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 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

VERSION SUPPORT

       ┌────────────┬───────────────────────────────────────────────────────────────────────┐
       │            │                OpenGL Version                                         │
       ├────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │Function    │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
       │/           │     │     │     │     │     │     │     │     │     │     │     │     │
       │Feature     │     │     │     │     │     │     │     │     │     │     │     │     │
       │Name        │     │     │     │     │     │     │     │     │     │     │     │     │
       ├────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │glDepthFunc │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       └────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘

SEE ALSO

       glDepthRange(), glEnable(), glPolygonOffset()

COPYRIGHT

       Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2014 Khronos Group. This
       document is licensed under the SGI Free Software B License. For details, see
       http://oss.sgi.com/projects/FreeB/.

COPYRIGHT

       Copyright © 1991-2006 Silicon Graphics, Inc.
       Copyright © 2010-2014 Khronos Group

[FIXME: source]                             07/22/2015                            GLDEPTHFUNC(3G)