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<title>Point Concept</title>
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<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="geometry.reference.concepts.concept_point"></a><a class="link" href="concept_point.html" title="Point Concept">Point Concept</a>
</h4></div></div></div>
<h6>
<a name="geometry.reference.concepts.concept_point.h0"></a>
<span class="phrase"><a name="geometry.reference.concepts.concept_point.description"></a></span><a class="link" href="concept_point.html#geometry.reference.concepts.concept_point.description">Description</a>
</h6>
<p>
The Point Concept describes the requirements for a point type. All algorithms
in Boost.Geometry will check any geometry arguments against the concept
requirements.
</p>
<p>
A point is <span class="emphasis"><em>an entity that has a location in space or on a plane,
but has no extent</em></span> (<a href="http://en.wikipedia.org/wiki/Point_(geometry)" target="_top">wiki</a>).
The point is the most basic geometry of Boost.Geometry, most other geometries
consist of points. <span class="emphasis"><em>(Exceptions are box and segment, which might
consist of two points but that is not necessarily the case.)</em></span>
</p>
<h6>
<a name="geometry.reference.concepts.concept_point.h1"></a>
<span class="phrase"><a name="geometry.reference.concepts.concept_point.concept_definition"></a></span><a class="link" href="concept_point.html#geometry.reference.concepts.concept_point.concept_definition">Concept
Definition</a>
</h6>
<p>
The Point Concept is defined as following:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
there must be a specialization of <code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">tag</span></code>,
defining <code class="computeroutput"><span class="identifier">point_tag</span></code>
as type
</li>
<li class="listitem">
there must be a specialization of <code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">coordinate_type</span></code>,
defining the type of its coordinates
</li>
<li class="listitem">
there must be a specialization of <code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">coordinate_system</span></code>,
defining its coordinate system (cartesian, spherical, etc)
</li>
<li class="listitem">
there must be a specialization of <code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">dimension</span></code>,
defining its number of dimensions (2, 3, ...) (hint: derive it conveniently
from <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">int_</span><span class="special"><</span><span class="identifier">X</span><span class="special">></span></code>
for X Dimensional)
</li>
<li class="listitem">
there must be a specialization of <code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">access</span></code>,
per dimension, with two functions:
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<code class="computeroutput"><span class="identifier">get</span></code> to get a
coordinate value
</li>
<li class="listitem">
<code class="computeroutput"><span class="identifier">set</span></code> to set a
coordinate value (this one is not checked for ConstPoint)
</li>
</ul></div>
</li>
</ul></div>
<h6>
<a name="geometry.reference.concepts.concept_point.h2"></a>
<span class="phrase"><a name="geometry.reference.concepts.concept_point.available_models"></a></span><a class="link" href="concept_point.html#geometry.reference.concepts.concept_point.available_models">Available
Models</a>
</h6>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a class="link" href="../models/model_point.html" title="model::point">model::point</a>
</li>
<li class="listitem">
<a class="link" href="../models/model_d2_point_xy.html" title="model::d2::point_xy">model::d2::point_xy</a>
</li>
<li class="listitem">
a lat long point (currently in an extension)
</li>
<li class="listitem">
<a class="link" href="../adapted/c_array.html" title="C array">C array</a>
</li>
<li class="listitem">
<a class="link" href="../adapted/boost_array.html" title="Boost.Array">Boost.Array</a>
</li>
<li class="listitem">
<a class="link" href="../adapted/boost_fusion.html" title="Boost.Fusion">Boost.Fusion</a>
</li>
<li class="listitem">
<a class="link" href="../adapted/boost_polygon.html" title="Boost.Polygon">Boost.Polygon</a>
</li>
<li class="listitem">
<a class="link" href="../adapted/boost_tuple.html" title="Boost.Tuple">Boost.Tuple</a>
</li>
<li class="listitem">
other point types, adapted e.g. using one of the <a class="link" href="../adapted.html" title="Adapted models">registration
macro's</a>
</li>
</ul></div>
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Wulkiewicz, Oracle and/or its affiliates<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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