glDepthFunc.3gl

Name

  glDepthFunc -	specify	the value used for depth buffer	comparisons

C Specification

  void glDepthFunc( GLenum func	)

Parameters

  func	Specifies the depth comparison function.  Symbolic constants
	GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL,	GL_GREATER, GL_NOTEQUAL,
	GL_GEQUAL, and GL_ALWAYS are accepted.	The default value is GL_LESS.

Description

  glDepthFunc specifies	the function used to compare each incoming pixel z
  value	with the z value present in the	depth buffer.  The comparison is
  performed only if depth testing is enabled.  (See glEnable and glDisable of
  GL_DEPTH_TEST.)

  func specifies the conditions	under which the	pixel will be drawn.  The
  comparison functions are as follows:

  GL_NEVER	      Never passes.

  GL_LESS	      Passes if	the incoming z value is	less than the stored
		      z	value.

  GL_EQUAL	      Passes if	the incoming z value is	equal to the stored z
		      value.

  GL_LEQUAL	      Passes if	the incoming z value is	less than or equal to
		      the stored z value.

  GL_GREATER	      Passes if	the incoming z value is	greater	than the
		      stored z value.

  GL_NOTEQUAL	      Passes if	the incoming z value is	not equal to the
		      stored z value.

  GL_GEQUAL	      Passes if	the incoming z value is	greater	than or	equal
		      to the stored z value.

  GL_ALWAYS	      Always passes.

  The default value of func is GL_LESS.	 Initially, depth testing is
  disabled.

Errors

  GL_INVALID_ENUM is generated if func is not an accepted value.


  GL_INVALID_OPERATION is generated if glDepthFunc is executed between the
  execution of glBegin and the corresponding execution of glEnd.

Associated Gets

  glGet	with argument GL_DEPTH_FUNC
  glIsEnabled with argument GL_DEPTH_TEST

See Also

  glDepthRange,	glEnable

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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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