CGAL::Alpha_status<NT>

Definition

The class Alpha_status<NT> is a small data structure 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 α< alpha_min, singular for alpha_min α< alpha_mid, regular for alpha_mid α< 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 parameterized by a number type NT.

#include <CGAL/Alpha_shape_cell_base_3.h>

Creation

Alpha_status<NT> a;
default constructor.

Modifiers

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

See Also

AlphaShapeCellBase_3
AlphaShapeVertexBase_3