DGtal 1.3.0
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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
60using namespace DGtal::Z2i;
61int 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
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
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
int main()
Definition: testBits.cpp:56