geometry/tools/determinant/exampleInHalfPlane.cpp

Example of geometric predicates.

See also

Implementation of geometric predicates

 
#include <iostream>
#include "DGtal/base/Common.h"
 
#include "DGtal/kernel/SpaceND.h"
#include "DGtal/kernel/domains/HyperRectDomain.h"
 
#include "DGtal/geometry/tools/determinant/Simple2x2DetComputer.h"
#include "DGtal/geometry/tools/determinant/SimpleIncremental2x2DetComputer.h"
#include "DGtal/geometry/tools/determinant/AvnaimEtAl2x2DetSignComputer.h"
#include "DGtal/geometry/tools/determinant/Filtered2x2DetComputer.h"
#include "DGtal/geometry/tools/determinant/InHalfPlaneBy2x2DetComputer.h"
#include "DGtal/geometry/tools/determinant/PredicateFromOrientationFunctor2.h"
#include "DGtal/geometry/tools/determinant/InHalfPlaneBySimple3x3Matrix.h"
 
using namespace std;
using namespace DGtal;
 
 
bool 
basicUsage()
{
  //domain definition
  typedef SpaceND< 2, DGtal::int16_t > DigitalSpace;
  typedef HyperRectDomain< DigitalSpace > Domain; 
  typedef Domain::Point Point; 
  Domain domain( Point(-32767,-32767), Point(32767,32767) ); 
 
  Point P, Q, R; 
  P = Point(0,0); 
  Q = Point(5,2); 
  R = Point(2,1); 
  //problem: are P, Q, R counter-clockwise oriented ?
 
  //orientation functor
  typedef InHalfPlaneBySimple3x3Matrix<Point, DGtal::int32_t> OrientationFunctor; 
  OrientationFunctor orientationFunctor;
 
  //geometric predicate
  PredicateFromOrientationFunctor2<OrientationFunctor> 
    pointPredicate( orientationFunctor ); 
 
  //initialization
  pointPredicate.init( P, Q ); 
  //which is equivalent to 
  //orientationFunctor.init( P, Q );
  //because the predicate stores a pointer to the functor
 
  bool isCCW; 
  //decision
  isCCW = pointPredicate( R ); 
  //which is equivalent to the following shortcut:
  //isCCW = pointPredicate( P, Q, R ); 
 
  return isCCW; 
}
 
void
advice()
{
  {
  //for coordinates of 30 (not zero) bits
  typedef PointVector<2, DGtal::int32_t> Point; 
  typedef InHalfPlaneBySimple3x3Matrix<Point, DGtal::int64_t> Functor; 
  Functor *a = new Functor();
  BOOST_VERIFY(a);
  delete a;
  }
 
  {
  //for coordinates of 52 (not zero) bits
  typedef PointVector<2, DGtal::int64_t> Point;  
  typedef AvnaimEtAl2x2DetSignComputer<double> DetComputer; 
  typedef Filtered2x2DetComputer<DetComputer> FDetComputer; 
  typedef InHalfPlaneBy2x2DetComputer<Point, FDetComputer> Functor; 
  Functor *a = new Functor();
  BOOST_VERIFY(a);
  delete a;
  //NB. using double as coordinate type is slightly faster than using DGtal::int64_t
  //typedef PointVector<2, double> Point;  
  }
 
  {
  //for coordinates of 62 (not zero) bits
  typedef PointVector<2, DGtal::int64_t> Point; 
  typedef AvnaimEtAl2x2DetSignComputer<DGtal::int64_t> DetComputer; 
  typedef InHalfPlaneBy2x2DetComputer<Point, DetComputer> Functor; 
  Functor *a= new Functor();
  BOOST_VERIFY( a);
  delete a;
  }
 
  {
  //for coordinates of 62 (not zero) bits
  //if long double is implemented as the 80-bit extended precision type
  typedef PointVector<2, DGtal::int64_t> Point;  
  typedef AvnaimEtAl2x2DetSignComputer<long double> DetComputer; 
  typedef Filtered2x2DetComputer<DetComputer> FDetComputer; 
  typedef InHalfPlaneBy2x2DetComputer<Point, FDetComputer> Functor; 
  Functor *a = new Functor();
  BOOST_VERIFY(a == a);
  delete a;
  }
 
#ifdef WITH_BIGINTEGER
  {
  //for arbitrary coordinates
  typedef PointVector<2, DGtal::BigInteger> Point; 
  typedef Simple2x2DetComputer<DGtal::BigInteger> DetComputer; 
  typedef InHalfPlaneBy2x2DetComputer<Point, DetComputer> Functor; 
  Functor *a= new Functor();
  BOOST_VERIFY( a);
  delete a;
  }
#endif
 
}
 
int main( int argc, char** argv )
{
  trace.beginBlock ( "Example exampleInHalfPlane" );
  trace.info() << "Args:";
  for ( int i = 0; i < argc; ++i )
    trace.info() << " " << argv[ i ];
  trace.info() << endl;
 
  basicUsage(); 
  advice(); 
 
  trace.endBlock();
  return 0;
}
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