\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - 3D Alpha Shapes

All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Groups Pages
Alpha_shapes_3/ex_periodic_alpha_shapes_3.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Periodic_3_Delaunay_triangulation_traits_3.h>
#include <CGAL/Periodic_3_Delaunay_triangulation_3.h>
#include <CGAL/Alpha_shape_3.h>
#include <CGAL/Random.h>
#include <CGAL/point_generators_3.h>
// Traits
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Periodic_3_Delaunay_triangulation_traits_3<K> PK;
// Vertex type
typedef CGAL::Periodic_3_triangulation_ds_vertex_base_3<> DsVb;
typedef CGAL::Triangulation_vertex_base_3<PK,DsVb> Vb;
typedef CGAL::Alpha_shape_vertex_base_3<PK,Vb> AsVb;
// Cell type
typedef CGAL::Periodic_3_triangulation_ds_cell_base_3<> DsCb;
typedef CGAL::Triangulation_cell_base_3<PK,DsCb> Cb;
typedef CGAL::Alpha_shape_cell_base_3<PK,Cb> AsCb;
typedef CGAL::Triangulation_data_structure_3<AsVb,AsCb> Tds;
typedef CGAL::Periodic_3_Delaunay_triangulation_3<PK,Tds> P3DT3;
typedef CGAL::Alpha_shape_3<P3DT3> Alpha_shape_3;
typedef PK::Point_3 Point;
int main()
{
typedef CGAL::Creator_uniform_3<double, Point> Creator;
CGAL::Random random(7);
CGAL::Random_points_in_cube_3<Point, Creator> in_cube(1, random);
std::vector<Point> pts;
// Generating 1000 random points
for (int i=0 ; i < 1000 ; i++) {
Point p = *in_cube++;
pts.push_back(p);
}
// Define the periodic cube
P3DT3 pdt(PK::Iso_cuboid_3(-1,-1,-1,1,1,1));
// Heuristic for inserting large point sets (if pts is reasonably large)
pdt.insert(pts.begin(), pts.end(), true);
// As pdt won't be modified anymore switch to 1-sheeted cover if possible
if (pdt.is_triangulation_in_1_sheet()) pdt.convert_to_1_sheeted_covering();
std::cout << "Periodic Delaunay computed." << std::endl;
// compute alpha shape
Alpha_shape_3 as(pdt);
std::cout << "Alpha shape computed in REGULARIZED mode by default."
<< std::endl;
// find optimal alpha values
Alpha_shape_3::NT alpha_solid = as.find_alpha_solid();
Alpha_shape_3::Alpha_iterator opt = as.find_optimal_alpha(1);
std::cout << "Smallest alpha value to get a solid through data points is "
<< alpha_solid << std::endl;
std::cout << "Optimal alpha value to get one connected component is "
<< *opt << std::endl;
as.set_alpha(*opt);
assert(as.number_of_solid_components() == 1);
return 0;
}