The demos use Geomview
[see the chapter Geomview in the cgal manual - support library:
Geomview 1.8.1 is required.  The geomview command must be in the user's $PATH,
otherwise the program will not be able to execute.]

------- demo -------------------------------------------------
Construction of a Delaunay triangulation.

Needs an input file "data/points" containing points (given by x y z)

Draws the triangulation (vertices and edges) in geomview

Locates a point a shows the cell containing it

Draws the triangulation (edges and cells) in geomview,
then the user can move one of the two displayed versions
of the triangulation.
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------- demo_color -------------------------------------------
Constructs a Delaunay triangulation with a special Vertex base class
containing a color (white by default).

Sets the color of degree 6 vertices to red.

Displays the triangulation where each vertex has its own color.
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------- demo_voronoi ------------------------------------------
Constructs a Delaunay triangulation for points on a grid.

Displays the Voronoi edges of the set of points
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------- demo_remove ------------------------------------------
Constructs a Delaunay triangulation for points on a grid.

Then removes all the vertices in random order
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