A display callback

Controls the display callback for the current window. When GLUT determines that the normal plane for the window needs to be redisplayed, the display callback for the window is called. Before the callback, the current window is set to the window needing to be redisplayed and (if no overlay display callback is registered) the layer in use is set to the normal plane. The entire normal plane region should be redisplayed in response to the callback (this includes ancillary buffers if your program depends on their state).

GLUT determines when the display callback should be triggered based on the window's redisplay state. The redisplay state for a window can be either set explicitly by calling postRedisplay or implicitly as the result of window damage reported by the window system. Multiple posted redisplays for a window are coalesced by GLUT to minimize the number of display callbacks called.

When an overlay is established for a window, but there is no overlay display callback registered, the display callback is used for redisplaying both the overlay and normal plane (that is, it will be called if either the redisplay state or overlay redisplay state is set). In this case, the layer in use is not implicitly changed on entry to the display callback.

See overlayDisplayCallback to understand how distinct callbacks for the overlay and normal plane of a window may be established.

When a window is created, no display callback exists for the window. It is the responsibility of the programmer to install a display callback for the window before the window is shown. A display callback must be registered for any window that is shown. If a window becomes displayed without a display callback being registered, a fatal error occurs. There is no way to "deregister" a display callback (though another callback routine can always be registered).

Upon return from the display callback, the normal damaged state of the window (see damaged) is cleared. If there is no overlay display callback registered the overlay damaged state of the window (see damaged) is also cleared.

Controls the overlay display callback for the current window. The overlay display callback is functionally the same as the window'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 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 postOverlayRedisplay 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 callbacks called.

Upon return from the overlay display callback, the overlay damaged state of the window (see damaged) is cleared.

Initially there is no overlay display callback registered when an overlay is established. See displayCallback to understand how the display callback alone is used if an overlay display callback is not registered.

A reshape callback

Controls the reshape callback for the current window. The reshape callback is triggered when a window is reshaped. A reshape callback is also triggered immediately before a window's first display callback after a window is created or whenever an overlay for the window is established. The parameter of the callback specifies the new window size in pixels. Before the callback, the current window is set to the window that has been reshaped.

If a reshape callback is not registered for a window or reshapeCallback is set to Nothing (to deregister a previously registered callback), the default reshape callback is used. This default callback will simply call

viewport (Position 0 0) (Size width height)

on the normal plane (and on the overlay if one exists).

If an overlay is established for the window, a single reshape callback is generated. It is the callback's responsibility to update both the normal plane and overlay for the window (changing the layer in use as necessary).

When a top-level window is reshaped, subwindows are not reshaped. It is up to the GLUT program to manage the size and positions of subwindows within a top-level window. Still, reshape callbacks will be triggered for subwindows when their size is changed using windowSize.

A position callback

(freeglut only) Controls the position callback for the current window. The position callback for a window is called when the position of a window changes.

The visibility state of the current window

A visibility callback

Controls the visibility callback for the current window. The visibility callback for a window is called when the visibility of a window changes.

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.

Note that you can either use visibilityCallback or windowStateCallback, but not both, because the former is implemented via the latter.

The window state of the current window

A window state callback

Controls the window state callback for the current window. The window state callback for a window is called when the window state of a window changes.

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

Note that you can either use visibilityCallback or windowStateCallback, but not both, because the former is implemented via the latter.

A window close callback

Controls the window close callback for the current window.

An initialize context callback

(freeglut only) Controls the initialize context callback for the /current window/.

The application status of the current window

An application status callback

Controls the application status callback for the current window.

A keyboard callback

Controls the keyboard callback for the current window. This is activated only when a key is pressed.

Controls the keyboard callback for the current window. This is activated only when a key is released.

A special key callback

Controls the special key callback for the current window. This is activated only when a special key is pressed.

Controls the special key callback for the current window. This is activated only when a special key is released.

A mouse callback

Controls the mouse callback for the current window.

A generalized view of keys

Special keys

Mouse buttons, including a wheel

The current state of a key or button

The state of the keyboard modifiers

A keyboard/mouse callback

Controls the keyboard/mouse callback for the current window. The keyboard/mouse callback for a window is called when the state of a key or mouse button changes. The callback parameters indicate the new state of the key/button, the state of the keyboard modifiers, and the mouse location in window relative coordinates.

Note that this is a convenience function that should not ordinarily be used in conjunction with keyboardCallback, keyboardUpCallback, specialCallback, specialUpCallback, or mouseCallback.

(freeglut only) Controls the mouse wheel callback for the current window. The mouse wheel callback for a window is called when a mouse wheel is used and the wheel number is greater than or equal to numMouseButtons.

A motion callback

Controls the motion callback for the current window. The motion callback for a window is called when the mouse moves within the window while one or more mouse buttons are pressed. The callback parameter indicates the mouse location in window relative coordinates.

Controls the passive motion callback for the current window. The passive motion callback for a window is called when the mouse moves within the window while no mouse buttons are pressed. The callback parameter indicates the mouse location in window relative coordinates.

The relation between the mouse pointer and the current window has changed.

An enter/leave callback

Controls the mouse enter/leave callback for the current window. Note that some window systems may not generate accurate enter/leave callbacks.

X Implementation Notes: An X implementation of GLUT should generate accurate enter/leave callbacks.

Translation of the Spaceball along one axis, normalized to be in the range of -1000 to +1000 inclusive

Rotation of the Spaceball along one axis, normalized to be in the range of -1800 .. +1800 inclusive

The index of a specific buttons of an input device.

The state of the Spaceball has changed.

A SpaceballButton callback

Controls the Spaceball callback for the current window. The Spaceball callback for a window is called when the window has Spaceball input focus (normally, when the mouse is in the window) and the user generates Spaceball translations, rotations, or button presses. The number of available Spaceball buttons can be determined with numSpaceballButtons.

Registering a Spaceball callback when a Spaceball device is not available has no effect and is not an error. In this case, no Spaceball callbacks will be generated.

The dial & button box state has changed.

The index of a specific dial of a dial and button box.

A dial & button box callback

Controls the dial & button box callback for the current window. The dial & button box button callback for a window is called when the window has dial & button box input focus (normally, when the mouse is in the window) and the user generates dial & button box button presses or dial changes. The number of available dial & button box buttons and dials can be determined with numDialsAndButtons.

Registering a dial & button box callback when a dial & button box device is not available is ineffectual and not an error. In this case, no dial & button box button will be generated.

Absolute tablet position, with coordinates normalized to be in the range of 0 to 2000 inclusive

The table state has changed.

A tablet callback

Controls the tablet callback for the current window. The tablet callback for a window is called when the window has tablet input focus (normally, when the mouse is in the window) and the user generates tablet motion or button presses. The number of available tablet buttons can be determined with numTabletButtons.

Registering a tablet callback when a tablet device is not available is ineffectual and not an error. In this case, no tablet callbacks will be generated.

The state of the joystick buttons

Absolute joystick position, with coordinates normalized to be in the range of -1000 to 1000 inclusive. The signs of the three axes mean the following:

• negative = left, positive = right
• negative = towards player, positive = away
• if available (e.g. rudder): negative = down, positive = up

A joystick callback

Controls the joystick callback for the current window. The joystick callback is called either due to polling of the joystick at the uniform timer interval specified (if > 0) or in response to an explicit call of forceJoystickCallback.

X Implementation Notes: Currently GLUT has no joystick support for X11.

A description where the multi-touch event is coming from, the freeglut specs are very vague about the actual semantics. It contains the device ID and/or the cursor/finger ID.

A multi-touch variant of MouseCallback.

(freeglut only) A multi-touch variant of mouseCallback.

A multi-touch variant of CrossingCallback.

(freeglut only) A multi-touch variant of crossingCallback.

A multi-touch variant of MotionCallback.

(freeglut only) A multi-touch variant of motionCallback.

(freeglut only) A multi-touch variant of passiveMotionCallback.