opengl: glutMainLoopEvent() only loop once

 

http://www.gamedev.net/topic/582980-freeglut-glutmainloopevent-wont-return/

while(1) glutMainLoopEvent();

seems only run once

Reason:

glutMainLoopEvent() seems only loop if 

there’s an gl event in same loop with it. 

E.g. the following code will seem to only loop once, 

instead of 100 times as specified

int main(int argc, char **argv) { 

    // init GLUT and create Window
    addPoints();
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowPosition(200,0);
    glutInitWindowSize(600,600);
    glutCreateWindow("Particle Simulator");
    glutDisplayFunc(display);
    glutIdleFunc(animation);
    glutKeyboardFunc (keyboard);
    glutSpecialFunc (keyboardSpecial); 

    for (int j=0; j < 100; j ++)
    {
        // enter GLUT event processing cycle
        glutMainLoopEvent();
    } 

    return 1; 

}

but the following will behave as expected 

(display will call many gl draw function hence seem to work):

int main(int argc, char **argv) {

    // init GLUT and create Window
    addPoints();
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowPosition(200,0);
    glutInitWindowSize(600,600);
    glutCreateWindow("Particle Simulator");
    glutIdleFunc(animation);
    glutKeyboardFunc (keyboard);
    glutSpecialFunc (keyboardSpecial);

    for (int j=0; j < 100; j ++)
    {
        // display to the screen
        display();

        // enter GLUT event processing cycle
        glutMainLoopEvent();
    }

    return 1;
}