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Thread: normals and rotations

  1. #1
    Intern Contributor
    Join Date
    Feb 2002
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    Wiesbaden, Germany
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    normals and rotations

    Hi,

    short question:

    If I have a normal in a certain vertex, and then rotate the vertex, do I have to rotate the normal too??
    I mean physically rotate it in 3D-space with sin and so on. Like rotating around Z-Axis 90. From my point of view I don't have to rotate the normal since it is situated perpendicular to a vertex, right??

    I'm a little confused about this topic since the last discussion with a colleague.

    Thanks,

    Martin

  2. #2
    Senior Member OpenGL Guru
    Join Date
    Feb 2000
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    Sweden
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    Re: normals and rotations

    The normal should be rotated with the object. If you rotate your object with OpenGL's own matrix functions, the normal will automatically be rotated.

  3. #3
    Intern Contributor
    Join Date
    Feb 2002
    Location
    Wiesbaden, Germany
    Posts
    95

    Re: normals and rotations

    Thanks Bob for solving this mysterie!

    Martin

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