Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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within (with strategy)

Checks if the first geometry is completely inside the second geometry using the specified strategy.

Description

The free function within checks if the first geometry is completely inside the second geometry, using the specified strategy. Reasons to specify a strategy include: use another coordinate system for calculations; construct the strategy beforehand (e.g. with the radius of the Earth); select a strategy when there are more than one available for a calculation.

Synopsis

template<typename Geometry1, typename Geometry2, typename Strategy>
bool within(Geometry1 const & geometry1, Geometry2 const & geometry2, Strategy const & strategy)

Parameters

Type

Concept

Name

Description

Geometry1 const &

Any type fulfilling a Geometry Concept

geometry1

A model of the specified concept geometry which might be within the second geometry

Geometry2 const &

Any type fulfilling a Geometry Concept

geometry2

A model of the specified concept which might contain the first geometry

Strategy const &

strategy

strategy to be used

Returns

true if geometry1 is completely contained within geometry2, else false

Header

Either

#include <boost/geometry/geometry.hpp>

Or

#include <boost/geometry/algorithms/within.hpp>

Supported geometries

Box

Ring

Polygon

MultiPolygon

Point

ok

ok

ok

ok

Notes

If a point is located exactly on the border of a geometry, the result depends on the strategy. The default strategy (Winding (coordinate system agnostic)) returns false in that case.

If a polygon has a reverse oriented (e.g. counterclockwise for a clockwise typed polygon), the result also depends on the strategy. The default strategy returns still true if a point is completely within the reversed polygon. There is a specific strategy which returns false in this case.

Complexity

Linear

Available Strategies
Example

[within_strategy] [within_strategy_output]


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