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  man pages->Tru64 Unix man pages -> gluLookAt (3)              


gluLookAt()                                           gluLookAt()

NAME    [Toc]    [Back]

       gluLookAt - define a viewing transformation

SYNOPSIS    [Toc]    [Back]

       void gluLookAt(
               GLdouble eyeX,
               GLdouble eyeY,
               GLdouble eyeZ,
               GLdouble centerX,
               GLdouble centerY,
               GLdouble centerZ,
               GLdouble upX,
               GLdouble upY,
               GLdouble upZ );

PARAMETERS    [Toc]    [Back]

       Specifies  the  position  of the eye point.  Specifies the
       position of the reference point.  Specifies the  direction
       of the up vector.

DESCRIPTION    [Toc]    [Back]

       gluLookAt()  creates  a viewing matrix derived from an eye
       point, a reference point  indicating  the  center  of  the
       scene, and an UP vector.

       The matrix maps the reference point to the negative z axis
       and the eye point to the origin. When a typical projection
       matrix  is used, the center of the scene therefore maps to
       the center of  the  viewport.   Similarly,  the  direction
       described  by  the  UP  vector  projected onto the viewing
       plane is mapped to the positive y axis so that  it  points
       upward in the viewport. The UP vector must not be parallel
       to the line of sight from the eye point to  the  reference

            centerX - eyeX F =  centerY - eyeY
            centerZ - eyeZ

       Let UP be the vector (upX, upY, upZ).

       Then  normalize  as  follows:  f = F / ||F|| UP^prime = UP

       Finally, let s = f times UP^prime, and u = s times f.

       M is then constructed as follows:
            s[0]    s[1]    s[2]    0

            u[0]    u[1]    u[2]    0 M =

            -f[0]  -f[1]   -f[2]    0

              0      0       0      0

       and  gluLookAt()  is   equivalent   to   glMultMatrixf(M);
       glTranslated (-eyex, -eyey, -eyez);

SEE ALSO    [Toc]    [Back]

       glFrustum(3), gluPerspective(3)

[ Back ]
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