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Thread: zooming using gluOrtho2D

  1. #1
    Newbie Newbie
    Join Date
    Mar 2018
    Posts
    1

    zooming using gluOrtho2D

    Hi,

    I'm wondering if somebody could help me figure out how to zoom in/out in 2D using gluOrtho2D.
    Currently I have glViewport(0, 0, 400, 300) and gluOrtho2D(0.0, 400.0, 0.0, 300.0) but I am uncertain as to how these work together.
    So, how might I do this and maintain aspect ratio so the objects in the view don't get stretched and stay in the center of the window?

    Thanks!

  2. #2
    Senior Member OpenGL Guru
    Join Date
    Jun 2013
    Posts
    2,829
    To preserve the aspect ratio, the ratio (r-l)/(t-b) for gluOrtho2D() should be equal to w/h for glViewport().

    But if you just want to zoom by a specific factor, it's probably simpler to just apply a glScale() transformation to the projection matrix after gluOrtho2D().

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