The Open-Source
OpenGL Utility Toolkit
(freeglut 3.0.0)
Application Programming Interface

Version 4.0

The freeglut Programming Consortium
January, 2013

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. Contents

  1. Contents
  2. Introduction
  3. Background
    1. Design Philosophy
    2. Conventions
    3. Terminology
    4. Differences from GLUT 3.7
  4. Initialization Functions
    1. glutInit
    2. glutInitWindowPosition, glutInitWindowSize
    3. glutInitDisplayMode
    4. glutInitDisplayString
    5. glutInitErrorFunc, glutInitWarningFunc
  5. Event Processing Functions
    1. glutMainLoop
    2. glutMainLoopEvent
    3. glutLeaveMainLoop
  6. Window Functions
    1. glutCreateWindow
    2. glutCreateSubwindow
    3. glutDestroyWindow
    4. glutSetWindow, glutGetWindow
    5. glutSetWindowTitle, glutSetIconTitle
    6. glutReshapeWindow
    7. glutPositionWindow
    8. glutShowWindow, glutHideWindow, glutIconifyWindow
    9. glutPushWindow, glutPopWindow
    10. glutFullScreen, glutLeaveFullScreen, glutFullScreenToggle
  7. Display Functions
    1. glutPostRedisplay
    2. glutPostWindowRedisplay
    3. glutSwapBuffers
  8. Mouse Cursor Functions
    1. glutSetCursor
    2. glutWarpPointer
  9. Overlay Functions
    1. glutEstablishOverlay
    2. glutRemoveOverlay
    3. glutUseLayer
    4. glutPostOverlayRedisplay
    5. glutPostWindowOverlayRedisplay
    6. glutShowOverlay, glutHideOverlay
  10. Menu Functions
    1. glutCreateMenu
    2. glutDestroyMenu
    3. glutGetMenu, glutSetMenu
    4. glutAddMenuEntry
    5. glutAddSubMenu
    6. glutChangeToMenuEntry
    7. glutChangeToSubMenu
    8. glutSetMenuFont
    9. glutRemoveMenuItem
    10. glutAttachMenu, glutDetachMenu
    11. glutMenuDestroyFunc
  11. Global Callback Registration Functions
    1. glutTimerFunc
    2. glutIdleFunc
    3. glutMenuStatusFunc
    4. glutMenuStateFunc
  12. Window-Specific Callback Registration Functions
    1. glutDisplayFunc
    2. glutOverlayDisplayFunc
    3. glutReshapeFunc
    4. glutPositionFunc
    5. glutCloseFunc
    6. glutKeyboardFunc
    7. glutSpecialFunc
    8. glutKeyboardUpFunc
    9. glutSpecialUpFunc
    10. glutMotionFunc, glutPassiveMotionFunc
    11. glutMouseFunc
    12. glutMouseWheelFunc
    13. glutEntryFunc
    14. glutJoystickFunc
    15. glutSpaceballMotionFunc
    16. glutSpaceballRotateFunc
    17. glutSpaceballButtonFunc
    18. glutButtonBoxFunc
    19. glutDialsFunc
    20. glutTabletMotionFunc
    21. glutTabletButtonFunc
    22. glutVisibilityFunc, glutWindowStatusFunc
  13. State Setting and Retrieval Functions
    1. glutSetOption
    2. glutGet
    3. glutDeviceGet
    4. glutGetModifiers
    5. glutLayerGet
    6. glutExtensionSupported
    7. glutGetProcAddress
  14. Font Rendering Functions
    1. glutBitmapCharacter
    2. glutBitmapString
    3. glutBitmapWidth
    4. glutBitmapLength
    5. glutBitmapHeight
    6. glutStrokeCharacter
    7. glutStrokeString
    8. glutStrokeWidth
    9. glutStrokeWidthf
    10. glutStrokeLength
    11. glutStrokeLengthf
    12. glutStrokeHeight
  15. Geometric Object Rendering Functions
    1. glutWireSphere, glutSolidSphere
    2. glutWireTorus, glutSolidTorus
    3. glutWireCone, glutSolidCone
    4. glutWireCube, glutSolidCube
    5. glutWireTetrahedron, glutSolidTetrahedron
    6. glutWireOctahedron, glutSolidOctahedron
    7. glutWireDodecahedron, glutSolidDodecahedron
    8. glutWireIcosahedron, glutSolidIcosahedron
    9. glutWireRhombicDodecahedron, glutSolidRhombicDodecahedron
    10. glutWireTeapot, glutSolidTeapot, glutWireTeacup, glutSolidTeacup, glutWireTeaspoon, glutSolidTeaspoon
    11. glutSetVertexAttribCoord3, glutSetVertexAttribNormal, glutSetVertexAttribTexCoord2
  16. Game Mode Functions
    1. glutGameModeString
    2. glutEnterGameMode, glutLeaveGameMode
    3. glutGameModeGet
  17. Video Resize Functions
    1. glutVideoResizeGet
    2. glutSetupVideoResizing, glutStopVideoResizing
    3. glutVideoResize
    4. glutVideoPan
  18. Color Map Functions
    1. glutSetColor, glutGetColor
    2. glutCopyColormap
  19. MultiTouch Functions
    1. glutMultiEntryFunc ← id, GLUT_ENTERED|GLUT_LEFT
    2. glutMultiButtonFunc ← id, x, y, button, GLUT_DOWN|GLUT_UP
    3. glutMultiMotionFunc ← id, x, y
    4. glutMultiPassiveFunc ← id, x, y
  20. Mobile functions
    1. glutInitContextFunc ← void
    2. glutAppStatusFunc ← event
  21. Miscellaneous Functions
    1. glutSetKeyRepeat, glutIgnoreKeyRepeat
    2. glutForceJoystickFunc
    3. glutReportErrors
  22. Usage Notes
    1. Implementation Notes
    2. GLUT State
    3. "freeglut.h" Header File
    4. References
    5. Index

2. Introduction

3. 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

In developing the freeglut library, we have taken careful steps to ensure consistency in function operation across the board, in such a manner as to maintain compatibility with GLUT's behavior whenever possible. In this section some of the important conventions of FreeGLUT, and their compatibility with GLUT, are made explicit.

3.2.1 Window placement and size

There is considerable confusion about the "right thing to do" concerning window size and position. GLUT itself is not consistent between Windows and UNIX/X11; since platform independence is a virtue for freeglut, we decided to break with GLUT's behaviour.
Under UNIX/X11, it is apparently not possible to get the window border sizes in order to subtract them off the window's initial position until some time after the window has been created. Therefore we decided on the following behavior, both under Windows and under UNIX/X11:

3.2.2 User-data callbacks

GLUT was created as a tool to help teach OpenGL programming. To simplify development, callbacks were used for handling display, input, and other events. But at the time it was developed, the purpose, or for some other unknown reason, the callbacks lacked any user-provided data argument. This has caused considerable difficulties for any significantly advanced usage of GLUT, and now freeglut. This has prevented any attempt to wrap freeglut in a C++ wrapper, make per-window, per-callback data structure, and potentially made it undesirable to modern C developers who tend to be well versed in "don't use globals". To combat these complaints and issues, many callbacks (with some deprecated callbacks excluded) support user-data callbacks provided through additional functions provided in freeglut. All callbacks that support user-data callbacks are marked as such.

The general rule to follow is to take the freeglut callback function and append "Ucall" to the end of the function, add an additional void* argument to the end of the argument list of both the freeglut function and the callback function. This will pass the user-data to the callback when it's invoked.

Examples

void glutPositionFunc ( void (* func)( int x, int y ) );
void glutPositionFuncUcall ( void (* func)( int x, int y, void* user_data ), void* user_data );

void glutKeyboardUpFunc ( void (* func)( unsigned char key, int x, int y ) );
void glutKeyboardUpFuncUcall ( void (* func)( unsigned char key, int x, int y, void* user_data ), void* user_data );

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 Fullscreen windows

Function to leave fullscreen window mode, glutLeaveFullScreen, or to toggle between fullscreen and normal window mode, glutFullScreenToggle, have been added.

3.4.4 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), a window status callback (also with one argument), and a window position callback. Unsupported callbacks are the two Tablet callbacks. If the user has a need for an unsupported callback he should contact the freeglut development team.

3.4.5 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.

3.4.6 Geometry Rendering

Two functions have been added to render a wireframe and a solid rhombic dodecahedron. Furthermore, solid and wireframe versions of the original teacup and teaspoon that accompanied the famous Newell teapot. As these geometry functions are often used for teaching purposes, glutSetOption(GLUT_GEOMETRY_VISUALIZE_NORMALS,true/false) can now be used to visualize the normal vectors for each vertex. Lastly, to support drawing these objects with shaders, three functions have been added with which users can provide the addresses of the Coordinate, Normal and Texture Coordinate vertex attribs: glutSetVertexAttribCoord3, glutSetVertexAttribNormal, and glutSetVertexAttribTexCoord2. Texture coordinates are only generated for the teaset.

3.4.7 Extension Function Queries

glutGetProcAddress is a wrapper for the glXGetProcAddressARB and wglGetProcAddress functions.

4. 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, but 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 both Linux and Windows, you specify the coordinates of the upper left-hand corner of the window's decorations. Also for both operating systems, the size of the window is the size of the usable interior.
With glutGet information can be acquired about the current window's size, position and decorations. Note however that according to FreeGLUT's conventions, the information returned about the window coordinates does not correspond to the coordinates used when setting window position. In addition, GLUT only accepts positive window coordinates, and ignores all negative window coordinates. But if GLUT_ALLOW_NEGATIVE_WINDOW_POSITION is enabled, then negative window coordinates can be used. This is useful for multi-montitor setups where the second monitor may be in the negative desktop space of the primary monitor, as now the window can be placed on the additional monitors. Furthermore, this flag also determines how negative coordinates and sizes are interpreted for subwindows.

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.

If GLUT_ALLOW_NEGATIVE_WINDOW_POSITION is enabled, glutInitWindowPosition will accept negative window coordinates.

4.3 glutInitDisplayMode

4.4 glutInitDisplayString

Changes From GLUT

glutInitDisplayString support is limited: any of the tokens recognized by GLUT are also recognized by FreeGLUT, but any statements with comparators cannot (yet: do help develop this!) be handled. Any spec (comparator and value) after the token is ignored. However, many of these values can be set with glutSetOption for now...

4.5 glutInitErrorFunc, glutInitWarningFunc

The glutInitErrorFunc and glutInitWarningFunc functions specify callbacks that will be called upon warnings and errors issued from within FreeGLUT so that the user can deal with these. Useful for rerouting to another output sink (e.g., logging) and also to avoid exit(1) being called upon error. As with other glutInit* functions, these can be set before glutInit is called, so any output from the library can be handled by the user.

Usage

void glutInitErrorFunc   ( void (* callback)( const char *fmt, va_list ap) );
void glutInitWarningFunc ( void (* callback)( const char *fmt, va_list ap) );

These functions have user-data callback functions.

Description

The users callback is passed a format string and a variable argument list that can be passed to functions such as printf.
Note that there are the preprocessor definitions FREEGLUT_PRINT_ERRORS and FREEGLUT_PRINT_WARNINGS, which affect FreeGLUT's warning and error behavior when no user callback is defined. If defined at library (not client app!) compile time--by default it is, warnings and errors are printed to stderr. If not defined, warnings and errors are muted (not printed to stderr), though errors still trigger deinitialization and exit. Whether FREEGLUT_PRINT_ERRORS and FREEGLUT_PRINT_WARNINGS is defined does not affect whether the client callback is called, it only affects whether warnings and errors are printed to stderr when no callback is defined.

Changes From GLUT

GLUT does not provide these functions.

5. 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_GLUTMAINLOOP_RETURNS or 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. Window Functions

6.1 glutCreateWindow

6.2 glutCreateSubwindow

The glutCreateSubwindow function creates a subwindow of an existing window.

Usage

int glutCreateSubwindow(int window, int x, int y, int width, int height);

Description

Creates a subwindow of window that is at location x and y relative to the window's upper-left corner, and is of the specified width and height. The newly created window ID is returned by glutCreateSubwindow. By default, the position coordinates will only allow windows within the bounds of the parent. Negative coordinates be treated as coordinates from the opposite edge for a given axis. In addition, the width of the window will be taken into account. For example, if the parent window is 100 pixels wide, and the x is 10, and width is 20, the subwindow will be located at x = 10. If x is -10, then the subwindow will be located at 70 (parent - abs(pos) - dim). If the width or height are negative, then the dimension is taken as a subtraction of the parent dimension. For example, if the parent window is 100 pixels wide, and the x is 10, and width is 20, the subwindow will have a size of 20. If width is -20, then the subwindow will have a width of 70 (parent - pos - abs(dim)).

If GLUT_ALLOW_NEGATIVE_WINDOW_POSITION is enabled, the window behavior differs. Negative window coordinates are now accepted and may result in windows outside of the viewing area, depending on the platform of operation. Negative width and height are still used as a subtraction of the parent window dimension, but they do not take x or y into account. For example, if the parent window is 100 pixels wide, and the x is 10, and width is 20, the subwindow will be located at x = 10. If x is -10, then the subwindow will be located at x = -10. If the parent window is 100 pixels wide, and the x is 10, and width is 20, the subwindow will have a size of 20. If width is -20, then the subwindow will have a width of 80 (parent - abs(dim)).

Changes From GLUT

GLUT does not support negative x or y. Nor does it have GLUT_ALLOW_NEGATIVE_WINDOW_POSITION which changes the the functionality of glutCreateSubwindow.

6.3 glutDestroyWindow

6.4 glutSetWindow, glutGetWindow

6.5 glutSetWindowTitle, glutSetIconTitle

The glutSetWindowTitle, glutSetIconTitle set the window title for when the window is in a visible state and when it is in an iconified state respectively.

Usage

glutSetWindowTitle(const char* title);
glutSetIconTitle(const char* title);

Description

Normally a window system displays a title for every top-level window in the system. The initial title is set when you call glutCreateWindow(). By means of the glutSetWindowTitle function you can set the titles for your top-level FreeGLUT windows. If you just want one title for the window over the window's entire life, you should set it when you open the window with glutCreateWindow().
glutSetIconTitle sets the title to be displayed for the window when it is in iconified (minimized) state.

Changes From GLUT

glutSetIconTitle does nothing in GLUT on Windows, but is emulated on Windows by FreeGLUT.

6.6 glutReshapeWindow

6.7 glutPositionWindow

6.8 glutShowWindow, glutHideWindow, glutIconifyWindow

6.9 glutPushWindow, glutPopWindow

6.10 glutFullScreen, glutLeaveFullScreen, glutFullScreenToggle

The glutFullScreen, glutLeaveFullScreen and glutFullScreenToggle functions are used to transition the current window between fullscreen and normal mode.

Usage

void glutFullScreen ( void );
void glutLeaveFullScreen ( void );
void glutFullScreenToggle ( void );

Description

The glutFullScreen function causes the current window to enter fullscreen mode, glutLeaveFullScreen to go back to the window size and position as it was before entering fullscreen mode, and glutFullScreenToggle toggles between fullscreen and normal mode.
In multi-monitor setups on Windows 2000 and newer, the window will become fullscreen on the monitor that it overlaps the most.
Calls to these functions are ignored for gamemode and child windows.
Use glutGet(GLUT_FULL_SCREEN) to query fullscreen state of current window.

Changes From GLUT

GLUT does not include the glutLeaveFullScreen and glutFullScreenToggle functions.

7. Display Functions

7.1 glutPostRedisplay

7.2 glutPostWindowRedisplay

7.3 glutSwapBuffers

8. Mouse Cursor Functions

8.1 glutSetCursor

8.2 glutWarpPointer

9. 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. Menu Functions

10.1 glutCreateMenu

Has user-data callback function.

10.2 glutDestroyMenu

10.3 glutGetMenu, glutSetMenu

10.4 glutAddMenuEntry

10.5 glutAddSubMenu

10.6 glutChangeToMenuEntry

10.7 glutChangeToSubMenu

10.8 glutSetMenuFont

glutSetMenuFont sets the (bitmap) font to be used for drawing the specified menu.

Usage

void glutSetMenuFont( int menuID, void* fontID );

Description

Only bitmap fonts (GLUT_BITMAP_xxx, see here for a list) can be used as menu fonts. A warning is issued and the request is ignored if the supplied font is a stroke font, or an unknown font.

Changes From GLUT

GLUT does not provide this function.

10.9 glutRemoveMenuItem

10.10 glutAttachMenu, glutDetachMenu

10.11 glutMenuDestroyFunc

Has user-data callback function.

11. Global Callback Registration Functions

11.1 glutTimerFunc

Has user-data callback function.

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

Has user-data 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. Note that no actual drawing to the framebuffer should be done from the idle callback, this is not supported. While it might work on some platforms, it will not on others or might stop working in the future. Drawing should be done in the glutDisplayFunc 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.

11.3 glutMenuStatusFunc

Has user-data callback function.

11.4 glutMenuStateFunc

12. Window-Specific Callback Registration Functions

12.1 glutDisplayFunc

Has user-data callback function.

12.2 glutOverlayDisplayFunc

Has user-data callback function.

12.3 glutReshapeFunc

Has user-data callback function.

12.4 glutPositionFunc

The glutPositionFunc function sets the window's position callback. Freeglut calls the position callback when the window is repositioned/moved programatically or by the user.

Usage

void glutPositionFunc ( void (* func)( int x, int y) );

Has user-data callback function.

Description

When FreeGLUT calls this callback, it provides the new position on the screen of the top-left of the non-client area, that is, the same coordinates used by glutInitPosition and glutPositionWindow. To get the position on the screen of the top-left of the client area, use glutGet(GLUT_WINDOW_X) and glutGet(GLUT_WINDOW_Y). See FreeGLUT's conventions for more information.

Changes From GLUT

This function is not implemented in GLUT.

12.5 glutCloseFunc

The glutCloseFunc function sets the window's close callback. Freeglut calls the close callback when the window is about to be destroyed.

Usage

void glutCloseFunc ( void (*func) ( void ) );

func The window's new closure callback function

Has user-data callback function.

Description

The glutCloseFunc function specifies the function that freeglut will call to notify the application that a window is about to be closed, either because it is requested using glutDestroyWindow, because the user clicked on the "x" in the window header (for top-level windows only), or due to a pending closure of a subwindow's parent window. In the first case, the closure callback is not invoked from the glutDestroyWindow call, but at a later time point.
Freeglut sets the current window to the window which is about to be closed when the callback is invoked. The window can thus be retrieved in the callback using glutGetWindow.
Users looking to prevent FreeGLUT from exiting when a window is closed, should look into using glutSetOption to set GLUT_ACTION_ON_WINDOW_CLOSE. Some settings will prevent the application from exiting when a window is closed.
Please note that glutWMCloseFunc, a deprecated function, is an alias to glutCloseFunc.

Changes From GLUT

This function is not implemented in GLUT.

12.6 glutKeyboardFunc

Has user-data callback function.

12.7 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

Has user-data callback function.

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:

Changes From GLUT

None.

12.8 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

Has user-data callback function.

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.

12.9 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

Has user-data callback function.

Description

The glutSpecialUpFuncfunction 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:

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.

12.10 glutMotionFunc, glutPassiveMotionFunc

Both functions have user-data callback functions.

12.11 glutMouseFunc

Has user-data callback function.

12.12 glutMouseWheelFunc

The glutMouseWheelFunc function sets the window's mouse wheel callback. Freeglut calls the mouse wheel callback when the user spins the mouse wheel.

Usage

void glutMouseWheelFunc ( void( *callback )( int wheel, int direction, int x, int y ));

Has user-data callback function.

Description

If the mouse wheel is spun over your (sub)window, FreeGLUT will report this via the MouseWheel callback. wheel is the wheel number, direction is +/- 1, and x and y are the mouse coordinates.

If you do not register a wheel callback, wheel events will be reported as mouse buttons.

Changes From GLUT

This function is not implemented in GLUT.

12.13 glutEntryFunc

Has user-data callback function.

12.14 glutJoystickFunc

Has user-data callback function.

12.15 glutSpaceballMotionFunc

The glutSpaceballMotionFunc function is implemented in freeglut on X11 only. On other platforms, function stubs are provided so that GLUT-based programs can compile and link against freeglut without modification.

Usage

void glutSpaceballMotionFunc ( void (* callback)( int x, int y, int z ) );

Has user-data callback function.

Description

TODO

12.16 glutSpaceballRotateFunc

The glutSpaceballRotateFunc function is implemented in freeglut on X11 only. On other platforms, function stubs are provided so that GLUT-based programs can compile and link against freeglut without modification.

Usage

void glutSpaceballRotateFunc ( void (* callback)( int x, int y, int z ) );

Has user-data callback function.

Description

TODO

12.17 glutSpaceballButtonFunc

The glutSpaceballButtonFunc function is implemented in freeglut on X11 only. On other platforms, function stubs are provided so that GLUT-based programs can compile and link against freeglut without modification.

Usage

void glutSpaceballButtonFunc ( void (* callback)( int button, int updown ) );

Has user-data callback function.

Description

TODO

12.18 glutButtonBoxFunc

The glutDialsFunc function sets the global dials&buttons box callback. Freeglut calls the callback when there is input from the box buttons.

Usage

void glutButtonBoxFunc ( void (* callback)( int button, int updown ) );

Has user-data callback function.

Description

The Dials&Buttons box is an ancient device presenting several pushable or rotatable buttons, sending the events to the computer via serial I/O.
See http://www.reputable.com/sgipix/sgi-dialnbutton1.jpg [1] for instance.

12.19 glutDialsFunc

The glutDialsFunc function sets the global dials&buttons box callback. Freeglut calls the callback when there is input from the box dials.

Usage

void glutDialsFunc ( void (* callback)( int dial, int value ) );

Has user-data callback function.

Description

The Dials&Buttons box is an ancient device presenting several pushable or rotatable buttons, sending the events to the computer via serial I/O.
See http://www.reputable.com/sgipix/sgi-dialnbutton1.jpg [1] for instance.

12.20 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 ) );

Has user-data callback function.

Description

The glutTabletMotionFunc function is not implemented in freeglut.

Changes From GLUT

GLUT implements this function.

12.21 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 ) );

Has user-data callback function.

Description

The glutTabletButtonFunc function is not implemented in freeglut.

Changes From GLUT

GLUT implements this function.

12.22 glutVisibilityFunc, glutWindowStatusFunc

The glutVisibilityFunc and the glutWindowStatusFunc functions set the window's visibility and windowStatus callbacks for the current window. Setting one overwrites the other. Freeglut calls these callbacks when the visibility status of a window changes.

Usage

void glutVisibilityFunc ( void( *callback )( int state ));
void glutWindowStatusFunc ( void( *callback )( int state ));

Both functions have user-data callback functions.

Description

glutVisibilityFunc is deprecated and superseded by the more informative glutWindowStatusFunc.
For glutWindowStatusFunc, the state callback parameter is one of GLUT_HIDDEN, GLUT_FULLY_RETAINED, GLUT_PARTIALLY_RETAINED, or GLUT_FULLY_COVERED depending on the current window status of the window. GLUT_HIDDEN means that the window is not shown (often meaning that the window is iconified). GLUT_FULLY_RETAINED means that the window is fully retained (no pixels belonging to the window are covered by other windows). GLUT_PARTIALLY_RETAINED means that the window is partially retained (some but not all pixels belonging to the window are covered by other windows). GLUT_FULLY_COVERED means the window is shown but no part of the window is visible, i.e., until the window's status 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.
GLUT applications are encouraged to disable rendering and/or animation when windows have a status of either GLUT_HIDDEN or GLUT_FULLY_COVERED.
If the window status callback for a window is disabled and later re-enabled, the window status of the window is undefined; any change in window window status will be reported, that is if you disable a window status callback and re-enable the callback, you are guaranteed the next window status change will be reported.
Setting the window status callback for a window disables the visibility callback set for the window (and vice versa). The visibility callback is set with glutVisibilityFunc, and its 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.
Not all window managers support such finegrained callback messages or can even ensure basic correctness. On Windows, there are no notifications if the visibility status of a window changes and FreeGLUT might be in visible state even if the window is fully obscured by other windows.

Changes From GLUT

None.

13. State Setting and Retrieval Functions

13.1 glutSetOption

Allows you to set some general state/option variables.

Usage

void glutSetOption ( GLenum eWhat, int value );

Description

Stores the value into a state variable named by eWhat.

The following state variables can be set:

Changes From GLUT

This function is not implemented in GLUT.

13.2 glutGet

The following state variables may be queried with glutGet. The returned value is an integer.

example:
int windowLeft = glutGet(GLUT_WINDOW_X);

These queries are with respect to the current window:

These queries do not depend on the current window.

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. 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:

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:

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 );

fontThe stroke font to use in rendering the character
characterThe 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 model units of a single character in the specified stroke font, rounded to an int.

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 glutStrokeWidthf

The glutStrokeWidthf function returns the width in model units of a single character in the specified stroke font.

Usage

GLfloat glutStrokeWidthf ( void *font, int character );

font The stroke font to use in calculating the character width
character The ASCII code of the character

Description

The glutStrokeWidthf function returns the width of the given character in the specified stroke font. Function was included in an unreleased GLUT 3.8.

Changes From GLUT

Nonexistent characters return the width of an asterisk.

14.10 glutStrokeLength

The glutStrokeLength function returns the width in model units of a string of characters in the specified stroke font, rounded to an int.

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 model units 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 final 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.

14.11 glutStrokeLengthf

The glutStrokeLengthf function returns the width in model units of a string of characters in the specified stroke font.

Usage

GLfloat glutStrokeLengthf ( 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 glutStrokeLengthf function returns the width in model units of the given character string in the specified stroke font. The return value is equal to the sum of the character widths returned by a series of calls to glutStrokeWidthf. Function was included in an unreleased GLUT 3.8. 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.

14.12 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. Geometric Object Rendering Functions

Freeglut includes twenty two 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 teapot functions, do not generate texture coordinates. Do note that depth testing (GL_LESS) should be enabled for the correct drawing of the nonconvex objects, i.e., the glutTorus, glutSierpinskiSponge, glutTeapot, glutTeacup and glutTeaspoon.
Also see the GLUT_GEOMETRY_VISUALIZE_NORMALS option that can be set with glutSetOption. Lastly, see glutSetVertexAttribCoord3, glutSetVertexAttribNormal, and glutSetVertexAttribTexCoord2 if you wish to use these objects with shaders.

15.1 glutWireSphere, glutSolidSphere

The glutWireSphere and glutSolidSphere functions draw a wireframe and solid sphere respectively.

Definition

void glutWireSphere (double dRadius, GLint slices, GLint stacks);
void glutSolidSphere(double dRadius, GLint slices, GLint stacks);

Arguments

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.

Definition

void glutWireTorus (double dInnerRadius, double dOuterRadius, GLint nSides, GLint nRings);
void glutSolidTorus(double dInnerRadius, double dOuterRadius, GLint nSides, GLint nRings);

Arguments

dInnerRadius  The radius of the tube.

dOuterRadius  The distance from the center of the Torus to the center of the tube.

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 glutWireCylinder, glutSolidCylinder

The glutWireCylinder and glutSolidCylinder functions draw a wireframe and solid cone respectively.

Definition

void glutWireCylinder (double base, double height, GLint slices, GLint stacks);
void glutSolidCylinder(double base, double height, GLint slices, GLint stacks);

Arguments

radius  The desired radius of the cylinder

height  The desired height of the cylinder

slices  The desired number of slices around the cylinder

stacks  The desired number of segments between the base and the top of the cylinder (the number of points, including the tip, is stacks + 1)

15.4 glutWireCone, glutSolidCone

The glutWireCone and glutSolidCone functions draw a wireframe and solid cone respectively.

Definition

void glutWireCone (double base, double height, GLint slices, GLint stacks);
void glutSolidCone(double base, double height, GLint slices, GLint stacks);

Arguments

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.

15.5 glutWireCube, glutSolidCube

The glutWireCube and glutSolidCube functions draw a wireframe and solid cube respectively.

Definition

void glutWireCube (double dSize);
void glutSolidCube(double dSize);

Arguments

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.

15.6 glutWireTetrahedron, glutSolidTetrahedron

The glutWireTetrahedron and glutSolidTetrahedron functions draw a wireframe and solid tetrahedron (four-sided Platonic solid) respectively.

Definition

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.

15.7 glutWireOctahedron, glutSolidOctahedron

The glutWireOctahedron and glutSolidOctahedron functions draw a wireframe and solid octahedron (eight-sided Platonic solid) respectively.

Definition

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.

15.8 glutWireDodecahedron, glutSolidDodecahedron

The glutWireDodecahedron and glutSolidDodecahedron functions draw a wireframe and solid dodecahedron (twelve-sided Platonic solid) respectively.

Definition

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.

15.9 glutWireIcosahedron, glutSolidIcosahedron

The glutWireIcosahedron and glutSolidIcosahedron functions draw a wireframe and solid icosahedron (twenty-sided Platonic solid) respectively.

Definition

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.

15.10 glutWireRhombicDodecahedron, glutSolidRhombicDodecahedron

The glutWireRhombicDodecahedron and glutSolidRhombicDodecahedron functions draw a wireframe and solid rhombic dodecahedron (twelve-sided semi-regular solid) respectively.

Definition

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.

15.11 glutWireTeapot, glutSolidTeapot, glutWireTeacup, glutSolidTeacup, glutWireTeaspoon, glutSolidTeaspoon

The glutWireTeapot and glutSolidTeapot functions draw a wireframe and solid teapot respectively, the glutWireTeacup and glutSolidTeacup functions a wireframe and solid teacup, and the glutWireTeaspoon and glutSolidTeaspoon functions a wireframe and solid teaspoon.

Definition

void glutWireTeapot   (double dSize);
void glutSolidTeapot  (double dSize);
void glutWireTeacup   (double dSize);
void glutSolidTeacup  (double dSize);
void glutWireTeaspoon (double dSize);
void glutSolidTeaspoon(double dSize);

Arguments

dSize  The desired size of the teapot, teacup and teaspoon - relative to a "standard" size

Description

The glutWireTeapot and glutSolidTeapot functions render a teapot of the desired size, centered at the origin. This is the famous teapot created by Martin Newell. The other functions render the teacup and teaspoon he used in the table scene figure in his PhD thesis. Vertex data retrieved from: ftp://ftp.funet.fi/pub/sci/graphics/packages/objects/teasetorig.gz.

Bugs

OpenGL's default glFrontFace state assumes that front facing polygons (for the purpose of face culling) have vertices that wind counter clockwise when projected into window space. This teapot, teacup and teaspoon are rendered with their front facing polygon vertices winding clockwise. For OpenGL's default back face culling to work, you should use:

  glFrontFace(GL_CW);
  glutSolidTeapot(size);
  glFrontFace(GL_CCW);

This bug reflect issues in the original teaset's vertex data (and is thus present in GLUT too).

Changes From GLUT

GLUT only has the teapot and misses the rest of the teaset.

15.12 glutSetVertexAttribCoord3, glutSetVertexAttribNormal, glutSetVertexAttribTexCoord2

To draw shapes with shaders (OpenGL 2 and later), one need to upload vertices and associated normal vectors and texture coordinates to vertex attributes of your shaders. Use these functions to set the indices (addresses) of the vertex attributes in your currently active shaders before calling the above geometry functions, and FreeGLUT will upload the object geometry there. Texture coordinates are only generated for the teapot, teacup and teaspoon.

Definition

void glutSetVertexAttribCoord3   (GLint attrib);
void glutSetVertexAttribNormal   (GLint attrib);
void glutSetVertexAttribTexCoord2(GLint attrib);

Arguments

attrib  The index (address) of the vertex attribute

Changes From GLUT

GLUT does not include these functions.

16. Game Mode Functions

16.1 glutGameModeString

Specify the display mode that should be entered when GameMode is entered. Default is the current display mode of the monitor on which the GameMode screen will be opened.

Usage
A string is passed to this function that specifies a combination of resolution, pixel depth (ignored on Linux) and refresh rate. Valid formats are:

Where W, H, D and R are placeholders for horizontal resolution, vertical resolution, pixel depth and refresh rate respectively, as integers. Note the "x", ":" and "@" characters.

16.2 glutEnterGameMode, glutLeaveGameMode

Attempt to change to the requested display mode and open the GameMode window, or close the GameMode window and return to the original display mode. For multi-monitor display setups, freeglut can be told on which monitor the gamemode window should be opened by providing the -display command line option to glutInit.

16.3 glutGameModeGet

The following state variables may be queried with glutGet. The returned value is an integer.

example:
int windowLeft = glutGet(GLUT_WINDOW_X);

These queries return information about the current display mode if in GameMode, or about the requested display mode before entering GameMode:

17. Video Resize Functions

These functions are not implemented in freeglut.

17.1 glutVideoResizeGet

17.2 glutSetupVideoResizing, glutStopVideoResizing

17.3 glutVideoResize

17.4 glutVideoPan

18. Color Map Functions

18.1 glutSetColor, glutGetColor

18.2 glutCopyColormap

19. MultiTouch Functions

MultiTouch callbacks are used to handle environments with multiple inputs, such as a multi-touch screen, multi-touch touchpad, or multiple mouses.

19.1 glutMultiEntryFunc ← id, GLUT_ENTERED|GLUT_LEFT

19.2 glutMultiButtonFunc ← id, x, y, button, GLUT_DOWN|GLUT_UP

19.3 glutMultiMotionFunc ← id, x, y

19.4 glutMultiPassiveFunc ← id, x, y

These functions work like their non-multi variants, with an additional 'deviceid' parameter describing the current input device (mouse or finger).
Exception: in MultiButtonFunc, the order of callback parameters is different (x,y,button,state instead of button,state,x,y).
Currently, under X11, the non-multi callback variants are also called on X11 for each event.
Currently, under windows, the first (oldest) touch point also controls the mouse cursor, which triggers the non-multi callbacks as usual.
All these functions have user-data callback functions.
Limitation: currently on the cursor id is provided. It may be desirable to get the device id as well in the following situations:

Since this extra support comes at the cost of extra complexity, we're considering whether/how to implement it.

20. Mobile Functions

These new callbacks were added:

Supported mobile platforms

21. Miscellaneous Functions

21.1 glutSetKeyRepeat, glutIgnoreKeyRepeat

The glutSetKeyRepeat and glutIgnoreKeyRepeat functions set whether repeated key presses (generated by keeping a key depressed) are passed on to the keyboard callbacks. glutSetKeyRepeat allows to globally switch off key repeat, while glutIgnoreKeyRepeat offers control over this behavior on a per-window basis.

Definition

void glutSetKeyRepeat   (int repeatMode);
void glutIgnoreKeyRepeat(int ignore);

Arguments

glutSetKeyRepeat's repeatMode   GLUT_KEY_REPEAT_OFF to globally switch key repeat off, or GLUT_KEY_REPEAT_ON and GLUT_KEY_REPEAT_DEFAULT to globally switch key repeat on.
glutIgnoreKeyRepeat's ignore    if non-zero, key repeat is switched off for the current window.

Notes

If key repeat is globally switched off through glutSetKeyRepeat, it cannot be reenabled on a per-window basis with glutIgnoreKeyRepeat. If you want per-window control of key repeat, set glutSetKeyRepeat to GLUT_KEY_REPEAT_ON and use glutIgnoreKeyRepeat(GL_TRUE) to switch off key repeat for the windows for which you don't want it.

Changes From GLUT

Nate Robbins' port of GLUT to win32 did not implement glutSetKeyRepeat, but FreeGLUT's behavior should conform on all platforms to GLUT's behavior on X11.

21.2 glutForceJoystickFunc

21.3 glutReportErrors

22. Usage Notes

The following environment variables are recognized by freeglut:

Furthermore, on windows, there is a resource file identifier GLUT_ICON that you can specify for your executable file. It specifies the icon that goes in the upper left-hand corner of the freeglut windows. Your application's resource file should contain the line:
GLUT_ICON ICON DISCARDABLE "icon.ico"
where icon.ico is the filename of your icon. The One demo includes such an icon as an example.

21.1 Implementation Notes

21.2 GLUT State

21.3 "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.h>
#else
#include <GL/glut.h>
#endif

It was initially planned to define FREEGLUT_VERSION_2_0, FREEGLUT_VERSION_2_1, FREEGLUT_VERSION_2_2, etc., but this was only done for FREEGLUT_VERSION_2_0. This constant still exist in current FreeGLUT releases but is deprecated.

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);
}

21.4 References

21.5 Index