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mandelbrot.C
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1/// \file
2/// \ingroup tutorial_graphics
3/// \notebook -js
4/// Using TExec to handle keyboard events and TComplex to draw the Mandelbrot set.
5///
6/// Pressing the keys 'z' and 'u' will zoom and unzoom the picture
7/// near the mouse location, 'r' will reset to the default view.
8///
9/// Try it (in compiled mode!) with: `root mandelbrot.C+`
10///
11/// \macro_image (tcanvas_js)
12///
13/// ### Details
14///
15/// when a mouse event occurs the myexec() function is called (by
16/// using AddExec). Depending on the pressed key, the mygenerate()
17/// function is called, with the proper arguments. Note the
18/// last_x and last_y variables that are used in myexec() to store
19/// the last pointer coordinates (px is not a pointer position in
20/// kKeyPress events).
21///
22/// \macro_code
23///
24/// \author Luigi Bardelli <bardelli@fi.infn.it>
25
26#include <TStyle.h>
27#include <TROOT.h>
28#include <TH2.h>
29#include <TComplex.h>
30#include <TVirtualPad.h>
31#include <TCanvas.h>
32
33TH2F *last_histo=NULL;
34
35void mygenerate(double factor, double cen_x, double cen_y)
36{
37 printf("Regenerating...\n");
38 // resize histo:
39 if(factor>0)
40 {
41 double dx=last_histo->GetXaxis()->GetXmax()-last_histo->GetXaxis()->GetXmin();
42 double dy=last_histo->GetYaxis()->GetXmax()-last_histo->GetYaxis()->GetXmin();
43 last_histo->SetBins(
44 last_histo->GetNbinsX(),
45 cen_x-factor*dx/2,
46 cen_x+factor*dx/2,
47 last_histo->GetNbinsY(),
48 cen_y-factor*dy/2,
49 cen_y+factor*dy/2
50 );
51 last_histo->Reset();
52 }
53 else
54 {
55 if(last_histo!=NULL) delete last_histo;
56 // allocate first view...
57 last_histo= new TH2F("h2",
58 "Mandelbrot [move mouse and press z to zoom, u to unzoom, r to reset]",
59 200,-2,2,200,-2,2);
60 last_histo->SetStats(0);
61 }
62 const int max_iter=50;
63 for(int bx=1;bx<=last_histo->GetNbinsX();bx++)
64 for(int by=1;by<=last_histo->GetNbinsY();by++)
65 {
66 double x=last_histo->GetXaxis()->GetBinCenter(bx);
67 double y=last_histo->GetYaxis()->GetBinCenter(by);
68 TComplex point( x,y);
69 TComplex z=point;
70 int iter=0;
71 while (z.Rho()<2){
72 z=z*z+point;
73 last_histo->Fill(x,y);
74 iter++;
75 if(iter>max_iter) break;
76 }
77 }
78 last_histo->SetContour(99);
79 last_histo->Draw("colz");
80 gPad->Modified();
81 gPad->Update();
82 printf("Done.\n");
83}
84
85void myexec()
86{
87 // get event information
88 int event = gPad->GetEvent();
89 int px = gPad->GetEventX();
90 int py = gPad->GetEventY();
91
92 // some magic to get the coordinates...
93 double xd = gPad->AbsPixeltoX(px);
94 double yd = gPad->AbsPixeltoY(py);
95 float x = gPad->PadtoX(xd);
96 float y = gPad->PadtoY(yd);
97
98 static float last_x;
99 static float last_y;
100
101 if(event!=kKeyPress)
102 {
103 last_x=x;
104 last_y=y;
105 return;
106 }
107
108 const double Z=2.;
109 switch(px){
110 case 'z': // ZOOM
111 mygenerate(1./Z, last_x, last_y);
112 break;
113 case 'u': // UNZOOM
114 mygenerate(Z , last_x, last_y);
115 break;
116 case 'r': // RESET
117 mygenerate(-1 , last_x, last_y);
118 break;
119 };
120}
121
122void mandelbrot()
123{
124 // cosmetics...
127 new TCanvas("canvas","View Mandelbrot set");
128 // this generates and draws the first view...
129 mygenerate(-1,0,0);
130
131 // add exec
132 gPad->AddExec("myexec","myexec()");
133}
@ kKeyPress
Definition: Buttons.h:20
const Bool_t kTRUE
Definition: RtypesCore.h:100
R__EXTERN TStyle * gStyle
Definition: TStyle.h:412
#define gPad
Definition: TVirtualPad.h:287
virtual Double_t GetBinCenter(Int_t bin) const
Return center of bin.
Definition: TAxis.cxx:478
Double_t GetXmax() const
Definition: TAxis.h:134
Double_t GetXmin() const
Definition: TAxis.h:133
The Canvas class.
Definition: TCanvas.h:23
Double_t Rho() const
Definition: TComplex.h:46
virtual Int_t GetNbinsY() const
Definition: TH1.h:297
TAxis * GetXaxis()
Get the behaviour adopted by the object about the statoverflows. See EStatOverflows for more informat...
Definition: TH1.h:320
virtual Int_t GetNbinsX() const
Definition: TH1.h:296
TAxis * GetYaxis()
Definition: TH1.h:321
virtual void SetContour(Int_t nlevels, const Double_t *levels=0)
Set the number and values of contour levels.
Definition: TH1.cxx:8326
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition: TH1.cxx:3074
virtual void SetBins(Int_t nx, Double_t xmin, Double_t xmax)
Redefine x axis parameters.
Definition: TH1.cxx:8610
virtual void SetStats(Bool_t stats=kTRUE)
Set statistics option on/off.
Definition: TH1.cxx:8833
2-D histogram with a float per channel (see TH1 documentation)}
Definition: TH2.h:251
virtual void Reset(Option_t *option="")
Reset this histogram: contents, errors, etc.
Definition: TH2.cxx:3670
Int_t Fill(Double_t)
Invalid Fill method.
Definition: TH2.cxx:358
void SetPadGridX(Bool_t gridx)
Definition: TStyle.h:345
void SetPadGridY(Bool_t gridy)
Definition: TStyle.h:346
Double_t y[n]
Definition: legend1.C:17
Double_t x[n]
Definition: legend1.C:17