glutIdleFunc(3GLUT) GLUT glutIdleFunc(3GLUT)
NAME
glutIdleFunc - sets the global idle callback.
SYNTAX
void glutIdleFunc(void (*func)(void));
ARGUMENTS
func The new idle callback function.
DESCRIPTION
glutIdleFunc sets the global idle callback to be func so a GLUT program
can perform background processing tasks or continuous animation when
window system events are not being received. If enabled, the idle call-
back is continuously called when events are not being received. The
callback routine has no parameters. The current window and current menu
will not be changed before the idle callback. Programs with multiple
windows and/or menus should explicitly set the current window and/or
current menu and not rely on its current setting.
The amount of computation and rendering done in an idle callback should
be minimized to avoid affecting the program's interactive response. In
general, not more than a single frame of rendering should be done in an
idle callback.
Passing NULL to glutIdleFunc disables the generation of the idle call-
back.
EXAMPLE
A typical idle callback to animate a window might look like:
void
idle(void)
{
time += 0.05;
glutSetWindow(window);
glutPostRedisplay();
}
Notice how the idle callback does not do any actual drawing; it only
advances the time scene state global variable. That is left to the
window's display callback which will be triggered by the call to glut-
PostRedisplay.
If you use the idle callback for animation, you should be sure to stop
rendering when the window is not visible. This is easy to set up with
a visibility callback. For example:
void
visible(int vis)
{
if (vis == GLUT_VISIBLE)
glutIdleFunc(idle);
else
glutIdleFunc(NULL);
}
If you do use the idle callback for animation, one thing you should not
do is setup the idle callback before calling glutMainLoop. It is much
better to use the visibility callback to install idle callback when the
window first becomes visible on the screen.
SEE ALSO
glutTimerFunc(3), glutVisibilityFunc(3)
AUTHOR
Mark J. Kilgard (mjk@nvidia.com)
GLUT 3.7 glutIdleFunc(3GLUT)
Mac OS X 10.6 - Generated Thu Sep 17 20:20:40 CDT 2009