CGAL users discussion list

[Helios <>]

Respected sir/mam,

I'm using CGAL with python to draw Voronoi diagram. I would like to compute the set of edges that surround a particular site when the voronoi diagram is restricted to a box.

```

import numpy as np

from CGAL import CGAL_Kernel

from CGAL.CGAL_Voronoi_diagram_2 import Voronoi_diagram_2

from CGAL.CGAL_Triangulation_2 import Delaunay_triangulation_2

sites = np.array([[-3, 2], [-5, -3], [2,5], [0,5], [0,0]], dtype=float)

print("sites = ", sites,end="\n\n")

sites_cgal = [CGAL_Kernel.Point_2(x, y) for x, y in sites]

dt = Delaunay_triangulation_2()

dt.insert(sites_cgal)

vd = Voronoi_diagram_2(dt)

for f in vd.faces():

    e = f.halfedge()

    d = f.dual()

    print('site = ', d.point())

    s = [e.source().point().x(),e.source().point().y()] if e.has_source() else [None,None]

    t = [e.target().point().x(),e.target().point().y()] if e.has_target() else [None,None]

    print("edge : source = ",s,", target = ", t)

    while True:

        e = e.next()

        sn = [e.source().point().x(),e.source().point().y()] if e.has_source() else [None,None]

        tn = [e.target().point().x(),e.target().point().y()] if e.has_target() else [None,None]

        if [s,t] == [sn,tn]:

            break

        else:

            print("edge : source = ", sn,", target = ", tn)

    

    print("\n")

```

I have written a program to compute the bounded edges around a particular site in anti-clockwise direction but I am unable to compute it in case of unbounded edges. In case of unbounded edges since souce or target is in infinity, to prevent the kernel from crashing I have printed them as `None`

I need to clip the unbounded edges that has source or target in infinity and then find the edges that it traverses along the bounding box for every site.

Or I would like to know if there is any other component other than source and target that is stored in the unbounded edge case that can be used to convert it into a ray or segment or something else.

Thank you 

Regards

Sawvranu Dey