Programming and Graphics

8.2 Graphics events 275

To control the animation frequency, we use theglutTimerFunccallback.
The following code contained in the filebounce.ccanimates a bouncing disk:

#include <iostream>

#include <cmath>

#include <freeglut.h>

using namespace std;

void animate(int);

void disk();

void quit(unsigned char, int, int);

//--- Global variables:

int delay=10, N=64;

float Dtheta = 2*3.1415926/N;

float centerx = 0.0, centery = 0.0, radius = 0.1;

float Dx = 0.02, Dy=0.01;

int win;

//---------- main

int main(int argc, char **argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUTDEPTH|GLUTDOUBLE | GLUTRGBA);

glutInitWindowPosition(500,100);

glutInitWindowSize(320,320);

win = glutCreateWindow("Bouncing disk");

glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);

glClearColor(0.5,0.0,0.8,1.0);

glutKeyboardFunc(quit);

glutTimerFunc(delay, animate, 0);

glutMainLoop();

return 0;

}

//---------- animate

void animate(int code)

{

disk();

glutTimerFunc(delay, animate, 0);

glutSwapBuffers();

}

//-------- disk