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tc_tianchao

OpenGL OpenGL exclusive fullscreen mode

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tc_tianchao    122
Hi, As I know, in Direct3D, there are windowed mode and fullscreen mode in which the application uses the video card exclusively. My question is, in OpenGL, is there such an exclusive fullscreen mode? If yes, how can I switch my applications into that mode. Thanks a lot!

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Undeadlnsanity    233
When creating an OpenGL window you set the fullscreen parameter.

E.G:
CreateGLWindow("Window Title",640,480,16,TRUE)


The first param is the window title, the second is the height, third is the width, fourth is the colour depth and the fifth is fullscreen.

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tc_tianchao    122
Thanks a lot, Undeadlnsanity!

But is "CreateGLWindow" a standard OpenGL call? In fact, what I want to do is to detect an exclusive fullscreen OpenGL application. I think I need to hook the OpenGL method that an application may use to switch itself into fullscreen mode. Is there such a standard OpenGL method?

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markr    1692
Quote:
Original post by tc_tianchao
My question is, in OpenGL, is there such an exclusive fullscreen mode?


That depends entirely on the operating system and environment. Yes, some systems (for example, Windows, Linux and MacOS) do provide this feature, but the method for doing it is platform-specific.

Some platforms of course support nothing else (Consoles, DOS)

Quote:

If yes, how can I switch my applications into that mode. Thanks a lot!


In some cases you can't "switch" your applications into that mode, you have to choose it at startup (i.e. when (or before) the gl context is created).

Mark

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tc_tianchao    122
Thanks, Geocyte and markr!

In fact, I only care about Windows OS.

markr, do you mean that an application needs to call Windows APIs such as "ChangeDisplaySettings" to get itself in fullscreen mode, and OpenGL itself has no such functionality since it is platform independent?

Actually, what I want to find out is what an OpenGL application will do if it wants to use the video card EXCLUSIVELY. (I don't think "ChangeDisplaySettings" can tell the system whether the application will use the video card exclusively.) Thanks a lot!

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kburkhart84    3187
The CreateGLWindow looks like the NEHE function that wraps up most of the intialization required to get OpenGL running. Using ChangeDisplaySetting correctly should work. I don't understand why you need "exclusive" mode for anything. I think you should go fullscreen mode and leave it at that. Remember, the user might want to alt-tab out of the game so you need to be set up for that to happen. This applies especially in a windows environment because that is why windows was made the way it was, multi-tasking.

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blanky    364
I think he means that when it goes fullscreen, if you can make it so that only that application has access to the video card, in other words, the video card is all to program when it's in fullscreen.

Also, CreateGLWindow, that's a real function? What library/header?

EDIT: Either it's from SDL or you create it yourself, if you want to know how to create it yourself, I found a very nice page: http://www.morrowland.com/apron/tutorials/gl/gl_window.php

Also, to not waste space and create a new thread, is it possible to go into Fullscreen once already running the app? I know it is, what a dumb question, cause I've seen it in games, but can anyone refer me to any code that does this? Thanks.

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tc_tianchao    122
Thanks, guys!

kburkhart84, this is why I need to know what an OpenGL app will do if it wants to use the video card exclusively. While an exclusive fullscreen game is running, if I start a second exclusive fullscreen game (maybe by calling "CreateProcess" in a program), there will be a conflict and the second game may fail. What I need to do is to detect such games so that I can do something to prevent the conflict to happen. Does anyone have an idea?

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blanky    364
Yeah I know what you mean, but again, you have to take it slowly. First, what you should know is how to get that exclusive clearance from the video card. What he means, guys, is that how can you make it so that when you run in fullscreen, to have it where only that program can access the video card. Unless this automatically happens, he claims that DirectX has this feature. I'm very interested in this feautre in OpenGL as well, although I dont think there's such thing since OpenGL is more cross platform.

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kburkhart84    3187
Well, if you are trying to multi-task, as in letting the user alt-tab so he can do something else, then you shouldn't be trying to get exclusive control in the first place. Then, I really don't think anyone is going to want to run two CPU hungry fullscreen games at once. And if they do, I say let them. If they run out of memory, it is their own problem. But, I think you should allow them to run another program, even if it is another full screen application like yours. I don't even think you need to detect it, rather when your application is reactivated, recreate the fullscreen part, though the window just needs maximized. So, my opinion is just to be as compatible as possible and don't try to take over the computer.

Also, I think that unless your program itself starts another one, I don't think it will start by itself. If it does, like maybe internet popups or something like it, the screen will probably keep the same resolution etc... that you have it at and "tab out" of your application, just like if the user had done it, then giving focus to the "new" application, full-screen or not.

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tc_tianchao    122
kburkhart84, first, I'd like to make it clear that I am not a game developer, instead, I am working on a gaming system that hosts existing OpenGL/D3D/DDraw games. So it is out of my control whether a game goes into fullscreen mode or not. Actually, in our system, we force a game to run in background mode and send the game video and audio to a remote machine through network. So there is possibility that a user on the host machine starts a new fullscreen application. In such a case, we found that the new application might cause the game running in background mode to fail and affected the experience of the remote game player. So we have to detect such a second fullscreen application and either stop it from running or force it to use the video card non-exclusively. We have found solutions to D3D/DDraw applications but we don't know how to deal with OpenGL. That is where my question comes from.

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kburkhart84    3187
I see....... That changes things a little bit. I'm glad you explained that to me. The problem I see is that windows itself automatically gets out of an app or game when another window takes the focus. I think you might could somehow grab the "lost-focus" message, (don't remember what it's called), and somehow react to it. I have heard of message hooks as well that I think allow you to get other windows messages, but they might have to be your own windows. That is about all the help I think I have for this situation. I tried though. Post any results you get. I'd like to see.

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