glutidlefunc(3glut) [osx man page]
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)
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glutOverlayDisplayFunc(3GLUT) GLUT glutOverlayDisplayFunc(3GLUT) NAME
glutOverlayDisplayFunc - sets the overlay display callback for the current window. SYNTAX
#include <GLUT/glut.h> void glutOverlayDisplayFunc(void (*func)(void)); ARGUMENTS
func The new overlay display callback function. DESCRIPTION
glutDisplayFunc sets the overlay display callback for the current window. The overlay display callback is functionally the same as the win- dow's display callback except that the overlay display callback is used to redisplay the window's overlay. When GLUT determines that the overlay plane for the window needs to be redisplayed, the overlay display callback for the window is called. Before the callback, the current window is set to the window needing to be redisplayed and the layer in use is set to the overlay. The overlay display callback is called with no parameters. The entire overlay region should be redisplayed in response to the callback (this includes ancillary buffers if your program depends on their state). GLUT determines when the overlay display callback should be triggered based on the window's overlay redisplay state. The overlay redisplay state for a window can be either set explicitly by calling glutPostOverlayRedisplay or implicitly as the result of window damage reported by the window system. Multiple posted overlay redisplays for a window are coalesced by GLUT to minimize the number of overlay display call- backs called. Upon return from the overlay display callback, the overlay damaged state of the window (returned by calling glutLayerGet(GLUT_OVERLAY_DAM- AGED) is cleared. The overlay display callback can be deregistered by passing NULL to glutOverlayDisplayFunc. The overlay display callback is initially NULL when an overlay is established. See glutDisplayFunc to understand how the display callback alone is used if an overlay display callback is not registered. SEE ALSO
glutDisplayFunc, glutPostOverlayRedisplay AUTHOR
Mark J. Kilgard (mjk@nvidia.com) GLUT
3.7 glutOverlayDisplayFunc(3GLUT)