The class Alpha_status<NT> is a small data strructure to store the critical alpha values of faces of an alpha shape. Each face has three critical alpha values, called alpha_min, alpha_mid and alpha_max in increasing order. The face will be exterior for any < alpha_min, singular for alpha_min < alpha_mid, regular for alpha_mid < alpha_max and interior for alpha_max alpha. The value alpha_min is undefined for faces which are not Gabriel faces and therefore do not appear in the alpha complex without any of their including face. The value alpha_max is undefined for convex hull faces which can never be interior, The data structure also includes two boolean to mark if the face is a Gabriel face or a convex hull face.

The class Alpha_status<NT> is paremetrized by a number type NT.

#include <CGAL/Alpha_shape_cell_base_3.h>


Alpha_status<NT> a;
default constructor.


void a.set_is_Gabriel ( bool yesorno)
sets Gabriel marker;
void a.set_is_on_chull ( bool yesorno)
sets convex hull marker;
void a.set_alpha_min ( NT alpha)
sets alpha_min.
void a.set_alpha_mid ( NT alpha)
sets alpha_mid.
void a.set_alpha_max ( NT alpha)
sets alpha_max.

Access Functions

bool a.is_Gabriel () Returns true for Gabriel faces;
bool a.is_on_chull () Returns true forconvex hull faces;
NT a.alpha_min () Returns the alpha_min
Precondition: is_Gabriel() returns false;
NT a.alpha_mid () Returns the alpha_mid;
NT a.alpha_max () Returns alpha_max.
Precondition: is_on_chull() returns false.

See Also