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| <title>Boost Polygon Library: Coordinate Concept</title> |
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| <h3 class="navbar">Contents</h3> |
| <ul> |
| <li><a href="index.htm">Boost.Polygon Main Page</a></li> |
| <li><a href="gtl_design_overview.htm">Design Overview</a></li> |
| <li><a href="gtl_isotropy.htm">Isotropy</a></li> |
| <li>Coordinate Concept</li> |
| <li><a href="gtl_interval_concept.htm">Interval Concept</a></li> |
| <li><a href="gtl_point_concept.htm">Point Concept</a></li> |
| <li><a href="gtl_rectangle_concept.htm">Rectangle Concept</a></li> |
| <li><a href="gtl_polygon_90_concept.htm">Polygon 90 Concept</a></li> |
| <li><a href="gtl_polygon_90_with_holes_concept.htm">Polygon 90 With Holes Concept</a></li> |
| <li><a href="gtl_polygon_45_concept.htm">Polygon 45 Concept</a></li> |
| <li><a href="gtl_polygon_45_with_holes_concept.htm">Polygon 45 With Holes Concept</a></li> |
| <li><a href="gtl_polygon_concept.htm">Polygon Concept</a></li> |
| <li><a href="gtl_polygon_with_holes_concept.htm">Polygon With Holes Concept</a></li> |
| <li><a href="gtl_polygon_90_set_concept.htm">Polygon 90 Set Concept</a></li> |
| <li><a href="gtl_polygon_45_set_concept.htm">Polygon 45 Set Concept</a></li> |
| <li><a href="gtl_polygon_set_concept.htm">Polygon Set Concept</a></li> |
| <li><a href="gtl_connectivity_extraction_90.htm">Connectivity Extraction 90</a></li> |
| <li><a href="gtl_connectivity_extraction_45.htm">Connectivity Extraction 45</a></li> |
| <li><a href="gtl_connectivity_extraction.htm">Connectivity Extraction</a></li> |
| <li><a href="gtl_property_merge_90.htm">Property Merge 90</a></li> |
| <li><a href="gtl_property_merge_45.htm">Property Merge 45</a></li> |
| <li><a href="gtl_property_merge.htm">Property Merge</a></li> |
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| <h3 class="navbar">Other Resources</h3> |
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| <li><a href="GTL_boostcon2009.pdf">GTL Boostcon 2009 Paper</a></li> |
| <li><a href="GTL_boostcon_draft03.pdf">GTL Boostcon 2009 |
| Presentation</a></li> |
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| <li><a href="gtl_tutorial.htm">Layout Versus Schematic Tutorial</a></li> |
| <li><a href="gtl_minkowski_tutorial.htm">Minkowski Sum Tutorial</a></li> |
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| <p> |
| </p><h1>Coordinate Concept</h1> |
| |
| <p> |
| The coordinate concept tag is <font face="Courier New"> |
| coordinate_concept</font><p> |
| To register a user defined type as a model of coordinate concept, specialize the |
| geometry concept meta-function for that type. In the example below |
| CCoordinate is registered as a model of coordinate concept.<p> |
| <font face="Courier New">template <><br> |
| struct geometry_concept<CCoordinate> { typedef coordinate_concept type; };</font><p> |
| The coordinate type is expected to be integral and built-in numerical data types |
| such as float and int already have concept type traits specializations in the |
| library. In the coordinate traits are type definitions for related types |
| are provided to allow the library to choose the best type to cast to under |
| various circumstances. The definition of coordinate_traits and its |
| specialization for int are shown below.<p> |
| <font face="Courier New">template <typename T><br> |
| struct coordinate_traits {};<br> |
| <br> |
| template <><br> |
| struct coordinate_traits<int> {<br> |
| typedef int coordinate_type;<br> |
| typedef long double area_type;<br> |
| typedef long long manhattan_area_type;<br> |
| typedef unsigned long long unsigned_area_type;<br> |
| typedef long long coordinate_difference;<br> |
| typedef long double coordinate_distance;<br> |
| };</font><p> |
| By making use of the coordinate traits of int the library is able to avoid |
| overflow and handle the normal issues encountered when programming integer |
| geometry. For the out of the ordinary issues there is a special |
| meta-function that provides the library with a numerical type suitable for exact |
| numerical calculations. It defaults to the highest precision data type |
| available in most compilers, long double, but can be overridden by specializing |
| for a particular coordinate type. Use of gmp multi-precision rational or |
| similar data type is recommended for numerically robust calculations in the |
| general polygon algorithms.<p> |
| <font face="Courier New">template <typename T><br> |
| struct high_precision_type {<br> |
| typedef long double type;<br> |
| };</font><p> |
| There is only one generic function on coordinate concepts, Euclidean distance.<p> |
| <font face="Courier New">template <typename coordinate_type_1, typename |
| coordinate_type_2><br> |
| coordinate_difference euclidean_distance(coordinate_type_1, coordinate_type_2)</font><p> |
| This function returns the absolution value of the difference between the two |
| coordinates.<p> |
| Note: older versions of the stl define a fully generic distance(T, T) function |
| for computing the difference between two iterators. We were forced to name |
| our distance function euclidean_distance to avoid name collision.<p> |
| The |
| <a href="http://www.mentor.com/products/esl/high_level_synthesis/ac_datatypes"> |
| Algorithmic C</a> ac_int<128> is an example of a user defined coordinate data |
| type that satisfies the coordinate concept. In general a data type should |
| define std::numeric_limits and be integer-like. Floating point coordinate |
| types are not supported by all the algorithms and generally not suitable for use |
| with the library at present.<tr> |
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| <th class="docinfo-name">Copyright:</th> |
| <td>Copyright © Intel Corporation 2008-2010.</td> |
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| <td class="field-body">Distributed under the Boost Software License, |
| Version 1.0. (See accompanying file <tt class="literal"> |
| <span class="pre">LICENSE_1_0.txt</span></tt> or copy at |
| <a class="reference" target="_top" href="http://www.boost.org/LICENSE_1_0.txt"> |
| http://www.boost.org/LICENSE_1_0.txt</a>)</td> |
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