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: Mon, May 22, 1995

AFV