DGtal  1.4.beta
exampleLatticeBallDelaunay2D.cpp
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1
53 #include "DGtal/base/Common.h"
55 #include "DGtal/geometry/tools/QuickHull.h"
57 #include "DGtal/shapes/SurfaceMesh.h"
58 #include "DGtal/io/writers/SurfaceMeshWriter.h"
59
60 using namespace DGtal::Z2i;
61 int main( int argc, char* argv[] )
62 {
63  int nb = argc > 1 ? atoi( argv[ 1 ] ) : 100; // nb points
64  double dR = argc > 2 ? atof( argv[ 2 ] ) : 10.0; // radius of ball
65  // (0) typedefs
67  typedef DGtal::DelaunayIntegralKernel< 2 > Kernel2D;
68  typedef DGtal::QuickHull< Kernel2D > Delaunay2D;
70  // (1) create range of random points in ball
71  std::vector< Point > V;
72  const double R2 = dR * dR;
73  const int R = (int) ceil( dR );
74  for ( int i = 0; i < nb; ) {
75  Point p( rand() % (2*R+1) - R, rand() % (2*R+1) - R, rand() % (2*R+1) - R );
76  if ( p.squaredNorm() < R2 ) { V.push_back( p ); i++; }
77  }
78  // (2) compute convex hull
80  Delaunay2D hull;
81  hull.setInput( V );
82  hull.computeConvexHull();
83  std::cout << "#points=" << hull.nbPoints()
84  << " #vertices=" << hull.nbVertices()
85  << " #facets=" << hull.nbFacets() << std::endl;
88  double total_time = 0;
89  std::for_each( hull.timings.cbegin(), hull.timings.cend(),
90  [&total_time] ( double t ) { total_time += t; } );
91  std::cout << "purge duplicates= " << round(hull.timings[ 0 ]) << " ms." << std::endl;
92  std::cout << "init simplex = " << round(hull.timings[ 1 ]) << " ms." << std::endl;
93  std::cout << "quickhull core = " << round(hull.timings[ 2 ]) << " ms." << std::endl;
94  std::cout << "compute vertices= " << round(hull.timings[ 3 ]) << " ms." << std::endl;
95  std::cout << "total time = " << round(total_time) << " ms." << std::endl;
97  // (3) build mesh
99  std::vector< RealPoint > positions;
100  hull.getVertexPositions( positions );
101  std::vector< std::vector< std::size_t > > facets;
102  hull.getFacetVertices( facets );
103  // Finite facets precede infinite facets => keep only finite facets
104  facets.resize( hull.nbFiniteFacets() );
105  // To viusalize the result, we build a surface mesh in R3 lying in
106  // the plane z=0 and composed of the Delaunay cells.
107  typedef DGtal::SpaceND< 3, int > Z3;
108  std::vector< Z3::RealPoint > positions3d;
109  for ( auto p : positions )
110  positions3d.push_back( Z3::RealPoint( p[ 0 ], p[ 1 ], 0.0 ) );
112  SMesh mesh( positions3d.cbegin(), positions3d.cend(),
113  facets.cbegin(), facets.cend() );
115  // (4) output result as OBJ file
117  std::ofstream out( "delaunay.obj" );
119  out.close();
121  return 0;
122 }
123
int main(int argc, char *argv[])
SurfaceMesh< RealPoint, RealVector > SMesh
Z2i this namespace gathers the standard of types for 2D imagery.
Aim: a geometric kernel to compute the Delaunay triangulation of digital points with integer-only ari...
Aim: Implements the quickhull algorithm by Barber et al. , a famous arbitrary dimensional convex hull...
Definition: QuickHull.h:140
static bool writeOBJ(std::ostream &output, const SurfaceMesh &smesh)
Aim: Represents an embedded mesh as faces and a list of vertices. Vertices may be shared among faces ...
Definition: SurfaceMesh.h:92
PointVector< 3, double > RealPoint