'\" t
.\"     Title: glDepthFunc
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 01/03/2018
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "GLDEPTHFUNC" "3G" "01/03/2018" "[FIXME: source]" "[FIXME: manual]"
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.SH "NAME"
glDepthFunc \- specify the value used for depth buffer comparisons
.SH "C SPECIFICATION"
.HP \w'void\ glDepthFunc('u
.BI "void glDepthFunc(GLenum\ " "func" ");"
.SH "PARAMETERS"
.PP
\fIfunc\fR
.RS 4
Specifies the depth comparison function\&. Symbolic constants
\fBGL_NEVER\fR,
\fBGL_LESS\fR,
\fBGL_EQUAL\fR,
\fBGL_LEQUAL\fR,
\fBGL_GREATER\fR,
\fBGL_NOTEQUAL\fR,
\fBGL_GEQUAL\fR, and
\fBGL_ALWAYS\fR
are accepted\&. The initial value is
\fBGL_LESS\fR\&.
.RE
.SH "DESCRIPTION"
.PP
\fBglDepthFunc\fR
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
\fBglEnable\fR()
and

\fBglDisable\fR
of
\fBGL_DEPTH_TEST\fR\&.)
.PP
\fIfunc\fR
specifies the conditions under which the pixel will be drawn\&. The comparison functions are as follows:
.PP
\fBGL_NEVER\fR
.RS 4
Never passes\&.
.RE
.PP
\fBGL_LESS\fR
.RS 4
Passes if the incoming depth value is less than the stored depth value\&.
.RE
.PP
\fBGL_EQUAL\fR
.RS 4
Passes if the incoming depth value is equal to the stored depth value\&.
.RE
.PP
\fBGL_LEQUAL\fR
.RS 4
Passes if the incoming depth value is less than or equal to the stored depth value\&.
.RE
.PP
\fBGL_GREATER\fR
.RS 4
Passes if the incoming depth value is greater than the stored depth value\&.
.RE
.PP
\fBGL_NOTEQUAL\fR
.RS 4
Passes if the incoming depth value is not equal to the stored depth value\&.
.RE
.PP
\fBGL_GEQUAL\fR
.RS 4
Passes if the incoming depth value is greater than or equal to the stored depth value\&.
.RE
.PP
\fBGL_ALWAYS\fR
.RS 4
Always passes\&.
.RE
.PP
The initial value of
\fIfunc\fR
is
\fBGL_LESS\fR\&. 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\&.
.SH "NOTES"
.PP
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
\fBGL_ALWAYS\fR\&.
.SH "ERRORS"
.PP
\fBGL_INVALID_ENUM\fR
is generated if
\fIfunc\fR
is not an accepted value\&.
.SH "ASSOCIATED GETS"
.PP
\fBglGet\fR()
with argument
\fBGL_DEPTH_FUNC\fR
.PP
\fBglIsEnabled\fR()
with argument
\fBGL_DEPTH_TEST\fR
.SH "VERSION SUPPORT"
.TS
allbox tab(:);
lB cB s s s s s s s s s s s
lB cB cB cB cB cB cB cB cB cB cB cB cB.
T{

T}:T{
\fBOpenGL Version\fR
T}
T{
\fBFunction / Feature Name\fR
T}:T{
\fB2\&.0\fR
T}:T{
\fB2\&.1\fR
T}:T{
\fB3\&.0\fR
T}:T{
\fB3\&.1\fR
T}:T{
\fB3\&.2\fR
T}:T{
\fB3\&.3\fR
T}:T{
\fB4\&.0\fR
T}:T{
\fB4\&.1\fR
T}:T{
\fB4\&.2\fR
T}:T{
\fB4\&.3\fR
T}:T{
\fB4\&.4\fR
T}:T{
\fB4\&.5\fR
T}
.T&
l c c c c c c c c c c c c.
T{
\fBglDepthFunc\fR
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}
.TE
.sp 1
.SH "SEE ALSO"
.PP
\fBglDepthRange\fR(),
\fBglEnable\fR(),
\fBglPolygonOffset\fR()
.SH "COPYRIGHT"
.PP
Copyright
\(co
1991\-2006 Silicon Graphics, Inc\&. Copyright
\(co
2010\-2014 Khronos Group\&. This document is licensed under the SGI Free Software B License\&. For details, see
\m[blue]\fBhttp://oss\&.sgi\&.com/projects/FreeB/\fR\m[]\&.
.SH "COPYRIGHT"
.br
Copyright \(co 1991-2006 Silicon Graphics, Inc.
.br
Copyright \(co 2010-2014 Khronos Group
.br