1GLULOOKAT(3G)                                                    GLULOOKAT(3G)
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NAME

6       gluLookAt - define a viewing transformation
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C SPECIFICATION

10       void gluLookAt( GLdouble eyeX,
11                       GLdouble eyeY,
12                       GLdouble eyeZ,
13                       GLdouble centerX,
14                       GLdouble centerY,
15                       GLdouble centerZ,
16                       GLdouble upX,
17                       GLdouble upY,
18                       GLdouble upZ )
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PARAMETERS

22       eyeX, eyeY, eyeZ
23                       Specifies the position of the eye point.
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25       centerX, centerY, centerZ
26                       Specifies the position of the reference point.
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28       upX, upY, upZ   Specifies the direction of the up vector.
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DESCRIPTION

31       gluLookAt  creates a viewing matrix derived from an eye point, a refer‐
32       ence point indicating the center of the scene, and an UP vector.
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34       The matrix maps the reference point to the negative z axis and the  eye
35       point  to  the  origin.   When a typical projection matrix is used, the
36       center of the scene therefore maps to the center of the viewport.  Sim‐
37       ilarly,  the  direction  described  by the UP vector projected onto the
38       viewing plane is mapped to the positive y axis so that it points upward
39       in  the  viewport.   The  UP vector must not be parallel to the line of
40       sight from the eye point to the reference point.
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42       Let
43          centerX − eyeX
44       F=⎛⎝centerY − eyeY⎞⎠
45          centerZ − eyeZ
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48       Let UP be the vector (upX,upY,upZ).
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50       Then normalize as follows: f=|_|_FF_|_|_
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52       UP′=|_|_UU_PP_|_|_
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55       Finally, let s=f×UP′, and u=s×f.
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57                                            s[0]  s[1]  s[2]  0
58       M is then constructed as follows: M=⎛⎝u[0]  u[1]  u[2]  0⎞⎠
59                                            −f[0] −f[1] −f[2] 0
60                                              0     0     0   1
61       and gluLookAt is equivalent to glMultMatrixf(M);  glTranslated  (-eyex,
62       -eyey, -eyez);
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SEE ALSO

65       glFrustum(3G), gluPerspective(3G)
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69                                                                 GLULOOKAT(3G)
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