clCreateEventFromGLsyncKHR
clCreateEventFromGLsyncKHR
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clCreateEventFromGLsyncKHR Creates an event object linked to an OpenGL sync object.

##

cl_event `clCreateEventFromGLsyncKHR` cl_context context GLsyncsync cl_int*errcode_ret

## Parameters

`context`

  A valid OpenCL context created from an OpenGL context or share group, using the cl_khr_gl_sharing extension.

`sync`

  The name of a sync object in the GL share group associated with `context`.

## Description

An event object may be created by linking to an OpenGL sync object. Completion of such an event object is equivalent to waiting for completion of the fence command associated with the linked GL sync object.

## Notes

The parameters of an event object linked to a GL sync object will return the following values when queried with clGetEventInfo:

- The `CL_EVENT_COMMAND_QUEUE` of a linked event is NULL, because the event is not associated with any OpenCL command queue.
- The `CL_EVENT_COMMAND_TYPE` of a linked event is `CL_COMMAND_GL_FENCE_SYNC_OBJECT_KHR`, indicating that the event is associated with a GL sync object, rather than an OpenCL command.
- The `CL_EVENT_COMMAND_EXECUTION_STATUS` of a linked event is either `CL_SUBMITTED`, indicating that the fence command associated with the sync object has not yet completed, or `CL_COMPLETE`, indicating that the fence command has completed.

`clCreateEventFromGLsyncKHR` performs an implicit clRetainEvent on the returned event object. Creating a linked event object also places a reference on the linked GL sync object. When the event object is deleted, the reference will be removed from the GL sync object.

Events returned from `clCreateEventFromGLsyncKHR` may only be consumed by clEnqueueAcquireGLObjects. Passing such events to any other CL API will generate a `CL_INVALID_EVENT` error.

## Errors

Returns a valid OpenCL event object and `errcode_ret` is set to CL_SUCCESS if the event object is created successfully. Otherwise, it returns a NULL value with one of the following error values returned in `errcode_ret`:

- CL_INVALID_CONTEXT if `context` is not a valid context or was not created from a GL context.
- CL_INVALID_GL_OBJECT if `sync` is not the name of a sync object in the GL share group associated with `context`.

## Specification

OpenCL Specification

## Also see

cl_khr_gl_event, clEnqueueAcquireGLObjects, clRetainEvent

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