Synchronize execution of multiple shader invocations.
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 functionmain()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 functionmain().
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