
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printer() {}
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void operator()(point_type const& pt) const
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{
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std::clog << "x: " << pt.x << " y: " << pt.y << "\n";
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}
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template <typename T>
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void operator()(T const& g) const
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{
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std::clog << "encountered non-point geometry\n";
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}
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};
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int main() {
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geometry_collection<double> gc;
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gc.emplace_back(point_type(1.0,0.0));
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geometry<double> const& geom = gc.at(0);
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printer visitor;
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mapbox::util::apply_visitor(visitor,geom);
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}
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```
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