Windows game loop

This is a discussion on Windows game loop within the Game Programming forums, part of the General Programming Boards category; A simple game loop might look like this: Code: while(!exit) { showIntro() while(game) { } } Writing a game loop ...

  1. #1
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    Windows game loop

    A simple game loop might look like this:
    Code:
    while(!exit)
    {
       showIntro()
       while(game)
       {
       }
    }
    Writing a game loop in using the Windows API doesn't seem so straight forward. What is one method?
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  2. #2
    Confused Magos's Avatar
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    I usually do this. It puts messages as first priority so they won't stack up.
    Code:
    msg Message;
    bool GameIsOn = true;
    
    while(GameIsOn)
    {
       if(PeekMessage(&Message, NULL, 0, 0))
       {
          TranslateMessage(&Message);
          DispatchMessage(&Message);
       }
       else
       {
          //Update/Render/Whatever
          //To quit, set GameIsOn to false
       }
    }
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  3. #3
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    Note the use of PeekMessage() rather than GetMessage().

    PeekMessage() will return if there is not a message, allowing the game to continue. This however maens that there will be no point where the game is doing nothing ie100% CPU use

    GetMessage() will not return until there is a message for the app. This means the app can sit dormant until it is needed. It will not be able to do background processing unless the app generates a timer msg (very inaccurate)



    To be 100% accurate should use the new message loop (which handles the -1 error return)

    Code:
    while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
    { 
        if (bRet == -1)
        {
            // handle the error and possibly exit
        }
        else
        {
            TranslateMessage(&msg); 
            DispatchMessage(&msg); 
        }
    }
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  4. #4
    Confused Magos's Avatar
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    But in a game loop you DO want to make calculations periodically wether a message has been sent or not. Using GetMessage, as you said, will halt execution until another message is sent.
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