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Thread: The Solution for gluLookAt() Function!!!!

  1. #1
    Junior Member
    Join Date
    Jan 2005

    The Solution for gluLookAt() Function!!!!

    i posted long time ago a thread asking of how to use a gluLookAt()-like fnction in OpenGL ES since it is not supported in the API until now. i have implemented my own version of it for Symbian OS and thought it would be useful post it for thos who might need it.
    i hope u find it useful

    // to perform cross product between 2 vectors in myGluLookAt
    void CrossProd(float x1, float y1, float z1, float x2, float y2, float z2, float res[3])
    res[0] = y1*z2 - y2*z1;
    res[1] = x2*z1 - x1*z2;
    res[2] = x1*y2 - x2*y1;

    // my own implementation
    void FadiGluLookAt(float eyeX, float eyeY, float eyeZ, float lookAtX, float lookAtY, float lookAtZ, float upX, float upY, float upZ)
    // i am not using here proper implementation for vectors.
    // if you want, you can replace the arrays with your own
    // vector types
    float f[3];

    // calculating the viewing vector
    f[0] = lookAtX - eyeX;
    f[1] = lookAtY - eyeY;
    f[2] = lookAtZ - eyeZ;

    TReal fMag, upMag;
    Math::Sqrt(fMag, f[0]*f[0] + f[1]*f[1] + f[2]*f[2]);
    Math::Sqrt(upMag, upX*upX + upY*upY + upZ*upZ);

    // normalizing the viewing vector
    if( fMag != 0)
    f[0] = f[0]/fMag;
    f[1] = f[1]/fMag;
    f[2] = f[2]/fMag;

    // normalising the up vector. no need for this here if you have your
    // up vector already normalised, which is mostly the case.
    if( upMag != 0 )
    upX = upX/upMag;
    upY = upY/upMag;
    upZ = upZ/upMag;

    float s[3], u[3];

    CrossProd(f[0], f[1], f[2], upX, upY, upZ, s);
    CrossProd(s[0], s[1], s[2], f[0], f[1], f[2], u);

    float M[]=
    s[0], u[0], -f[0], 0,
    s[1], u[1], -f[1], 0,
    s[2], u[2], -f[2], 0,
    0, 0, 0, 1

    glTranslatef (-eyeX, -eyeY, -eyeZ);

  2. #2
    Join Date
    May 2005
    It's very interest!

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