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Thread: OpenGL overlay

  1. #1
    Junior Member Newbie
    Join Date
    Apr 2004
    Location
    Hajom, Sweden
    Posts
    1

    OpenGL overlay

    Hi everyone!
    Is it possible to draw an overlay using opengl?
    what I wan't to do is draw over a window where graphics is already drawed, so I don't want to use opengl in that actual window. you get it?
    So close, and yet so far away...

  2. #2
    Junior Member Newbie
    Join Date
    Apr 2004
    Location
    MilkyWay
    Posts
    6

    Re: OpenGL overlay

    I'm an opengl newbie myself, first post and all, but I did something like this awhile back.

    Only way I could find at the time was :

    1.) grab a handle to the window you need to draw on
    2.) either use setpixel (slow)
    3.) getpixel works (slow)
    4.) BitBlt works as well, to and from a memDC

    so as to printing out a window inside an already open , OpenGL window... I guess you could either 'create' a window lookalike on the current hdc, or memDC, and bitblt it over.. it's not that slow..

    well, hope I helped a little..

    D

  3. #3
    Junior Member Newbie
    Join Date
    Apr 2004
    Location
    MilkyWay
    Posts
    6

    Re: OpenGL overlay

    oops!!

    I forgot to mention the flicker. If you decide to try that, the screen where you are drawing on the OpenGL window, will flicker.. Due to buffering. Wish I knew how to fix that, but it's been awhile since I messed with it.

    Maybe some sort of buffer, have no idea how to access the opengl buffer. If anyone else knows that , I myself would be happy to see it work

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