Editing OpenGL Utility Toolkit (section)

== Limitations ==
Some of GLUT's original design decisions made it hard for programmers to perform desired tasks. This led many to create non-canon patches and extensions to GLUT.[http://www.mathies.com/glfaq/GLToolkitFAQ.html#II] Some [[free software]] or [[Open-source software|open source]] reimplementations also include fixes.

Some of the more notable limitations of the original GLUT library include:
* The library requires programmers to call <code>glutMainLoop()</code>, a function which never returns. This makes it hard for programmers to integrate GLUT into a program or library which wishes to have control of its own event loop. A common patch to fix this is to introduce a new function, called <code>glutCheckLoop()</code> (macOS) or <code>glutMainLoopEvent()</code> (FreeGLUT/OpenGLUT), which runs only a single iteration of the GLUT event loop. Another common workaround is to run GLUT's event loop in a separate [[thread (computing)|thread]], although this may vary by operating system, and also may introduce [[synchronization (computer science)|synchronization]] issues or other problems: for example, the macOS GLUT implementation requires that <code>glutMainLoop()</code> be run in the main thread.
* The fact that <code>glutMainLoop()</code> never returns also means that a GLUT program cannot exit the event loop. [[FreeGLUT]] fixes this by introducing a new function, <code>glutLeaveMainLoop()</code>.
* The library terminates the process when the window is closed; for some applications this may not be desired. Thus, many implementations include an extra callback, such as <code>glutWMCloseFunc()</code>.

Since it is no longer maintained (essentially replaced by the [[Open-source software|open source]] [[FreeGLUT]]) the above design issues are still not resolved in the original GLUT.