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glutIdleFunc(3GLUT)                                 GLUT                                 glutIdleFunc(3GLUT)



NAME
       glutIdleFunc - sets the global idle callback.

SYNTAX
       #include <GLUT/glut.h>

       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 pro-cessing processing
       cessing tasks or continuous animation when window system events are not being received.  If  enabled,
       the idle callback 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 affect-ing affecting
       ing  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 callback.

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 glutPostRedisplay.

       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  call-back callback
       back when the window first becomes visible on the screen.

SEE ALSO
       glutTimerFunc(3G), glutVisibilityFunc(3G)


AUTHOR
       Mark J. Kilgard (mjk@nvidia.com)



GLUT                                                 3.7                                 glutIdleFunc(3GLUT)