GLAPI/glDepthFunc: Difference between revisions

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== Function Definition ==
== Function Definition ==


   void '''glDepthFunc'''(GLenum ''func'');
   void '''glDepthFunc'''(GLenum {{param|func}});


; func
; func
: Specifies the depth comparison function. Symbolic constants {{code|GL_NEVER}}, {{code|GL_LESS}}, {{code|GL_EQUAL}}, {{code|GL_LEQUAL}}, {{code|GL_GREATER}}, {{code|GL_NOTEQUAL}}, {{code|GL_GEQUAL}}, and {{code|GL_ALWAYS}} are accepted. The initial value is {{code|GL_LESS}}.
: Specifies the depth comparison function. Symbolic constants {{enum|GL_NEVER}}, {{enum|GL_LESS}}, {{enum|GL_EQUAL}}, {{enum|GL_LEQUAL}}, {{enum|GL_GREATER}}, {{enum|GL_NOTEQUAL}}, {{enum|GL_GEQUAL}}, and {{enum|GL_ALWAYS}} are accepted. The initial value is {{enum|GL_LESS}}.


== Description ==
== Description ==


'''glDepthFunc''' specifies the function used to compare each incoming pixel depth value with the depth value present in the depth buffer. The comparison is performed only if depth testing is enabled. (See [[GLAPI/glEnable|glEnable]] and [[GLAPI/glDisable|glDisable]] of {{code|GL_DEPTH_TEST}}.)
'''glDepthFunc''' specifies the function used to compare each incoming pixel depth value with the depth value present in the depth buffer. The comparison is performed only if depth testing is enabled. (See {{apifunc|glEnable}} and {{apifunc|glDisable}} of {{enum|GL_DEPTH_TEST}}.)


''func'' specifies the conditions under which the pixel will be drawn. The comparison functions are as follows:
{{param|func}} specifies the conditions under which the pixel will be drawn. The comparison functions are as follows:


; {{code|GL_NEVER}}
; {{enum|GL_NEVER}}
: Never passes.
: Never passes.
; {{code|GL_LESS}}
; {{enum|GL_LESS}}
: Passes if the incoming depth value is less than the stored depth value.
: Passes if the incoming depth value is less than the stored depth value.
; {{code|GL_EQUAL}}
; {{enum|GL_EQUAL}}
: Passes if the incoming depth value is equal to the stored depth value.
: Passes if the incoming depth value is equal to the stored depth value.
; {{code|GL_LEQUAL}}
; {{enum|GL_LEQUAL}}
: Passes if the incoming depth value is less than or equal to the stored depth value.
: Passes if the incoming depth value is less than or equal to the stored depth value.
; {{code|GL_GREATER}}
; {{enum|GL_GREATER}}
: Passes if the incoming depth value is greater than the stored depth value.
: Passes if the incoming depth value is greater than the stored depth value.
; {{code|GL_NOTEQUAL}}
; {{enum|GL_NOTEQUAL}}
: Passes if the incoming depth value is not equal to the stored depth value.
: Passes if the incoming depth value is not equal to the stored depth value.
; {{code|GL_GEQUAL}}
; {{enum|GL_GEQUAL}}
: Passes if the incoming depth value is greater than or equal to the stored depth value.
: Passes if the incoming depth value is greater than or equal to the stored depth value.
; {{code|GL_ALWAYS}}
; {{enum|GL_ALWAYS}}
: Always passes.
: Always passes.
The initial value of ''func'' is {{code|GL_LESS}}. Initially, depth testing is disabled. If depth testing is disabled or if no depth buffer exists, it is as if the depth test always passes.
The initial value of {{param|func}} is {{enum|GL_LESS}}. Initially, depth testing is disabled. If depth testing is disabled or if no depth buffer exists, it is as if the depth test always passes.


== Notes ==
== Notes ==


Even if the depth buffer exists and the depth mask is non-zero, the depth buffer is not updated if the depth test is disabled. In order to unconditionally write to the depth buffer, the depth test should be enabled and set to {{code|GL_ALWAYS}}.
Even if the depth buffer exists and the depth mask is non-zero, the depth buffer is not updated if the depth test is disabled. In order to unconditionally write to the depth buffer, the depth test should be enabled and set to {{enum|GL_ALWAYS}}.


== Errors ==
== Errors ==


{{code|GL_INVALID_ENUM}} is generated if ''func'' is not an accepted value.
{{enum|GL_INVALID_ENUM}} is generated if {{param|func}} is not an accepted value.


== Associated Gets ==
== Associated Gets ==


[[GLAPI/glGet|glGet]] with argument {{code|GL_DEPTH_FUNC}}
{{apifunc|glGet}} with argument {{enum|GL_DEPTH_FUNC}}


[[GLAPI/glIsEnabled|glIsEnabled]] with argument {{code|GL_DEPTH_TEST}}
{{apifunc|glIsEnabled}} with argument {{enum|GL_DEPTH_TEST}}


== See Also ==
== See Also ==


[[GLAPI/glDepthRange|glDepthRange]], [[GLAPI/glEnable|glEnable]], [[GLAPI/glPolygonOffset|glPolygonOffset]]
{{apifunc|glEnable|(GL_DEPTH_TEST)}}, {{apifunc|glDepthRange}}, {{apifunc|glPolygonOffset}}


== Copyright ==
== Copyright ==


Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [http://oss.sgi.com/projects/FreeB/ http://oss.sgi.com/projects/FreeB/].
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt LicenseRef-FreeB].


[[Category:API Reference 4|DepthFunc]]
[[Category:Core API Ref Post Fragment Shader Operations|DepthFunc]]
[[Category:GL 4 API Post Fragment Shader Operations|DepthFunc]]
[[Category:Core API Reference|DepthFunc]]

Latest revision as of 21:37, 5 February 2021

glDepthFunc
Core in version 4.6
Core since version 1.0

glDepthFunc: specify the value used for depth buffer comparisons

Function Definition

 void glDepthFunc(GLenum func​);
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 initial value is GL_LESS.

Description

glDepthFunc specifies the function used to compare each incoming pixel depth value with the depth 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 depth value is less than the stored depth value.
GL_EQUAL
Passes if the incoming depth value is equal to the stored depth value.
GL_LEQUAL
Passes if the incoming depth value is less than or equal to the stored depth value.
GL_GREATER
Passes if the incoming depth value is greater than the stored depth value.
GL_NOTEQUAL
Passes if the incoming depth value is not equal to the stored depth value.
GL_GEQUAL
Passes if the incoming depth value is greater than or equal to the stored depth value.
GL_ALWAYS
Always passes.

The initial value of func​ is GL_LESS. Initially, depth testing is disabled. If depth testing is disabled or if no depth buffer exists, it is as if the depth test always passes.

Notes

Even if the depth buffer exists and the depth mask is non-zero, the depth buffer is not updated if the depth test is disabled. In order to unconditionally write to the depth buffer, the depth test should be enabled and set to GL_ALWAYS.

Errors

GL_INVALID_ENUM is generated if func​ is not an accepted value.

Associated Gets

glGet with argument GL_DEPTH_FUNC

glIsEnabled with argument GL_DEPTH_TEST

See Also

glEnable(GL_DEPTH_TEST), glDepthRange, glPolygonOffset

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see LicenseRef-FreeB.

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