**gluPerspective**

### NAME

**gluPerspective** -- set up a perspective projection matrix
### C SPECIFICATION

void **gluPerspective**(GLdouble *fovy*,
GLdouble *aspect*,
GLdouble *zNear*,
GLdouble *zFar*)

### PARAMETERS

*fovy*-
Specifies the field of view angle, in degrees, in the
*y* direction.

*aspect*-
Specifies the aspect ratio that determines the field of view in the
*x* direction. The aspect ratio is the ratio of *x* (width) to
*y* (height).

*zNear*-
Specifies the distance from the viewer to the near clipping plane (always
positive).

*zFar*-
Specifies the distance from the viewer to the far clipping plane (always
positive).

### DESCRIPTION

**gluPerspective** specifies a viewing frustum into the world coordinate
system. In general, the aspect ratio in **gluPerspective** should match the
aspect ratio of the associated viewport. For example, *aspect* = 2.0 means
the viewer's angle of view is twice as wide in *x* as it is in *y*.
If the viewport is twice as wide as it is tall, it displays the image without
distortion.
The matrix generated by **gluPerspective** is multipled by the current
matrix, just as if **glMultMatrix** were
called with the generated matrix. To load the perspective matrix onto the
current matrix stack instead, precede the call to **gluPerspective** with a
call to **glLoadIdentity**.

### SEE ALSO

**glFrustum**,
**glLoadIdentity**,
**glMultMatrix**,
**gluOrtho2D**

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© *1995 Uwe Behrens All rights reserved*