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Reference Guide
radialgradients.C
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1/// \file
2/// \ingroup tutorial_gl
3/// This tutorial demonstrates how to use radial gradients,
4/// custom colors, transparency.
5/// Requires OpenGL: either set OpenGL.CanvasPreferGL to 1
6/// in the $ROOTSYS/etc/system.rootrc,
7/// or use `gStyle->SetCanvasPreferGL(kTRUE)`.
8///
9/// \macro_image(nobatch)
10/// \macro_code
11///
12/// \author Timur Pocheptsov
13
14//Includes for ACLiC:
15#include <cassert>
16#include <cstdlib>
17
18#include "TColorGradient.h"
19#include "TEllipse.h"
20#include "TRandom.h"
21#include "TCanvas.h"
22#include "TStyle.h"
23
24#include "TError.h"
25
26//Aux. functions.
27#include "customcolorgl.h"
28
29namespace {
30
31//Just some colors (rgba) to build our
32//fancy gradients from.
33const Double_t basicColors[][4] =
34{
35{1., 0., 0., 1.},
36{1., 0.3, 0., 1.},
37{0., 0., 1., 1.},
38{1., 1., 0., 1.},
39{1., 0., 1., 1.},
40{0., 1., 1., 1.},
41{0., 1., 0., 1.},
42{0., 0.5, 0., 1.},
43//transparent colors:
44{1., 0., 0., 0.5},
45{1., 0.3, 0., 0.5},
46{0., 0., 1., 0.5},
47{1., 1., 0., 0.5},
48{1., 0., 1., 0.5},
49{0., 1., 1., 0.5},
50{0., 1., 0., 0.5},
51{0., 0.5, 0., 0.5},
52//and even more transparent:
53{1., 0., 0., 0.2},
54{1., 0.3, 0., 0.2},
55{0., 0., 1., 0.2},
56{1., 1., 0., 0.2},
57{1., 0., 1., 0.2},
58{0., 1., 1., 0.2},
59{0., 1., 0., 0.2},
60{0., 0.5, 0., 0.2}
61};
62
63const unsigned nBasicColors = sizeof basicColors / sizeof basicColors[0];
64
65//______________________________________________________________________
66Color_t CreateRandomGradientFill()
67{
68 const Double_t * const fromRGBA = basicColors[(std::rand() % (nBasicColors / 2))];
69 //With odd number of colors the last one is never selected :)
70 const Double_t * const toRGBA = basicColors[nBasicColors / 2 + (std::rand() % (nBasicColors / 2))];
71
72 const Double_t locations[] = {0., 1.};
73 const Double_t rgbas[] = {fromRGBA[0], fromRGBA[1], fromRGBA[2], fromRGBA[3],
74 toRGBA[0], toRGBA[1], toRGBA[2], toRGBA[3]};
75
76 Color_t idx[1] = {};
78 return -1;
79
80 TRadialGradient * const grad = new TRadialGradient(idx[0], 2, locations, rgbas);
81 //
82 grad->SetRadialGradient(TColorGradient::Point(0.5, 0.5), 0.5);
83
84 return idx[0];
85}
86
87//______________________________________________________________________
88bool add_ellipse(const Double_t xC, const Double_t yC, const Double_t r)
89{
90 assert(gPad != nullptr && "add_ellipse, no pad to add ellipse");
91
92 const Color_t newColor = CreateRandomGradientFill();
93 if (newColor == -1) {
94 ::Error("add_ellipse", "failed to find a new color index for a gradient fill");
95 return false;
96 }
97
98 TEllipse * const newEllipse = new TEllipse(xC, yC, r, r);
99 newEllipse->SetFillColor(newColor);
100 newEllipse->Draw();
101
102 return true;
103}
104
105}
106
107//______________________________________________________________________
108void radialgradients()
109{
110 gRandom->SetSeed(4357);//;)
111
113
114 TCanvas * const cnv = new TCanvas("radial gradients", "radial gradients", 800, 800);
115 if (!cnv->UseGL()) {
116 ::Error("radialgradients", "this demo OpenGL");
117 delete cnv;
118 return;
119 }
120
121 for (unsigned i = 0; i < 100; ++i)
122 if (!add_ellipse(gRandom->Rndm(), gRandom->Rndm(), 0.5 * gRandom->Rndm()))
123 break;
124
125 cnv->Modified();
126 cnv->Update();
127}
short Color_t
Definition: RtypesCore.h:92
double Double_t
Definition: RtypesCore.h:59
const Bool_t kTRUE
Definition: RtypesCore.h:100
void Error(const char *location, const char *msgfmt,...)
Use this function in case an error occurred.
Definition: TError.cxx:187
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t r
R__EXTERN TRandom * gRandom
Definition: TRandom.h:62
R__EXTERN TStyle * gStyle
Definition: TStyle.h:414
#define gPad
Definition: TVirtualPad.h:288
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition: TAttFill.h:37
The Canvas class.
Definition: TCanvas.h:23
void Update() override
Update canvas pad buffers.
Definition: TCanvas.cxx:2492
Bool_t UseGL() const
Definition: TCanvas.h:223
Draw Ellipses.
Definition: TEllipse.h:23
void Draw(Option_t *option="") override
Draw this ellipse with its current attributes.
Definition: TEllipse.cxx:168
void Modified(Bool_t flag=1) override
Definition: TPad.h:414
Define a radial color gradient.
void SetRadialGradient(const Point &center, Double_t radius)
Set radial gradient.
virtual void SetSeed(ULong_t seed=0)
Set the random generator seed.
Definition: TRandom.cxx:608
Double_t Rndm() override
Machine independent random number generator.
Definition: TRandom.cxx:552
void SetCanvasPreferGL(Bool_t prefer=kTRUE)
Definition: TStyle.h:326
unsigned FindFreeCustomColorIndices(T(&indices)[N])
Definition: customcolorgl.h:40