gluPerspective()gluPerspective()NAMEgluPerspective - set up a perspective projection matrix
SYNOPSIS
void gluPerspective(
GLdouble fovy,
GLdouble aspect,
GLdouble zNear,
GLdouble zFar );
PARAMETERS
Specifies the field of view angle, in degrees, in the y direction.
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).
Specifies the distance from the viewer to the near clipping plane
(always positive). Specifies the distance from the viewer to the far
clipping plane (always positive).
DESCRIPTIONgluPerspective() 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 glLoadIā
dentity().
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*zFar*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 ALSOglFrustum(3), glLoadIdentity(3), glMultMatrix(3), gluOrtho2D(3)gluPerspective()