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# CentOS 7.0 - man page for glulookat (centos section 3g)

```GLULOOKAT(3G)					    OpenGL Manual					GLULOOKAT(3G)

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 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 point.

Let

F = centerX - eyeX 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: M = s	0 s  1 s  2 0 u  0 u  1 u  2 0 - f  0 - f  1 - f  2 0 0 0 0 1

and gluLookAt is equivalent to

glMultMatrixf(M);
glTranslated(-eyex, -eyey, -eyez);

gluPerspective(), glFrustum()

AUTHORS
opengl.org

opengl.org					      06/10/2014					GLULOOKAT(3G)```

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