
GLUPERSPECTIVE(3G) OpenGL Manual GLUPERSPECTIVE(3G)
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().
Given f defined as follows:
f = cotangent fovy 2 The generated matrix is
f aspect 0 0 0 0 f 0 0 0 0 zFar + zNear zNear  zFar 2 x zFar x zNear zNear  zFar 0 0 1
0
NOTES
Depth buffer precision is affected by the values specified for zNear and zFar. The greater
the ratio of zFar to zNear is, the less effective the depth buffer will be at
distinguishing between surfaces that are near each other. If
r = zFar zNear
roughly log 2 r bits of depth buffer precision are lost. Because r approaches infinity as
zNear approaches 0, zNear must never be set to 0.
SEE ALSO
gluOrtho2D(), glFrustum(), glLoadIdentity(), glMultMatrix()
COPYRIGHT
Copyright (C) 19912006 Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 06/10/2014 GLUPERSPECTIVE(3G) 
