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Thread: Using gluUnProject

  1. #1
    Intern Contributor
    Join Date
    Feb 2000
    Location
    Italy
    Posts
    77

    Using gluUnProject

    I *really* can't find any way out of the gluUnProject function.
    What's supposed to be? When is it used?
    How is formed the matrix passed in the args?
    --
    Paolo M.

  2. #2
    Super Moderator OpenGL Guru
    Join Date
    Feb 2000
    Location
    Montreal, Canada
    Posts
    4,256

    Re: Using gluUnProject

    gluUnProject is used to convert from windows coordinate to object coordinate:

    example, a pixel's position might be (1, 1)

    if that pixel represents a rendered point in 3D space, what were it's original (x, y, z) values? Solution: gluUnProject() with 1, 1 and you must provide the depth value.

    You can use it for tests for one thing. If you don't need it, why worry about it?
    ------------------------------
    Sig: http://glhlib.sourceforge.net
    an open source GLU replacement library. Much more modern than GLU.
    float matrix[16], inverse_matrix[16];
    glhLoadIdentityf2(matrix);
    glhTranslatef2(matrix, 0.0, 0.0, 5.0);
    glhRotateAboutXf2(matrix, angleInRadians);
    glhScalef2(matrix, 1.0, 1.0, -1.0);
    glhQuickInvertMatrixf2(matrix, inverse_matrix);
    glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
    glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);

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