TGraphDelaunay2D.cxx

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// @(#)root/hist:$Id: TGraphDelaunay2D.cxx,v 1.00
// Author: Olivier Couet, Luke Jones (Royal Holloway, University of London)

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
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 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
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#include "TMath.h"
#include "TGraph2D.h"
#include "TGraphDelaunay2D.h"

//#include <thread>

ClassImp(TGraphDelaunay2D)


//______________________________________________________________________________
//
// TGraphDelaunay2D generates a Delaunay triangulation of a TGraph2D. This
// triangulation code derives from an implementation done by Luke Jones
// (Royal Holloway, University of London) in April 2002 in the PAW context.
//
// This software cannot be guaranteed to work under all circumstances. They
// were originally written to work with a few hundred points in an XY space
// with similar X and Y ranges.
//
// Definition of Delaunay triangulation (After B. Delaunay):
// For a set S of points in the Euclidean plane, the unique triangulation DT(S)
// of S such that no point in S is inside the circumcircle of any triangle in
// DT(S). DT(S) is the dual of the Voronoi diagram of S. If n is the number of
// points in S, the Voronoi diagram of S is the partitioning of the plane
// containing S points into n convex polygons such that each polygon contains
// exactly one point and every point in a given polygon is closer to its
// central point than to any other. A Voronoi diagram is sometimes also known
// as a Dirichlet tessellation.
//Begin_Html
/*
<img src="gif/dtvd.gif">
<br>
<a href="http://www.cs.cornell.edu/Info/People/chew/Delaunay.html">This applet</a>
gives a nice practical view of Delaunay triangulation and Voronoi diagram.
*/
//End_Html




/// TGraphDelaunay2D normal constructor
TGraphDelaunay2D::TGraphDelaunay2D(TGraph2D *g ) :
   TNamed("TGraphDelaunay2D","TGraphDelaunay2D"),
   fGraph2D(g), 
   fDelaunay((g) ? g->GetN() : 0, (g) ? g->GetX() : nullptr, (g) ? g->GetY() : nullptr, (g) ? g->GetZ() : nullptr ,
             (g) ? g->GetXmin() : 0, (g) ? g->GetXmax() : 0,
             (g) ? g->GetYmin() : 0, (g) ? g->GetYmax() : 0 ) 
   
{}