glutvisibilityfunc(3glut) [redhat man page]

glutVisibilityFunc(3GLUT)					       GLUT						 glutVisibilityFunc(3GLUT)

NAME

       glutVisibilityFunc - sets the visibility callback for the current window.

SYNTAX

       void glutVisibilityFunc(void (*func)(int state));

ARGUMENTS

       func	 The new visibility callback function.

DESCRIPTION

       glutVisibilityFunc  sets the visibility callback for the current window. The visibility callback for a window is called when the visibility
       of a window changes. The state callback parameter is either GLUT_NOT_VISIBLE or GLUT_VISIBLE depending on the  current  visibility  of  the
       window.	GLUT_VISIBLE does not distinguish a window being totally versus partially visible. GLUT_NOT_VISIBLE means no part of the window is
       visible, i.e., until the window's visibility changes, all further rendering to the window is discarded.

       GLUT considers a window visible if any pixel of the window is visible or any pixel of any descendant window is visible on the screen.

       Passing NULL to glutVisibilityFunc disables the generation of the visibility callback.

       If the visibility callback for a window is disabled and later re-enabled, the visibility status of the window is undefined; any	change	in
       window  visibility  will  be reported, that is if you disable a visibility callback and re-enable the callback, you are guaranteed the next
       visibility change will be reported.

SEE ALSO

       glutCreateWindow, glutPopWindow

AUTHOR

       Mark J. Kilgard (mjk@nvidia.com)

GLUT
									3.7						 glutVisibilityFunc(3GLUT)

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 processing 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 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 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 callback when the window first becomes visible on the screen.

SEE ALSO

       glutTimerFunc, glutVisibilityFunc

AUTHOR

       Mark J. Kilgard (mjk@nvidia.com)

GLUT
									3.7						       glutIdleFunc(3GLUT)