Programming and Graphics

272 Introduction to C++ Programming and Graphics

#include <freeglut.h>

using namespace std;

void blank();

void print(int);

int delay=100; // in milliseconds

//--- main:

int main(int argc, char **argv)

{

int code=-1;

glutInit(&argc, argv);

glutInitDisplayMode(GLUTDEPTH | GLUTRGBA);

glutInitWindowPosition(100,100);

glutInitWindowSize(320,320);

glutCreateWindow("ASCII");

glOrtho(0, 100, 0, 100, 0, 100);

glClearColor(0.5,0.0,0.8,1.0);

glutDisplayFunc(blank);

glutTimerFunc(delay, print, code);

glutMainLoop();

return 0;

}

//--- Print:

void print (int code)

{

glClear(GLCOLORBUFFERBIT);

char a = code++;

glRasterPos2i(50, 50);

glutBitmapCharacter(GLUTBITMAP 8 BY13, a);

glFlush();

glutTimerFunc(delay, print, code);

delay=delay+1;

}

//--- Blank screen:

void blank()

{

glClear(GLCOLORBUFFERBIT);

}

Note that theglutTimerFuncfunction calls the user-defined functionprint,
which in turn callsglutTimerFuncin an infinite loop. In this case,printalso
changes the delay.