OpenGL Toolkits FAQ (2-2005)
 I. GLUT
 II. Popular GLUT Patches
 III. OpenGL Game Development Frameworks
 IV. OpenGL Windowing Application Frameworks
 V. Upper Level OpenGL User Interface Widget Libraries
 VI. More Toolkits Information and Support
 VII. Font Rendering libraries for OpenGL
 VIII. Scripting interfaces to OpenGL


I. GLUT

 
 GLUT, or OpenGL Utility Toolkit was written by Mark Kilgard. The first version
 of the library was released back in 1994. Since then it has been ported to pretty much 
 every platform that exists. It is used in thousands of demos including the demos used in 
 the OpenGL Red Book. The current version is 3.7. Additional releases of the library are 
 not anticipated. The library is very useful in prototyping OpenGL applications and games,
 and in writing OpenGL demos. 
 For answers to common questions about GLUT functionality, make sure and read 
 the GLUT section of OpenGL.org's OpenGL Developer FAQ.
 1) Where can I find compiled GLUT libraries, source code and docs?
 a) Opengl.org's GLUT download page.
 b) Nate Robins's GLUT for Windows.
 c) FreeGlut - Opensource re-write of the popular GLUT library.
 d) GLUT 3.7.2 API Documentation.
 2) Is GLUT Open Source? 
 GLUT is not open source. Mark Kilgard maintains the the copyright. There are
 a number of newer alternatives, including FreeGlut.
 3) How do I track keyboard input using GLUT?
 The best way to do this is to track the keyboard state using 
 an array, something like this (Win32 console example code):
 // gluttest.cpp : Defines the entry point for the console application.
 //
 #include 
 #include 
 #include "glut.h"
 #pragma comment( lib, "glut32" )
 static bool keystate[256];
 void glutKeyboardUpCallback( unsigned char key, int x, int y )
 {
 printf( "keyup=%i\n", key );
 keystate[key] = false;
 }
 void glutKeyboardCallback( unsigned char key, int x, int y )
 {
 printf( "keydn=%i\n", key );
 keystate[key] = true;
 }
 void glutDisplayCallback( void )
 {
 Sleep(100);
 for ( int i=0; i <= 255; i++ ) { if ( keystate[i] == true ) printf( "ASCII key %i is pressed.\n", i ); } glutPostRedisplay(); } int main(int argc, char* argv[]) { glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutCreateWindow( "test" ); glutKeyboardFunc( glutKeyboardCallback ); glutKeyboardUpFunc( glutKeyboardUpCallback ); glutDisplayFunc( glutDisplayCallback ); glutMainLoop(); return 0; } 4) Help with glutGameMode http://www.nullterminator.net/glut.html
 glutGameModeString 
 glutGameModeString is a useful function for setting the screen resolution, 
 refresh rate, and bit depth for fullscreen applications (like games). The 
 sole parameter is a pointer to a string which specifies the screen properties 
 desired. 
 glutGameModeString( "640x480:16@60" );
 In the above example, this selects a resolution of 640x480, 16 bits per pixel 
 (bit depth), and 60Hz refresh rate. You can create your own game mode string 
 using the following sprintf statement or your own method. 
 char temp[64];
 sprintf( temp, "%dx%d:%d@%d", width, height,
 pixelDepth, refreshRate );
 
 Think of this as a request to the GLUT system. You aren't necessarily guarenteed 
 the mode you requested. 
 glutGameModeGet 
 To see what you are working with, simply use the glutGameModeGet function. 
 The single arguement specifies what you are trying to get. Here's a list 
 of possible arguements. 
 Arguement Description 
 GLUT_GAME_MODE_ACTIVE Whether game mode is active. 
 GLUT_GAME_MODE_POSSIBLE Whether game mode is possible. 
 GLUT_GAME_MODE_WIDTH The game mode screen width (ex. 640 pixels). 
 GLUT_GAME_MODE_HEIGHT The game mode screen height (ex. 480 pixels). 
 GLUT_GAME_MODE_PIXEL_DEPTH The game mode pixel depth (ex. 16bits). 
 GLUT_GAME_MODE_REFRESH_RATE The game mode screen pixel depth (ex. 60Hz). 
 GLUT_GAME_MODE_DISPLAY_CHANGED Whether game mode changed the display. 
 To determine what mode we are dealing with, the following code snippet 
 should suffice for most cases. 
 width = glutGameModeGet( GLUT_GAME_MODE_WIDTH );
 height = glutGameModeGet( GLUT_GAME_MODE_WIDTH );
 pixelDepth = glutGameModeGet( GLUT_GAME_MODE_PIXEL_DEPTH );
 refreshRate = glutGameModeGet( GLUT_GAME_MODE_REFRESH_RATE );
 glutEnterGameMode 
 Instead of worrying about a bunch of calls to the Operating System to 
 initialize a fullscreen window and create the OpenGL interface, you 
 can do it in one single call to glutEnterGameMode. It's that simple. 
 Think of it as a replacement to your usual call of glutCreateWindow. 
 Then you must setup your callbacks (display, keyboard, etc) after the 
 call to glutEnterGameMode just like an ordinary GLUT program. 
 int main(int argc, char * argv[])
 {
 // initialize GLUT
 glutInit( &argc, argv );
 // set RGBA mode with double and depth buffers
 glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
 // 640x480, 16bit pixel depth, 60Hz refresh rate
 glutGameModeString( "640x480:16@60" );
 // start fullscreen game mode
 glutEnterGameMode();
 // setup window callbacks
 glutDisplayFunc( display );
 glutKeyboardFunc( keyboard );
 glutIdleFunc( idle );
 ...
 // enter main loop
 glutMainLoop();
 return 0;
 }
 glutLeaveGameMode 
 After you are finished with the fullscreen window, you can get 
 rid of it with a call to glutLeaveGameMode somewhere where you 
 are shutting down. 


II. Popular GLUT Patches

 For answers to common questions about GLUT functionality, make sure and read 
 the GLUT section of OpenGL.org's OpenGL Developer FAQ.
 1) Fixing GLUT's "X" button close window exit() bug
 Rob Fletcher, at the University of York, has written a fix to the GLUT 
 window-close problem. He's added a callback which informs the caller 
 when a window is closed. The default action is to exit, so this is 
 backwards-compatible with existing code. But multi-window GLUT applications 
 can now handle window closes properly. 
 Editors Note: 
 Rob's patch adds a window close callback -
 
 void glutWMCloseFunc( void (*func)(void) );
 
 It also creates a re-entrant event loop that returns on exit to the calling 
 process. e.g.:
 for(;;)
 glutCheckLoop()
 Rob Fletcher's GLUT Patches.
 2) Creating a re-entrant glutMainloop.
 Steven Baker's glutMainLoopUpdate.
 Rob Fletcher's GLUT Patches.


III. OpenGL Game Development Frameworks

 Game frameworks take the hassle out of OpenGL game programming by providing
 an underlying support layer for the developer to rely on. Each framework has
 various different features and platform support. Click on the links below for 
 brief summaries of each.
 1) GLUT - See the GLUT section of this FAQ.
 2) GLFW - An OpenGL Framework.
 3) Cpw - Cross Platform Windowing for OpenGL.
 4) PLIB - The Portable Games Library.
 5) FreeGlut - Opensource re-write of the popular GLUT library.
 6) GLT - GL C++ Toolkit.
 7) Grand Unified Toolkit - a cross-platform C++ API for game development.
 8) DemoGL - execution platform for multi-media based graphical effects.
 9) SDL - cross-platform multimedia library adapted to OpenGL.


IV. OpenGL Windowing Application Frameworks

 Application frameworks take the hassle out of Window based OpenGL 
 applications by providing an underlying support layer for the developer 
 to rely on. Each framework has various different features and platform 
 support. Click on the links below for brief summaries of each.
 1) GLUT - See the GLUT section of this FAQ.
 2) Cpw - Cross Platform Windowing for OpenGL.
 3) FreeGlut - Opensource re-write of the popular GLUT library.
 4) GLT - GL C++ Toolkit.
 5) GLFW - An OpenGL Framework.
 6) SDL - cross-platform multimedia library adapted to OpenGL.


V. Upper Level OpenGL User Interface Widget Libraries

 Widget Libraries or UI Frameworks take the hassle out of displaying
 common windowing controls such as drop downs, text entry, and buttons.
 Each framework has various different features and platform support. 
 Click on the links below for brief summaries of each.
 1) MUI/PUI/GLUI 
 a) GLUI Home Page
 b) Steve Baker's MUI/PUI/GLUI Information
 2) GLOW - a C++ OpenGL Widget Library.
 3) FLTK - a C++ OpenGL Widget Library.
 4) FOX - C++ Toolkit for developing Graphical User Interfaces easily.
 5) libUFO - a C++ OpenGL Widget Library.
 6) GLOWaux - a C++ OpenGL Framework for the GLOW Library.
 7) Cpw - Cross Platform Windowing for OpenGL.
 8) GLGooey - platform-independent, small, extensible collection of user interface components.


VI. More Toolkits Information and Support

 1) Visit the www.OpenGL.org Toolkits Discussion Forum
 2) Google Directory: OpenGL Add-on Libraries
 3) The OpenGL Developer FAQ and TroubleShooting Guide
 4) The OpenGL Game Development FAQ


VII. Font Rendering in OpenGL

 A number of different libraries support various different types of font rendering
 in OpenGL. Make sure and read OpenGL.org's Survey of OpenGL Font Technology.
 1) GLUT - ANSI C, Simple Stroke and Bitmap Fonts.
 2) glFont - ANSI C, Texture Mapped Fonts.
 3) FTGL - C++, TrueType Fonts, Requires FreeType 2.0.
 4) GLTT - C++, TrueType Fonts, Requires FreeType 1.0.
 5) FNT - Part of PLIB, ANSI C.
 6) GLF
 7) Cpw - ANSI C, TrueType Fonts, Requires FreeType 2.0.


VIII. Scripting interfaces to OpenGL

 A number of different scripting engines support OpenGL. Aside from interfaces 
 for common languages such as Python there are a number of less known scripting 
 languages out there that provide unique ways of programming in OpenGL. 
 1) SharpGL - C# wrapper for OpenGL #1
 2) CFC# OpenGL Wrapper - C# wrapper for OpenGL #2
 3) CsGl - CsGL implements a wrapper for the well known C-library OpenGL allowing any 
 .NET language make use of it.
 4) LuaGL - Lua is a powerful light-weight programming language designed for extending 
 applications. 
 5) IoGL - Io is small prototype-based programming language.