(C++) BoostGeometryExample3

 

 

Boost.Geometry example 3: IsConvex: determine if a 2D polygon is convex or concave is a Boost.Geometry example.

 

IsConvex is maintained in CppGeometry. See CppGeometry for the heavily used, debugged and tested version of IsConvex

Technical facts

 

Application type(s)

• Desktop application

Operating system(s) or programming environment(s)

• Lubuntu 15.04 (vivid)

IDE(s):

• Qt Creator 3.1.1

Project type:

• GUI application

C++ standard:

• C++11

Compiler(s):

• G++ 4.9.2

Libraries used:

• Qt: version 5.4.1 (32 bit)
• STL: GNU ISO C++ Library, version 4.9.2

 

 

 

 

 

Qt project file: ./CppBoostGeometryExample3/CppBoostGeometryExample3.pro

 

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exists(../../ConsoleApplication.pri) {   include(../../ConsoleApplication.pri) } !exists(../../ConsoleApplication.pri) {   QT += core   QT += gui   greaterThan(QT_MAJOR_VERSION, 4): QT += widgets   CONFIG   += console   CONFIG   -= app_bundle   TEMPLATE = app   CONFIG(release, debug|release) {     DEFINES += NDEBUG NTRACE_BILDERBIKKEL   }   QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra -Weffc++   unix {     QMAKE_CXXFLAGS += -Werror   } } exists(../../Libraries/Boost.pri) {   include(../../Libraries/Boost.pri) } !exists(../../Libraries/Boost.pri) {   win32 {     INCLUDEPATH += \       ../../Libraries/boost_1_55_0   } } SOURCES += main.cpp

 

 

 

 

 

./CppBoostGeometryExample3/main.cpp

 

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#include <cassert> #include <iostream> #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-variable" #include <boost/geometry.hpp> #include <boost/geometry/geometries/point_xy.hpp> #pragma GCC diagnostic pop bool IsConvex(boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double>> polygon) {   boost::geometry::correct(polygon);   boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double>> hull;   boost::geometry::convex_hull(polygon, hull);   return boost::geometry::area(hull) == boost::geometry::area(polygon); } int main() {   typedef boost::geometry::model::d2::point_xy<double> Coordinat2D;   /* Polygons used:   0123456789012    0123456789012 0+------------   0+------------ 1|               1| 2| A---------B   2| A---------B 3| E        /    3|  \   D   / 4|  \      /     4|   \ / \ / 5|   D----C      5|    E   C   |                |      Convex           Concave   */   //Convex shape   {     const std::vector<Coordinat2D> points {       { 2.0, 2.0}, //A       {12.0, 2.0}, //B       { 9.0, 5.0}, //C       { 4.0, 5.0}, //D       { 2.0, 3.0}  //E     };     boost::geometry::model::polygon<Coordinat2D> polygon;     boost::geometry::append(polygon, points);     assert(IsConvex(polygon));   }   //Concave shape   {     const std::vector<Coordinat2D> points {       { 2.0, 2.0}, //A       {12.0, 2.0}, //B       { 9.0, 5.0}, //C       { 7.0, 3.0}, //D       { 5.0, 5.0}  //E     };     boost::geometry::model::polygon<Coordinat2D> polygon;     boost::geometry::append(polygon, points);     assert(!IsConvex(polygon));   } }