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FREEGLUT Application Program Interface
The Open-Source
OpenGL Utility Toolkit
(freeglut 2.0.0)
Application Programming Interface
Version 4.0
The freeglut Programming Consortium
July, 2003
OpenGL is a trademark of Silicon Graphics, Inc. X Window System is a trademark
of X Consortium, Inc. Spaceball is a registered trademark of Spatial
Systems Inc.
The authors have taken care in preparation of this documentation but make
no expressed or implied warranty of any kind and assumes no responsibility
for errors or omissions. No liability is assumed for incidental or consequential
damages in connection with or arising from the use of information or programs
contained herein.
1.0
Contents
1.0 Contents
2.0 Introduction
3.0 Background
3.1 Design Philosophy
3.2 Conventions
3.3 Terminology
3.4 Differences from GLUT 3.7
4.0 Initialization Functions
4.1 glutInit
4.2 glutInitWindowPosition, glutInitWindowSize
4.3 glutInitDisplayMode
4.4 glutInitDisplayString
5.0 Event Processing Functions
5.1 glutMainLoop
5.2 glutMainLoopEvent
5.3 glutLeaveMainLoop
6.0 Window Functions
6.1 glutCreateWindow
6.2 glutCreateSubwindow
6.3 glutDestroyWindow
6.4 glutSetWindow, glutGetWindow
6.5 glutSetWindowTitle, glutSetIconTitle
6.6 glutReshapeWindow
6.7 glutPositionWindow
6.8 glutShowWindow, glutHideWindow, glutIconifyWindow
6.9 glutPushWindow, glutPopWindow
6.10 glutFullScreen
7.0 Display Functions
7.1 glutPostRedisplay
7.2 glutPostWindowRedisplay
7.3 glutSwapBuffers
8.0 Mouse Cursor Functions
8.1 glutSetCursor
8.2 glutWarpPointer
9.0 Overlay Functions
9.1 glutEstablishOverlay
9.2 glutRemoveOverlay
9.3 glutUseLayer
9.4 glutPostOverlayRedisplay
9.5 glutPostWindowOverlayRedisplay
9.6 glutShowOverlay, glutHideOverlay
10.0 Menu Functions
10.1 glutCreateMenu
10.2 glutDestroyMenu
10.3 glutGetMenu, glutSetMenu
10.4 glutAddMenuEntry
10.5 glutAddSubMenu
10.6 glutChangeToMenuEntry
10.7 glutChangeToSubMenu
10.8 glutRemoveMenuItem
10.9 glutAttachMenu, glutDetachMenu
11.0 Global Callback Registration Functions
11.1 glutTimerFunc
11.2 glutIdleFunc
12.0 Window-Specific Callback Registration
Functions
12.1 glutDisplayFunc
12.2 glutOverlayDisplayFunc
12.3 glutReshapeFunc
12.4 glutCloseFunc
12.5 glutKeyboardFunc
12.6 glutSpecialFunc
12.7 glutKeyboardUpFunc
12.8 glutSpecialUpFunc
12.9 glutMouseFunc
12.10 glutMotionFunc, glutPassiveMotionFunc
12.11 glutVisibilityFunc
12.12 glutEntryFunc
12.13 glutJoystickFunc
12.14 glutSpaceballMotionFunc
12.15 glutSpaceballRotateFunc
12.16 glutSpaceballButtonFunc
12.17 glutButtonBoxFunc
12.18 glutDialsFunc
12.19 glutTabletMotionFunc
12.20 glutTabletButtonFunc
12.21 glutMenuStatusFunc
12.22 glutWindowStatusFunc
13.0 State Setting and Retrieval Functions
13.1 glutSetOption
13.2 glutGet
13.3 glutDeviceGet
13.4 glutGetModifiers
13.5 glutLayerGet
13.6 glutExtensionSupported
13.7 glutGetProcAddress
14.0 Font Rendering Functions
14.1 glutBitmapCharacter
14.2 glutBitmapString
14.3 glutBitmapWidth
14.4 glutBitmapLength
14.5 glutBitmapHeight
14.6 glutStrokeCharacter
14.7 glutStrokeString
14.8 glutStrokeWidth
14.9 glutStrokeLength
14.10 glutStrokeHeight
15.0 Geometric Object Rendering Functions
15.1 glutWireSphere, glutSolidSphere
15.2 glutWireTorus, glutSolidTorus
15.3 glutWireCone, glutSolidCone
15.4 glutWireCube, glutSolidCube
15.5 glutWireTetrahedron, glutSolidTetrahedron
15.6 glutWireOctahedron, glutSolidOctahedron
15.7 glutWireDodecahedron, glutSolidDodecahedron
15.8 glutWireIcosahedron, glutSolidIcosahedron
15.9 glutWireRhombicDodecahedron, glutSolidRhombicDodecahedron
15.10 glutWireTeapot, glutSolidTeapot
16.0 Game Mode Functions
16.1 glutGameModeString
16.2 glutEnterGameMode, glutLeaveGameMode
16.3 glutGameModeGet
17.0 Video Resize Functions
17.1 glutVideoResizeGet
17.2 glutSetupVideoResizing, glutStopVideoResizing
17.3 glutVideoResize
17.4 glutVideoPan
18.0 Color Map Functions
18.1 glutSetColor, glutGetColor
18.2 glutCopyColormap
19.0 Miscellaneous Functions
19.1 glutIgnoreKeyRepeat,
glutSetKeyRepeat
19.2 glutForceJoystickFunc
19.3 glutReportErrors
20.0 Usage Notes
21.0
Implementation Notes
22.0 GLUT
State
23.0
"freeglut.h" Header File
24.0 References
25.0 Index
2.0
Introduction
3.0
Background
The OpenGL programming world owes a tremendous debt to Mr. Mark J. Kilgard
for writing the OpenGL Utility Toolkit, or GLUT. The GLUT library
of functions allows an application programmer to create, control, and manipulate
windows independent of what operating system the program is running on.
By hiding the dependency on the operating system from the application programmer,
he allowed people to write truly portable OpenGL applications.
Mr. Kilgard copyrighted
his library and gave it a rather unusual license. Under his license,
people are allowed freely to copy and distribute the libraries and the source
code, but they are not allowed to modify it. For a long time this did
not matter because the GLUT library worked so well and because Mr. Kilgard
was releasing updates on a regular basis. But with the passage of time,
people started wanting some slightly different behaviours in their windowing
system. When Mr. Kilgard stopped supporting the GLUT library in 1999,
having moved on to bigger and better things, this started to become a problem.
In December 1999,
Mr. Pawel Olzsta started work on an open-source clone of the GLUT library.
This open-source clone, which does not use any of the GLUT source code, has
evolved into the present freeglut library. This documentation
specifies the application program interface to the freeglut library.
3.1 Design Philosophy
3.2 Conventions
3.3 Terminology
3.4 Differences from GLUT 3.7
Since the freeglut library was developed in order to update GLUT,
it is natural that there will be some differences between the two.
Each function in the API notes any differences between the GLUT and the
freeglut function behaviours. The important ones are summarized
here.
3.4.1 glutMainLoop Behaviour
One of the commonest complaints about the GLUT library was that once an
application called "glutMainLoop", it never got control back.
There was no way for an application to loop in GLUT for a while, possibly
as a subloop while a specific window was open, and then return to the calling
function. A new function, "glutMainLoopEvent", has been added
to allow this functionality. Another function, "glutLeaveMainLoop
", has also been added to allow the application to tell freeglut to clean
up and close down.
3.4.2 Action on Window Closure
Another difficulty with GLUT, especially with multiple-window programs,
is that if the user clicks on the "x" in the window header the application
exits immediately. The application programmer can now set an option,
" GLUT_ACTION_ON_WINDOW_CLOSE", to specify whether execution should
continue, whether GLUT should return control to the main program, or whether
GLUT should simply exit (the default).
3.4.3 Changes to Callbacks
Several new callbacks have been added and several callbacks which were specific
to Silicon Graphics hardware have not been implemented. Most or all
of the new callbacks are listed in the GLUT Version 4 "glut.h" header file
but did not make it into the documentation. The new callbacks consist
of regular and special key release callbacks, a joystick callback, a menu
state callback (with one argument, distinct from the menu status callback
which has three arguments), and a window status callback
(also with one argument). Unsupported callbacks are the three Spaceball
callbacks, the ButtonBox callback, the Dials callback, and the two Tablet
callbacks. If the user has a need for an unsupported callback he should
contact the freeglut development team.
3.4.4 String Rendering
New functions have been added to render full character strings (including
carriage returns) rather than rendering one character at a time. More
functions return the widths of character strings and the font heights, in
pixels for bitmapped fonts and in OpenGL units for the stroke fonts.
3.4.5 Geometry Rendering
Two functions have been added to render a wireframe and a solid rhombic
dodecahedron.
3.4.5 Extension Function Queries
glutGetProcAddress is a wrapper for the glXGetProcAddressARB and wglGetProcAddress
functions.
4.0
Initialization Functions
4.1 glutInit
4.2 glutInitWindowPosition, glutInitWindowSize
The "glutInitWindowPosition " and "glutInitWindowSize
" functions specify a desired position and size for windows that freeglut
will create in the future.
Usage
void glutInitWindowPosition ( int
x, int y ) ;
void glutInitWindowSize ( int width,
int height ) ;
Description
The "glutInitWindowPosition
" and "glutInitWindowSize" functions specify a desired position
and size for windows that freeglut will create in the future.
The position is measured in pixels from the upper left hand corner of the
screen, with "x" increasing to the right and "y" increasing towards the bottom
of the screen. The size is measured in pixels. Freeglut
does not promise to follow these specifications in creating its windows,
it certainly makes an attempt to.
The position and size of a window are
a matter of some subtlety. Most windows have a usable area surrounded
by a border and with a title bar on the top. The border and title bar
are commonly called "decorations." The position of the window unfortunately
varies with the operating system. On Linux, it is the coordinates of
the upper left-hand corner of its decorations. On Windows, it is the
coordinates of the upper left hand corner of its usable interior. For
both operating systems, the size of the window is the size of the usable interior.
Windows has some additional quirks which
the application programmer should know about. First, the minimum y-coordinate
of a window decoration is zero. (This is a feature of freeglut
and can be adjusted if so desired.) Second, there appears to be a
minimum window width on Windows which is 104 pixels. The user may specify
a smaller width, but the Windows system calls ignore it. It is also
impossible to make a window narrower than this by dragging on its corner.
Changes From GLUT
For some reason, GLUT is not affected
by the 104-pixel minimum window width. If the user clicks on the corner
of a window which is narrower than this amount, the window will immediately
snap out to this width, but the application can call "glutReshapeWindow
" and make a window narrower again.
4.3 glutInitDisplayMode
4.4 glutInitDisplayString
5.0
Event Processing Functions
After an application has finished initializing its windows and menus, it
enters an event loop. Within this loop, freeglut polls the
data entry devices (keyboard, mouse, etc.) and calls the application's appropriate
callbacks.
In GLUT, control never returned from
the event loop (as invoked by the "glutMainLoop" function) to the
calling function. This prevented an application from having re-entrant
code, in which GLUT could be invoked from within a callback, and it prevented
the application from doing any post-processing (such as freeing allocated
memory) after GLUT had closed down. Freeglut allows the application
programmer to specify more direct control over the event loop by means of
two new functions. The first, "glutMainLoopEvent", processes
a single iteration of the event loop and allows the application to use a different
event loop controller or to contain re-entrant code. The second, "
glutLeaveMainLoop", causes the event loop to exit nicely; this is preferable
to the application's calling "exit" from within a GLUT callback.
5.1 glutMainLoop
The "glutMainLoop" function enters the event loop.
Usage
void glutMainLoop ( void ) ;
Description
The "glutMainLoop" function
causes the program to enter the window event loop. An application should
call this function at most once. It will call any application callback
functions as required to process mouse clicks, mouse motion, key presses,
and so on.
Changes From GLUT
In GLUT, there was absolutely no way
for the application programmer to have control return from the "glutMainLoop
" function to the calling function. Freeglut allows the programmer
to force this by setting the "GLUT_ACTION_ON_WINDOW_CLOSE" option
and invoking the "glutLeaveMainLoop" function from one of the callbacks.
Stopping the program this way is preferable to simply calling "exit
" from within a callback because this allows freeglut to free allocated
memory and otherwise clean up after itself. (I know I just said this,
but I think it is important enough that it bears repeating.)
5.2 glutMainLoopEvent
The "glutMainLoopEvent" function processes a single iteration
in the freeglut event loop.
Usage
void glutMainLoopEvent ( void ) ;
Description
The "glutMainLoopEvent
" function causes freeglut to process one iteration's worth of events
in its event loop. This allows the application to control its own event
loop and still use the freeglut windowing system.
Changes From GLUT
GLUT does not include this function.
5.3 glutLeaveMainLoop
The "glutLeaveMainLoop" function causes freeglut to stop
its event loop.
Usage
void glutLeaveMainLoop ( void ) ;
Description
The "glutLeaveMainLoop
" function causes freeglut to stop the event loop. If the
" GLUT_ACTION_ON_WINDOW_CLOSE" option has been set to "GLUT_ACTION_CONTINUE_EXECUTION
", control will return to the function which called "glutMainLoop
"; otherwise the application will exit.
If the application has two nested calls
to "glutMainLoop" and calls "glutLeaveMainLoop", the behaviour
of freeglut is undefined. It may leave only the inner nested
loop or it may leave both loops. If the reader has a strong preference
for one behaviour over the other he should contact the freeglut Programming
Consortium and ask for the code to be fixed.
Changes From GLUT
GLUT does not include this function.
6.0
Window Functions
6.1 glutCreateWindow
6.2 glutCreateSubwindow
6.3 glutDestroyWindow
6.4 glutSetWindow, glutGetWindow
6.5 glutSetWindowTitle, glutSetIconTitle
6.6 glutReshapeWindow
6.7 glutPositionWindow
6.8 glutShowWindow, glutHideWindow,
glutIconifyWindow
6.9 glutPushWindow, glutPopWindow
6.10 glutFullScreen
7.0
Display Functions
7.1 glutPostRedisplay
7.2 glutPostWindowRedisplay
7.3 glutSwapBuffers
8.0
Mouse Cursor Functions
8.1 glutSetCursor
8.2 glutWarpPointer
9.0
Overlay Functions
Freeglut does not allow overlays, although it does "answer the mail"
with function stubs so that GLUT-based programs can compile and link against
freeglut without modification.
If the reader needs overlays, he should contact the freeglut Programming
Consortium and ask for them to be implemented. He should also be prepared
to assist in the implementation.
9.1 glutEstablishOverlay
The "glutEstablishOverlay" function is not implemented in freeglut
.
Usage
void glutEstablishOverlay ( void
) ;
Description
The "glutEstablishOverlay" function
is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
9.2 glutRemoveOverlay
The "glutRemoveOverlay" function is not implemented in freeglut
.
Usage
void glutRemoveOverlay ( void ) ;
Description
The "glutRemoveOverlay" function
is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
9.3 glutUseLayer
The "glutUseLayer" function is not implemented in freeglut
.
Usage
void glutUseLayer ( GLenum
layer ) ;
Description
The "glutUseLayer" function
is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
9.4 glutPostOverlayRedisplay
The "glutPostOverlayRedisplay " function is not implemented in
freeglut.
Usage
void glutPostOverlayRedisplay ( void
) ;
Description
The "glutPostOverlayRedisplay
" function is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
9.5 glutPostWindowOverlayRedisplay
The "glutPostWindowOverlayRedisplay " function is not implemented
in freeglut.
Usage
void glutPostWindowOverlayRedisplay
( int window ) ;
Description
The "glutPostWindowOverlayRedisplay
" function is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
9.6 glutShowOverlay, glutHideOverlay
The "glutShowOverlay" and "glutHideOverlay" functions
are not implemented in freeglut .
Usage
void glutShowOverlay( void ) ;
void glutHideOverlay( void ) ;
Description
The "glutShowOverlay" and "
glutHideOverlay" functions are not implemented in freeglut .
Changes From GLUT
GLUT implements these functions.
10.0
Menu Functions
10.1 glutCreateMenu
10.2 glutDestroyMenu
10.3 glutGetMenu, glutSetMenu
10.4 glutAddMenuEntry
10.5 glutAddSubMenu
10.6 glutChangeToMenuEntry
10.7 glutChangeToSubMenu
10.8 glutRemoveMenuItem
10.9 glutAttachMenu, glutDetachMenu
11.0
Global Callback Registration Functions
11.1 glutTimerFunc
11.2 glutIdleFunc
The "glutIdleFunc" function sets the global idle callback.
Freeglut calls the idle callback when there are no inputs from the user.
Usage
void glutIdleFunc ( void (*func)
( void ) ) ;
func The new
global idle callback function
Description
The "glutIdleFunc" function
specifies the function that freeglut will call to perform background
processing tasks such as continuous animation when window system events are
not being received. If enabled, this function is called continuously
from freeglut while no events are received. The callback function
has no parameters and returns no value. Freeglut does not change
the current window or the current menu before invoking the idle
callback; programs with multiple windows or menus must explicitly set the
current window and 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, no more than a single frame of rendering should
be done in a single invocation of an idle callback.
Calling "glutIdleFunc" with a NULL argument
disables the call to an idle callback.
Changes From GLUT
Application programmers should note that
if they have specified the "continue execution" action on window closure,
freeglut will continue to call the
idle callback after the user has closed a window by clicking on the "x" in
the window header bar. If the idle callback renders a particular window
(this is considered bad form but is frequently done anyway), the programmer
should supply a window closure callback for that window which changes or disables
the idle callback.
12.0
Window-Specific Callback Registration Functions
12.1 glutDisplayFunc
12.2 glutOverlayDisplayFunc
12.3 glutReshapeFunc
12.4 glutCloseFunc
12.5 glutKeyboardFunc
12.6 glutSpecialFunc
The "glutSpecialFunc" function sets the window's special key press
callback. Freeglut calls the special key press callback when the
user presses a special key.
Usage
void glutSpecialFunc ( void (*func)
( int key, int x, int y ) ) ;
func The window's
new special key press callback function
key The
key whose press triggers the callback
x
The x-coordinate of the mouse relative
to the window at the time the key is pressed
y
The y-coordinate of the mouse relative
to the window at the time the key is pressed
Description
The "glutSpecialFunc"
function specifies the function that freeglut will call when the user
presses a special key on the keyboard. The callback function has one
argument: the name of the function to be invoked ("called back") at
the time at which the special key is pressed. The function returns no
value. Freeglut sets the current window to the window
which is active when the callback is invoked. "Special keys" are the
function keys, the arrow keys, the Page Up and Page Down keys, and the Insert
key. The Delete key is considered to be a regular key.
Calling "glutSpecialUpFunc" with a NULL argument
disables the call to the window's special key press callback.
The "key
" argument may take one of the following defined constant values:
- GLUT_KEY_F1, GLUT_KEY_F2, ..., GLUT_KEY_F12
- F1 through F12 keys
- GLUT_KEY_PAGE_UP, GLUT_KEY_PAGE_DOWN
- Page Up and Page Down keys
- GLUT_KEY_HOME, GLUT_KEY_END
- Home and End keys
- GLUT_KEY_LEFT, GLUT_KEY_RIGHT, GLUT_KEY_UP, GLUT_KEY_DOWN
- arrow keys
- GLUT_KEY_INSERT
- Insert key
Changes From GLUT
None.
12.7 glutKeyboardUpFunc
The "glutKeyboardUpFunc" function sets the window's key release
callback. Freeglut calls the key release callback when the user releases
a key.
Usage
void glutKeyboardUpFunc ( void (*func)
( unsigned char key, int x, int y ) ) ;
func The window's
new key release callback function
key The
key whose release triggers the callback
x
The x-coordinate of the mouse relative
to the window at the time the key is released
y
The y-coordinate of the mouse relative
to the window at the time the key is released
Description
The "glutKeyboardUpFunc
" function specifies the function that freeglut will call when the
user releases a key from the keyboard. The callback function has one
argument: the name of the function to be invoked ("called back") at
the time at which the key is released. The function returns no value.
Freeglut sets the current window
to the window which is active when the callback is invoked.
While freeglut checks for upper or lower case
letters, it does not do so for non-alphabetical characters. Nor does
it account for the Caps-Lock key being on. The operating system may
send some unexpected characters to freeglut, such as "8" when the
user is pressing the Shift key. Freeglut also invokes the callback
when the user releases the Control, Alt, or Shift keys, among others.
Releasing the Delete key causes this function to be invoked with a value
of 127 for "key".
Calling "glutKeyboardUpFunc" with a NULL argument
disables the call to the window's key release callback.
Changes From GLUT
This function is not implemented in GLUT
versions before Version 4. It has been designed to be as close to GLUT
as possible. Users who find differences should contact the
freeglut Programming Consortium to
have them fixed.
12.8 glutSpecialUpFunc
The "glutSpecialUpFunc" function sets the window's special key
release callback. Freeglut calls the special key release callback
when the user releases a special key.
Usage
void glutSpecialUpFunc ( void (*func)
( int key, int x, int y ) ) ;
func The window's
new special key release callback function
key The
key whose release triggers the callback
x
The x-coordinate of the mouse relative
to the window at the time the key is released
y
The y-coordinate of the mouse relative
to the window at the time the key is released
Description
The "glutSpecialUpFunc
" function specifies the function that freeglut will call when the
user releases a special key from the keyboard. The callback function
has one argument: the name of the function to be invoked ("called back")
at the time at which the special key is released. The function returns
no value. Freeglut sets the current window to the window
which is active when the callback is invoked. "Special keys" are the
function keys, the arrow keys, the Page Up and Page Down keys, and the Insert
key. The Delete key is considered to be a regular key.
Calling "glutSpecialUpFunc" with a NULL argument
disables the call to the window's special key release callback.
The "key
" argument may take one of the following defined constant values:
- GLUT_KEY_F1, GLUT_KEY_F2, ..., GLUT_KEY_F12
- F1 through F12 keys
- GLUT_KEY_PAGE_UP, GLUT_KEY_PAGE_DOWN
- Page Up and Page Down keys
- GLUT_KEY_HOME, GLUT_KEY_END
- Home and End keys
- GLUT_KEY_LEFT, GLUT_KEY_RIGHT, GLUT_KEY_UP, GLUT_KEY_DOWN
- arrow keys
- GLUT_KEY_INSERT
- Insert key
Changes From GLUT
This function is not implemented in GLUT
versions before Version 4. It has been designed to be as close to GLUT
as possible. Users who find differences should contact the
freeglut Programming Consortium to
have them fixed.
12.9 glutMouseFunc
12.10 glutMotionFunc, glutPassiveMotionFunc
12.11 glutVisibilityFunc
12.12 glutEntryFunc
12.13 glutJoystickFunc
12.14 glutSpaceballMotionFunc
The "glutSpaceballMotionFunc" function is not implemented in
freeglut, although the library does
"answer the mail" to the extent that a call to the function will not produce
an error..
Usage
void glutSpaceballMotionFunc ( void
(* callback)( int x, int y, int z ) ) ;
Description
The "glutSpaceballMotionFunc
" function is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.15 glutSpaceballRotateFunc
The "glutSpaceballRotateFunc" function is not implemented in
freeglut, although the library does
"answer the mail" to the extent that a call to the function will not produce
an error..
Usage
void glutSpaceballRotateFunc ( void
(* callback)( int x, int y, int z ) ) ;
Description
The "glutSpaceballRotateFunc
" function is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.16 glutSpaceballButtonFunc
The "glutSpaceballButtonFunc" function is not implemented in
freeglut, although the library does
"answer the mail" to the extent that a call to the function will not produce
an error..
Usage
void glutSpaceballButtonFunc ( void
(* callback)( int button, int updown ) ) ;
Description
The "glutSpaceballButtonFunc
" function is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.17 glutButtonBoxFunc
The "glutSpaceballButtonBoxFunc" function is not implemented
in freeglut, although the library does "answer the mail" to the extent
that a call to the function will not produce an error..
Usage
void glutSpaceballButtonBoxFunc (
void (* callback)( int button, int updown ) ) ;
Description
The "glutSpaceballButtonBoxFunc
" function is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.18 glutDialsFunc
The "glutDialsFunc" function is not implemented in freeglut
, although the library does "answer the mail" to the extent that a call
to the function will not produce an error..
Usage
void glutDialsFunc ( void (* callback)(
int dial, int value ) ) ;
Description
The "glutDialsFunc" function
is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.19 glutTabletMotionFunc
The "glutTabletMotionFunc" function is not implemented in
freeglut, although the library does "answer the mail" to the extent
that a call to the function will not produce an error..
Usage
void glutTabletMotionFunc ( void
(* callback)( int x, int y ) ) ;
Description
The "glutTabletMotionFunc" function
is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.20 glutTabletButtonFunc
The "glutTabletButtonFunc" function is not implemented in
freeglut, although the library does "answer the mail" to the extent
that a call to the function will not produce an error..
Usage
void glutTabletButtonFunc ( void
(* callback)( int button, int updown, int x, int y ) ) ;
Description
The "glutTabletButtonFunc" function
is not implemented in freeglut.
Changes From GLUT
GLUT implements this function.
12.21 glutMenuStatusFunc
12.22 glutWindowStatusFunc
13.0
State Setting and Retrieval Functions
13.1 glutSetOption
13.2 glutGet
The following state variables may be queried with "glutGet".
The returned value is an integer.
These queries are with respect to the current window:
- GLUT_WINDOW_X - window X position
- GLUT_WINDOW_Y - window Y position
- GLUT_WINDOW_WIDTH - window width
- GLUT_WINDOW_HEIGHT - window height
- GLUT_WINDOW_BUFFER_SIZE - number of color or color index bits per pixel
- GLUT_WINDOW_STENCIL_SIZE - number of bits per stencil value
- GLUT_WINDOW_DEPTH_SIZE - number of bits per depth value
- GLUT_WINDOW_RED_SIZE - number of bits per red value
- GLUT_WINDOW_GREEN_SIZE - number of bits per green value
- GLUT_WINDOW_BLUE_SIZE - number of bits per blue value
- GLUT_WINDOW_ALPHA_SIZE - number of bits per alpha value
- GLUT_WINDOW_ACCUM_RED_SIZE - number of red bits in the accumulation buffer
- GLUT_WINDOW_ACCUM_GREEN_SIZE - number of green bits in the accumulation buffer
- GLUT_WINDOW_ACCUM_BLUE_SIZE - number of blue bits in the accumulation buffer
- GLUT_WINDOW_ACCUM_ALPHA_SIZE - number of alpha bits in the accumulation buffer
- GLUT_WINDOW_DOUBLEBUFFER - 1 if the color buffer is double buffered, 0 otherwise
- GLUT_WINDOW_RGBA - 1 if the color buffers are RGB[A], 0 for color index
- GLUT_WINDOW_PARENT - parent window ID
- GLUT_WINDOW_NUM_CHILDREN - number of child windows
- GLUT_WINDOW_COLORMAP_SIZE - number of entries in the window's colormap
- GLUT_WINDOW_NUM_SAMPLES - number of samples per pixel if using multisampling
- GLUT_WINDOW_STEREO - 1 if the window supports stereo, 0 otherwise
- GLUT_WINDOW_CURSOR - current cursor
- GLUT_WINDOW_FORMAT_ID - on Windows, return the pixel format number of the current window
These queries do not depend on the current window.
- GLUT_SCREEN_WIDTH - width of the screen in pixels
- GLUT_SCREEN_HEIGHT - height of the screen in pixels
- GLUT_SCREEN_WIDTH_MM - width of the screen in millimeters
- GLUT_SCREEN_HEIGHT_MM - height of the screen in millimeters
- GLUT_MENU_NUM_ITEMS - number of items in the current menu
- GLUT_DISPLAY_MODE_POSSIBLE - return 1 if the current display mode is supported, 0 otherwise
- GLUT_INIT_WINDOW_X - X position last set by glutInitWindowPosition
- GLUT_INIT_WINDOW_Y - Y position last set by glutInitWindowPosition
- GLUT_INIT_WINDOW_WIDTH - width last set by glutInitWindowSize
- GLUT_INIT_WINDOW_HEIGHT - height last set by glutInitWindowSize
- GLUT_INIT_DISPLAY_MODE - display mode last set by glutInitDisplayMode
- GLUT_ELAPSED_TIME - time (in milliseconds) elapsed since glutInit or glutGet(GLUT_ELAPSED_TIME) was first called
- GLUT_INIT_STATE - ?
- GLUT_VERSION - Return value will be X*10000+Y*100+Z where X is the
major version, Y is the minor version and Z is the patch level.
This query is only supported in freeglut (version 2.0.0 or later).
13.3 glutDeviceGet
13.4 glutGetModifiers
13.5 glutLayerGet
13.6 glutExtensionSupported
13.7 glutGetProcAddress
glutGetProcAddress returns
a pointer to a named GL or freeglut function.
Usage
void *glutGetProcAddress ( const
char *procName ) ;
procName
Name of an OpenGL or GLUT function.
Description
glutGetProcAddress is useful
for dealing with OpenGL extensions. If an application calls OpenGL extension
functions directly, that application will only link/run with an OpenGL library
that supports the extension. By using a function pointer returned from glutGetProcAddress(),
the application will avoid this hard dependency and be more portable and interoperate
better with various implementations of OpenGL.
Both OpenGL functions and freeglut
functions can be queried with this function.
Changes From GLUT
GLUT does not include this function.
14.0
Font Rendering Functions
Freeglut supports two types of font rendering: bitmap fonts,
which are rendered using the "glBitmap" function call, and stroke
fonts, which are rendered as sequences of OpenGL line segments. Because
they are rendered as bitmaps, the bitmap fonts tend to render more quickly
than stroke fonts, but they are less flexible in terms of scaling and rendering.
Bitmap font characters are positioned with calls to the "glRasterPos*
" functions while stroke font characters use the OpenGL transformations
to position characters.
It should be noted
that freeglut fonts are similar but not identical to GLUT fonts.
At the moment, freeglut fonts do not support the "`" (backquote) and
"|" (vertical line) characters; in their place it renders asterisks.
Freeglut supports
the following bitmap fonts:
- GLUT_BITMAP_8_BY_13 - A variable-width font with every character
fitting in a rectangle of 13 pixels high by at most 8 pixels wide.
- GLUT_BITMAP_9_BY_15 - A variable-width font with every character
fitting in a rectangle of 15 pixels high by at most 9 pixels wide.
- GLUT_BITMAP_TIMES_ROMAN_10 - A 10-point variable-width Times
Roman font.
- GLUT_BITMAP_TIMES_ROMAN_24 - A 24-point variable-width Times
Roman font.
- GLUT_BITMAP_HELVETICA_10 - A 10-point variable-width Helvetica
font.
- GLUT_BITMAP_HELVETICA_12 - A 12-point variable-width Helvetica
font.
- GLUT_BITMAP_HELVETICA_18 - A 18-point variable-width Helvetica
font.
Freeglut calls "glRasterPos4v" to advance the cursor by
the width of a character and to render carriage returns when appropriate.
It does not use any display lists in it rendering in bitmap fonts.
Freeglut supports
the following stroke fonts:
- GLUT_STROKE_ROMAN - A proportionally-spaced Roman Simplex
font
- GLUT_STROKE_MONO_ROMAN - A fixed-width Roman Simplex font
Freeglut does not use any display lists in its rendering of stroke
fonts. It calls "glTranslatef" to advance the cursor by the
width of a character and to render carriage returns when appropriate.
14.1 glutBitmapCharacter
The "glutBitmapCharacter" function renders a single bitmapped
character in the current window using the specified font.
Usage
void glutBitmapCharacter ( void *font,
int character ) ;
font
The bitmapped font to use in rendering
the character
character The ASCII
code of the character to be rendered
Description
The "glutBitmapCharacter
" function renders the given character in the specified bitmap font.
Freeglut automatically sets the necessary
pixel unpack storage modes and restores the existing modes when it has finished.
Before the first call to "glutBitMapCharacter " the application
program should call "glRasterPos*" to set the position of the character
in the window. The "glutBitmapCharacter " function advances
the cursor position as part of its call to "glBitmap " and so the
application does not need to call "glRasterPos*" again for successive
characters on the same line.
Changes From GLUT
Nonexistent characters are rendered as
asterisks. The rendering position in freeglut is apparently off
from GLUT's position by a few pixels vertically and one or two pixels horizontally.
14.2 glutBitmapString
The "glutBitmapString" function renders a string of bitmapped
characters in the current window using the specified font.
Usage
void glutBitmapString ( void *font,
char *string ) ;
font
The bitmapped font to use in rendering
the character string
string String
of characters to be rendered
Description
The "glutBitmapString
" function renders the given character string in the specified bitmap font.
Freeglut automatically sets the necessary
pixel unpack storage modes and restores the existing modes when it has finished.
Before calling "glutBitMapString" the application program should
call "glRasterPos*" to set the position of the string in the window.
The "glutBitmapString" function handles carriage returns.
Nonexistent characters are rendered as asterisks.
Changes From GLUT
GLUT does not include this function.
14.3 glutBitmapWidth
The "glutBitmapWidth" function returns the width in pixels of
a single bitmapped character in the specified font.
Usage
int glutBitmapWidth ( void *font,
int character ) ;
font
The bitmapped font to use in calculating
the character width
character The ASCII
code of the character
Description
The "glutBitmapWidth"
function returns the width of the given character in the specified bitmap
font. Because the font is bitmapped, the width is an exact integer.
Changes From GLUT
Nonexistent characters return the width
of an asterisk.
14.4 glutBitmapLength
The "glutBitmapLength" function returns the width in pixels of
a string of bitmapped characters in the specified font.
Usage
int glutBitmapLength ( void *font,
char *string ) ;
font The bitmapped
font to use in calculating the character width
string String of characters
whose width is to be calculated
Description
The "glutBitmapLength
" function returns the width in pixels of the given character string in
the specified bitmap font. Because the font is bitmapped, the width
is an exact integer: the return value is identical to the sum of the
character widths returned by a series of calls to "glutBitmapWidth
". The width of nonexistent characters is counted to be the width of
an asterisk.
If the string contains
one or more carriage returns, freeglut calculates the widths in pixels
of the lines separately and returns the largest width.
Changes From GLUT
GLUT does not include this function.
14.5 glutBitmapHeight
The "glutBitmapHeight" function returns the height in pixels of
the specified font.
Usage
int glutBitmapHeight ( void *font
) ;
font
The bitmapped font to use in calculating
the character height
Description
The "glutBitmapHeight
" function returns the height of a character in the specified bitmap font.
Because the font is bitmapped, the height is an exact integer. The fonts
are designed such that all characters have (nominally) the same height.
Changes From GLUT
GLUT does not include this function.
14.6 glutStrokeCharacter
The "glutStrokeCharacter" function renders a single stroke character
in the current window using the specified font.
Usage
void glutStrokeCharacter ( void *font,
int character ) ;
font
The stroke font to use in rendering
the character
character The ASCII
code of the character to be rendered
Description
The "glutStrokeCharacter
" function renders the given character in the specified stroke font.
Before the first call to "glutStrokeCharacter" the application program
should call the OpenGL transformation (positioning and scaling) functions
to set the position of the character in the window. The "glutStrokeCharacter
" function advances the cursor position by a call to "glTranslatef
" and so the application does not need to call the OpenGL positioning functions
again for successive characters on the same line.
Changes From GLUT
Nonexistent characters are rendered as
asterisks.
14.7 glutStrokeString
The "glutStrokeString" function renders a string of characters
in the current window using the specified stroke font.
Usage
void glutStrokeString ( void *font,
char *string ) ;
font
The stroke font to use in rendering
the character string
string String
of characters to be rendered
Description
The "glutStrokeString
" function renders the given character string in the specified stroke font.
Before calling "glutStrokeString" the application program should
call the OpenGL transformation (positioning and scaling) functions to set
the position of the string in the window. The "glutStrokeString
" function handles carriage returns. Nonexistent characters are rendered
as asterisks.
Changes From GLUT
GLUT does not include this function.
14.8 glutStrokeWidth
The "glutStrokeWidth" function returns the width in pixels of
a single character in the specified stroke font.
Usage
int glutStrokeWidth ( void *font,
int character ) ;
font
The stroke font to use in calculating
the character width
character The ASCII
code of the character
Description
The "glutStrokeWidth"
function returns the width of the given character in the specified stroke
font. Because the font is a stroke font, the width is actually a floating-point
number; the function rounds it to the nearest integer for the return value.
Changes From GLUT
Nonexistent characters return the width
of an asterisk.
14.9 glutStrokeLength
The "glutStrokeLength" function returns the width in pixels of
a string of characters in the specified stroke font.
Usage
int glutStrokeLength ( void *font,
char *string ) ;
font The stroke
font to use in calculating the character width
string String of characters
whose width is to be calculated
Description
The "glutStrokeLength
" function returns the width in pixels of the given character string in
the specified stroke font. Because the font is a stroke font, the width
of an individual character is a floating-point number. Freeglut
adds the floating-point widths and rounds the funal result to return the
integer value. Thus the return value may differ from the sum of the
character widths returned by a series of calls to "glutStrokeWidth
". The width of nonexistent characters is counted to be the width
of an asterisk.
If the string contains
one or more carriage returns, freeglut calculates the widths in pixels
of the lines separately and returns the largest width.
Changes From GLUT
GLUT does not include this function.
14.10 glutStrokeHeight
The "glutStrokeHeight" function returns the height in pixels of
the specified font.
Usage
GLfloat glutStrokeHeight ( void *font
) ;
font
The stroke font to use in calculating
the character height
Description
The "glutStrokeHeight
" function returns the height of a character in the specified stroke font.
The application programmer should note that, unlike the other freeglut
font functions, this one returns a floating-point number. The fonts
are designed such that all characters have (nominally) the same height.
Changes From GLUT
GLUT does not include this function.
15.0
Geometric Object Rendering Functions
Freeglut includes eighteen routines for generating easily-recognizable
3-d geometric objects. These routines are effectively the same ones
that are included in the GLUT library, and reflect the functionality available
in the aux toolkit described in the OpenGL Programmer's Guide
. They are included to allow programmers to create with a single
line of code a three-dimensional object which can be used to test a variety
of OpenGL functionality. None of the routines generates a display list
for the object which it draws. The functions generate normals appropriate
for lighting but, except for the teapon functions, do not generate texture
coordinates.
15.1 glutWireSphere, glutSolidSphere
The "glutWireSphere" and "glutSolidSphere" functions
draw a wireframe and solid sphere respectively.
Usage
void glutWireSphere ( GLdouble dRadius,
GLint slices, GLint stacks ) ;
void glutSolidSphere ( GLdouble dRadius,
GLint slices, GLint stacks ) ;
dRadius
The desired radius of the sphere
slices
The desired number of slices (divisions
in the longitudinal direction) in the sphere
stacks
The desired number of stacks (divisions
in the latitudinal direction) in the sphere. The number of points in
this direction, including the north and south poles, is stacks+1
Description
The "glutWireSphere" and "
glutSolidSphere" functions render a sphere centered at the origin
of the modeling coordinate system. The north and south poles of the
sphere are on the positive and negative Z-axes respectively and the prime
meridian crosses the positive X-axis.
Changes From GLUT
None that we know of.
15.2 glutWireTorus, glutSolidTorus
The "glutWireTorus" and "glutSolidTorus" functions draw
a wireframe and solid torus (donut shape) respectively.
Usage
void glutWireTorus ( GLdouble dInnerRadius,
GLdouble dOuterRadius, GLint nSides, GLint nRings ) ;
void glutSolidTorus ( GLdouble dInnerRadius,
GLdouble dOuterRadius, GLint nSides, GLint nRings ) ;
dInnerRadius
The desired inner radius of the torus,
from the origin to the circle defining the centers of the outer circles
dOuterRadius
The desired outer radius of the torus,
from the center of the outer circle to the actual surface of the torus
nSides
The desired number of segments in a
single outer circle of the torus
nRings
The desired number of outer circles
around the origin of the torus
Description
The "glutWireTorus" and "
glutSolidTorus" functions render a torus centered at the origin of
the modeling coordinate system. The torus is circularly symmetric about
the Z-axis and starts at the positive X-axis.
Changes From GLUT
None that we know of.
15.3 glutWireCone, glutSolidCone
The "glutWireCone" and "glutSolidCone" functions draw
a wireframe and solid cone respectively.
Usage
void glutWireCone ( GLdouble base,
GLdouble height, GLint slices, GLint stacks ) ;
void glutSolidCone ( GLdouble base,
GLdouble height, GLint slices, GLint stacks ) ;
base
The desired radius of the base of the
cone
height
The desired height of the cone
slices
The desired number of slices around
the base of the cone
stacks
The desired number of segments between
the base and the tip of the cone (the number of points, including the tip,
is stacks + 1)
Description
The "glutWireCone" and "
glutSolidCone" functions render a right circular cone with a base
centered at the origin and in the X-Y plane and its tip on the positive Z-axis.
The wire cone is rendered with triangular elements.
Changes From GLUT
None that we know of.
15.4 glutWireCube, glutSolidCube
The "glutWireCube" and "glutSolidCube" functions draw
a wireframe and solid cube respectively.
Usage
void glutWireCube ( GLdouble dSize
) ;
void glutSolidCube ( GLdouble dSize
) ;
dSize
The desired length of an edge of the
cube
Description
The "glutWireCube" and "
glutSolidCube" functions render a cube of the desired size, centered
at the origin. Its faces are normal to the coordinate directions.
Changes From GLUT
None that we know of.
15.5 glutWireTetrahedron, glutSolidTetrahedron
The "glutWireTetrahedron" and "glutSolidTetrahedron"
functions draw a wireframe and solid tetrahedron (four-sided Platonic solid)
respectively.
Usage
void glutWireTetrahedron ( void )
;
void glutSolidTetrahedron ( void
) ;
Description
The "glutWireTetrahedron" and
"glutSolidTetrahedron" functions render a tetrahedron whose corners
are each a distance of one from the origin. The length of each side
is 2/3 sqrt(6). One corner is on the positive X-axis and another is
in the X-Y plane with a positive Y-coordinate.
Changes From GLUT
None that we know of.
15.6 glutWireOctahedron, glutSolidOctahedron
The "glutWireOctahedron" and "glutSolidOctahedron" functions
draw a wireframe and solid octahedron (eight-sided Platonic solid) respectively.
Usage
void glutWireOctahedron ( void )
;
void glutSolidOctahedron ( void )
;
Description
The "glutWireOctahedron" and
"glutSolidOctahedron" functions render an octahedron whose corners
are each a distance of one from the origin. The length of each side
is sqrt(2). The corners are on the positive and negative coordinate
axes.
Changes From GLUT
None that we know of.
15.7 glutWireDodecahedron, glutSolidDodecahedron
The "glutWireDodecahedron" and "glutSolidDodecahedron
" functions draw a wireframe and solid dodecahedron (twelve-sided Platonic
solid) respectively.
Usage
void glutWireDodecahedron ( void
) ;
void glutSolidDodecahedron ( void
) ;
Description
The "glutWireDodecahedron" and
"glutSolidDodecahedron" functions render a dodecahedron whose corners
are each a distance of sqrt(3) from the origin. The length of each
side is sqrt(5)-1. There are twenty corners; interestingly enough,
eight of them coincide with the corners of a cube with sizes of length 2.
Changes From GLUT
None that we know of.
15.8 glutWireIcosahedron, glutSolidIcosahedron
The "glutWireIcosahedron" and "glutSolidIcosahedron"
functions draw a wireframe and solid icosahedron (twenty-sided Platonic solid)
respectively.
Usage
void glutWireIcosahedron ( void )
;
void glutSolidIcosahedron ( void
) ;
Description
The "glutWireIcosahedron" and
"glutSolidIcosahedron" functions render an icosahedron whose corners
are each a unit distance from the origin. The length of each side is
slightly greater than one. Two of the corners lie on the positive and
negative X-axes.
Changes From GLUT
None that we know of.
15.7 glutWireRhombicDodecahedron,
glutSolidRhombicDodecahedron
The "glutWireRhombicDodecahedron" and "glutSolidRhombicDodecahedron
" functions draw a wireframe and solid rhombic dodecahedron (twelve-sided
semi-regular solid) respectively.
Usage
void glutWireRhombicDodecahedron
( void ) ;
void glutSolidRhombicDodecahedron
( void ) ;
Description
The "glutWireRhombicDodecahedron
" and "glutSolidRhombicDodecahedron" functions render a rhombic
dodecahedron whose corners are at most a distance of one from the origin.
The rhombic dodecahedron has faces which are identical rhombuses (rhombi?)
but which have some vertices at which three faces meet and some vertices at
which four faces meet. The length of each side is sqrt(3)/2. Vertices
at which four faces meet are found at (0, 0, +1) and ( +sqrt(2)/2,
+sqrt(2)/2, 0).
Changes From GLUT
GLUT does not include these functions.
15.10 glutWireTeapot, glutSolidTeapot
The "glutWireTeapot" and "glutSolidTeapot" functions
draw a wireframe and solid teapot respectively.
Usage
void glutWireTeapot ( GLdouble dSize
) ;
void glutSolidTeapot ( GLdouble dSize
) ;
dSize
The desired size of the teapot
Description
The "glutWireTeapot" and "
glutSolidTeapot" functions render a teapot of the desired size, centered
at the origin. This is the famous OpenGL teapot [add reference].
Changes From GLUT
None that we know of.
16.0
Game Mode Functions
16.1 glutGameModeString
16.2 glutEnterGameMode, glutLeaveGameMode
16.3 glutGameModeGet
17.0
Video Resize Functions
17.1 glutVideoResizeGet
17.2 glutSetupVideoResizing,
glutStopVideoResizing
17.3 glutVideoResize
17.4 glutVideoPan
18.0
Color Map Functions
18.1 glutSetColor, glutGetColor
18.2 glutCopyColormap
19.0
Miscellaneous Functions
19.1 glutIgnoreKeyRepeat, glutSetKeyRepeat
19.2 glutForceJoystickFunc
19.3 glutReportErrors
20.0
Usage Notes
The following environment variables
are recognized by freeglut:
- DISPLAY - specifies a display name.
- GLUT_FPS - specifies a time interval
(in milliseconds) for reporting framerate messages to stderr. For example,
if FREEGLUT_FPS is set to 5000, every 5 seconds a message will be printed
to stderr showing the current frame rate. The frame rate is measured by counting
the number of times glutSwapBuffers() is called over the time interval.
- GLUT_ICON - specifies the icon that
goes in the upper left-hand corner of the freeglut windows
21.0
Implementation Notes
22.0
GLUT State
23.0
"freeglut.h" Header File
Application programmers who are porting their GLUT programs to freeglut may continue
to include <GL/glut.h> in their programs.
Programs which use the freeglut-specific extensions to GLUT should include
<GL/freeglut.h>. One possible arrangement is as follows:
#ifdef FREEGLUT
#include <GL/freeglut_ext.h>
#else
#include <GL/glut.h>
#endif
Compile-time freeglut version testing can be done as follows:
#ifdef FREEGLUT_VERSION_2_0
code specific to freeglut 2.0 or later here
#endif
In future releases, FREEGLUT_VERSION_2_1, FREEGLUT_VERSION_2_2, etc will
be defined. This scheme mimics OpenGL conventions.
The freeglut version can be queried at runtime by calling
glutGet(GLUT_VERSION).
The result will be X*10000+Y*100+Z where X is the major version, Y is the
minor version and Z is the patch level.
This may be used as follows:
if (glutGet(GLUT_VERSION) < 20001) {
printf("Sorry, you need freeglut version 2.0.1 or later to run this program.\n");
exit(1);
}
24.0
References
25.0
Index
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