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man gluLookAt(3)
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```gluLookAt(3)                                                    gluLookAt(3)

```

## NAME

```       gluLookAt - define a viewing transformation

```

## C SPECIFICATION

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

```

## PARAMETERS

```       eyeX, eyeY, eyeZ
Specifies the position of the eye point.

centerX, centerY, centerZ
Specifies the position of the reference point.

upX, upY, upZ   Specifies the direction of the up vector.

```

## DESCRIPTION

```       gluLookAt  creates a viewing matrix derived from an eye point, a refer-
ence 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.  Sim-
ilarly,  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 point.

Let

centerX - eyeX
F = centerY - eyeY
centerZ - eyeZ

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

Then normalize as follows: f = F/ || F ||

UP' = UP/|| UP ||

Finally, let s = f X UP', and u = s X 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      1

and gluLookAt is equivalent to

glMultMatrixf(M);

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

```

## SEE ALSO

```       glFrustum, gluPerspective

gluLookAt(3)
```

Mac OS X 10.8 - Generated Sat Aug 25 18:27:18 CDT 2012
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