very simple question

This is a discussion on very simple question within the Windows Programming forums, part of the Platform Specific Boards category; Hi,guys In the game,how could I make the background to keep moving with only one ground bitmap? Is there any ...

  1. #1
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    Unhappy very simple question

    Hi,guys

    In the game,how could I make the background to keep moving with only one ground bitmap?
    Is there any trick for this?

    ThanX!!
    Don't laugh at me,I am just a SuperNewbie.

  2. #2
    Used Registerer jdinger's Avatar
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    If you mean moving like side-scrolling then you can try this:

    Say for instance your game screen is 300 pixels wide and your
    background bitmap 300 pixels wide too. Define a variable (int i for
    our purposes) to hold the start of your bitmap (at first this would
    be 0). When needed (say the user pushes the right arrow key to
    make your hero walk), you incriment the bitmap start int. In your
    blit routine you would test to see if(i==0). If so, then blit your
    bitmap starting a 0. If not, run a blit 2 instances of your bitmap.
    The first will have a Source X of whatever i equals, will have a
    width of (300-i) and will have a Destination X of 0. The second will
    have a Source X of 0, a width of (300-i) and a Destination X of i.

    Here's an example (pseudo) of this if the hero walks 10 pixels to
    the right:

    Code:
    //look, Ma! Code tags! 
    
    if(i==0)
    {
       blit grass.bmp starting at destinatin 0 with source width of 300 
    and source starting at 0
    }
    else
    {
      //1st part
      blit grass.bmp starting at destination 0 with source width of 290 
    and source starting at 10
    
      //2nd part
      blit grass.bmp starting at destination 290 with source width of 
    10 and source starting at 0
    }
    If this isn't what you're looking for let me know and hopefully I
    can explain another method.

  3. #3
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    /////------------------------------------------------------------------------------

    If not, run a blit 2 instances of your bitmap.
    The first will have a Source X of whatever i equals, will have a
    width of (300-i) and will have a Destination X of 0. The second will
    have a Source X of 0, a width of (300-i) and a Destination X of i.

    ////-------------------------------------------------------------------------------


    Thank you very much for the help, but about the blit 2, you mean
    first have a source X of whatever i equals, and the width of (300-i)
    and blit to destination X of 0. The second will have a source of 0, a width of i and destination start of (300-i)

    and test
    (if i ==300)
    i= 0;
    blit 1;

    am I right?
    Don't laugh at me,I am just a SuperNewbie.

  4. #4
    Used Registerer jdinger's Avatar
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    and test
    (if i ==300)
    i= 0;
    blit 1;
    Yes. Sorry I forgot to mention checking for i==300 to reset itself,
    but that's right.

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