Index for Section 3

Alphabetical listing for G

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gluPerspective()
NAME
  gluPerspective - set up a perspective projection matrix

SYNOPSIS
  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*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 ALSO
  glFrustum(3), glLoadIdentity(3), glMultMatrix(3), gluOrtho2D(3)

Index for Section 3

Alphabetical listing for G

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