colored super ellipse [fltk]

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 12 Exercise 13
Using GUI library called FLTK (Fast Light Tool Kit, “full tick”).

Output: n = 4

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PP
// Chapter 12 Exercise 13

#define _USE_MATH_DEFINES
#include "Simple_window.h"
#include "Graph.h"
#include <cmath>
using namespace Graph_lib;

int main()
try
{
Point tl(100, 100);
Simple_window win(tl, 600, 400, "Regular Polygons");

Point center(win.x_max() / 2, win.y_max() / 2);
Graph_lib::Open_polyline supEllipse0;
supEllipse0.set_color(Color::red);
Graph_lib::Open_polyline supEllipse1;
supEllipse1.set_color(Color::green);
Graph_lib::Open_polyline supEllipse2;
supEllipse2.set_color(Color::blue);
Graph_lib::Open_polyline supEllipse3;
supEllipse3.set_color(Color::black);

double a = 100;
double y;
double b = 100;
double n; // 1/2; 3/2; 2; 4;
n = 4.0;

for (int x = -100; x < 0; x++) {
y = b * pow(1 – pow(abs(x / a), n), 1 / n);
supEllipse0.add(Point(x + center.x, y + center.y));
}
for (int x = 0; x < 101; x++) {
y = b * pow(1 – pow(abs(x / a), n), 1 / n);
supEllipse1.add(Point(x + center.x, y + center.y));
}

for (int x = 100; x > 0; x–) {
y = b * pow(1 – pow(abs(x / a), n), 1 / n);
y = -y;
supEllipse2.add(Point(x + center.x, y + center.y));
}

for (int x = 0; x > -101; x–) {
y = b * pow(1 – pow(abs(x / a), n), 1 / n);
y = -y;
supEllipse3.add(Point(x + center.x, y + center.y));
}

win.attach(supEllipse0);
win.attach(supEllipse1);
win.attach(supEllipse2);
win.attach(supEllipse3);
win.wait_for_button();
}
catch (exception& e) {
cout << e.what() << endl;
return 1;
}
catch (…) {
cout << "Exiting" << endl;
return 2;
}
[/code]

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