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.\"     Title: gl_PrimitiveID
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 05/21/2015
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "GL_PRIMITIVEID" "3G" "05/21/2015" "[FIXME: source]" "[FIXME: manual]"
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.SH "NAME"
gl_PrimitiveID \- contains the index of the current primitive
.SH "DECLARATION"
.PP
.nf
// In tessellation control, tessellation evaluation, and
// fragment shaders
.fi
.sp
in\ \&int\ \&gl_PrimitiveID\ \&;
.PP
.nf
// In geometry shaders
.fi
.sp
out\ \&int\ \&gl_PrimitiveID\ \&;
.SH "DESCRIPTION"
.PP
\fIgl_PrimitiveID\fR
is a tessellation control, tessellation evaluation and fragment language input variable\&. For the tessellation control and tessellation evaluation languages, it holds the number of primitives processed by the shader since the current set of rendering primitives was started\&. The first primitive processed by the drawing command is numbered zero and the primitive ID counter is incremented after every individual point, line or triangle primitive is processed\&. For triangles drawn in point or line mode, the primitive ID counter is incremented only once, even through multiple points or lines may actually be drawn\&. Restarting a primitive topology using the primitive restart index has no effect on the primitive ID counter\&.
.PP
In the geometry language,
\fIgl_PrimitiveID\fR
is an output variable that is passed to the corresponding
\fIgl_PrimitiveID\fR
input variable in the fragment shader\&. If no geomery shader is present then
\fIgl_PrimitiveID\fR
in the fragment language behaves identically as it would in the tessellation control and evaluation languages\&. If a geometry shader is present but does not write to
\fIgl_PrimitiveID\fR, the value of
\fIgl_PrimitiveID\fR
in the fragment shader is undefined\&.
.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 Shading Language Version\fR
T}
T{
\fBFunction Name\fR
T}:T{
\fB1\&.10\fR
T}:T{
\fB1\&.20\fR
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\fB1\&.30\fR
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\fB1\&.40\fR
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\fB1\&.50\fR
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\fB3\&.30\fR
T}:T{
\fB4\&.00\fR
T}:T{
\fB4\&.10\fR
T}:T{
\fB4\&.20\fR
T}:T{
\fB4\&.30\fR
T}:T{
\fB4\&.40\fR
T}:T{
\fB4\&.50\fR
T}
.T&
l c c c c c c c c c c c c
l c c c c c c c c c c c c.
T{
\fIgl_PrimitiveID\fR (Fragment and Geometry Languages)
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}
T{
\fIgl_PrimitiveID\fR (Tessellation Control and Evaluation Languages)
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
.SH "SEE ALSO"
.PP
\fBgl_InstanceID\fR(),
\fBgl_VertexID\fR(),
\fBgl_PrimitiveIDIn\fR()
.SH "COPYRIGHT"
.PP
Copyright
\(co
2011\-2014 Khronos Group\&. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1\&.0, 8 June 1999\&.
\m[blue]\fBhttp://opencontent\&.org/openpub/\fR\m[]\&.
.SH "COPYRIGHT"
.br
Copyright \(co 2011-2014 Khronos Group
.br