NAME

       barrier - synchronize execution of multiple shader invocations

DECLARATION

       void barrier(void);

DESCRIPTION

       Available only in the Tessellation Control and Compute Shaders, barrier provides a partially defined
       order of execution between shader invocations. For any given static instance of barrier, in a
       tessellation control shader, all invocations for a single input patch must enter it before any will be
       allowed to continue beyond it. For any given static instance of barrier in a compute shader, all
       invocations within a single work group must enter it before any are allowed to continue beyond it. This
       ensures that values written by one invocation prior to a given static instance of barrier can be safely
       read by other invocations after their call to the same static instance of barrier. Because invocations
       may execute in undefined order between these barrier calls, the values of a per-vertex or per-patch
       output variable, or any shared variable will be undefined in a number of cases.

       barrier may only be placed inside the function main() of the tessellation control shader, but may be
       placed anywhere in a compute shader. Calls to barrier may not be placed within any control flow. Barriers
       are also disallowed after a return statement in the function main().

VERSION SUPPORT

       ┌─────────┬───────────────────────────────────────────────────────────────────────────────────┐
       │         │        OpenGL Shading Language Version                                            │
       ├─────────┼──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┤
       │Function │ 1.10 │ 1.20 │ 1.30 │ 1.40 │ 1.50 │ 3.30 │ 4.00 │ 4.10 │ 4.20 │ 4.30 │ 4.40 │ 4.50 │
       │Name     │      │      │      │      │      │      │      │      │      │      │      │      │
       ├─────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤
       │barrier  │  -   │  -   │  -   │  -   │  -   │  -   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │
       └─────────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┘

COPYRIGHT

       Copyright © 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.  http://opencontent.org/openpub/.

COPYRIGHT

       Copyright © 2011-2014 Khronos Group

[FIXME: source]                                    01/03/2018                                        BARRIER(3G)