Game Mode
[OpenGLEAN API Reference]

Collaboration diagram for Game Mode:

DEPRECATED

It has always been buggy/incomplete in freeglut and OpenGLUT. It is poorly defined. It was never documented by GLUT (that I have seen). freeglut attempted to recreate it by guesswork, and OpenGLUT only fixed some of freeglut's bugs. It is impossible for the API to be made uniform without breaking some people's uses. Some systems will only give you partial success, but you cannot tell whether you got what you asked for. Do not use this feature.

OpenGLEAN intends to provide the functionality of gamemode in a better defined API.

Game mode provides an exclusive full-screen mode of operation for applications such as games.

Game mode suffers from some serious problems, however.

Bug:

It behaves differently on different systems. E.g., on some X systems, changing the video mode is impossible. This has led some developers to use game mode as a ``grab the mouse'' mode, without intending a resolution change.

Replacing game mode with a better design was discussed at some length in early 2004.

One idea was to decompose gamemode into component parts and implement them separately, where each part then either succeeds totally or fails totally:

• Resolution change.
• Fullscreen.
• Focus grabbing.
• Settable video frequencies at current resolution. Applications could ask for any or all of these separately. Some of this is already apparently intended in unimplemented API entry points inherited from freeglut. However, the meaning of the entry points is undocumented.

There is no way for game mode to report a partial failure.

There is no way to guarantee cleanup if OpenGLEAN crashes during game mode---or if the client crashes or directly exits, etc.

Some XFree86 releases, with some drivers, can fail to set the video mode properly, resulting in disasterous failure (an unusable display). This is presently somewhat headed off by a compile-time option, but a runtime option would be better, as there may be cases where the user is willing to put up with the risk for some---and only some---OpenGLEAN applications. Since game mode applications are somewhat dim-witted about such user preferences, it seems, an OpenGLEAN runtime control could be desirable.

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