Logo ROOT  
Reference Guide
 
Loading...
Searching...
No Matches
TGraphDelaunay2D.cxx
Go to the documentation of this file.
1// @(#)root/hist:$Id: TGraphDelaunay2D.cxx,v 1.00
2// Author: Olivier Couet, Luke Jones (Royal Holloway, University of London)
3
4/*************************************************************************
5 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *
6 * All rights reserved. *
7 * *
8 * For the licensing terms see $ROOTSYS/LICENSE. *
9 * For the list of contributors see $ROOTSYS/README/CREDITS. *
10 *************************************************************************/
11
12#include "TGraph2D.h"
13#include "TGraphDelaunay2D.h"
14
16
17
18/** \class TGraphDelaunay2D
19 \ingroup Graphs
20TGraphDelaunay2D generates a Delaunay triangulation of a TGraph2D.
21The algorithm used for finding the triangles is based on [CDT](https://github.com/artem-ogre/CDT),
22a C++ library for generating constraint or conforming Delaunay triangulations.
23
24The ROOT::Math::Delaunay2D class provides a wrapper for using
25the **CDT** library.
26
27This implementation provides large improvements in terms of computational performances
28compared to the legacy one available in TGraphDelaunay, and it is by default
29used in TGraph2D. The old, legacy implementation can be still used when calling
30`TGraph2D::GetHistogram` and `TGraph2D::Draw` with the `old` option.
31
32Definition of Delaunay triangulation (After B. Delaunay):
33For a set S of points in the Euclidean plane, the unique triangulation DT(S)
34of S such that no point in S is inside the circumcircle of any triangle in
35DT(S). DT(S) is the dual of the Voronoi diagram of S. If n is the number of
36points in S, the Voronoi diagram of S is the partitioning of the plane
37containing S points into n convex polygons such that each polygon contains
38exactly one point and every point in a given polygon is closer to its
39central point than to any other. A Voronoi diagram is sometimes also known
40as a Dirichlet tessellation.
41
42\image html tgraph2d_delaunay.png
43
44[This applet](http://www.cs.cornell.edu/Info/People/chew/Delaunay.html)
45gives a nice practical view of Delaunay triangulation and Voronoi diagram.
46*/
47
48/// TGraphDelaunay2D normal constructor
50 TNamed("TGraphDelaunay2D","TGraphDelaunay2D"),
51 fGraph2D(g),
52 fDelaunay((g) ? g->GetN() : 0, (g) ? g->GetX() : nullptr, (g) ? g->GetY() : nullptr, (g) ? g->GetZ() : nullptr ,
53 (g) ? g->GetXmin() : 0, (g) ? g->GetXmax() : 0,
54 (g) ? g->GetYmin() : 0, (g) ? g->GetYmax() : 0 )
55
56{}
57
#define g(i)
Definition RSha256.hxx:105
#define ClassImp(name)
Definition Rtypes.h:377
Graphics object made of three arrays X, Y and Z with the same number of points each.
Definition TGraph2D.h:41
TGraphDelaunay2D generates a Delaunay triangulation of a TGraph2D.
TGraphDelaunay2D(const TGraphDelaunay2D &)=delete
The TNamed class is the base class for all named ROOT classes.
Definition TNamed.h:29