This extension enables the funciton clCreateEventFromGLsyncKHR.
This extension allows creating OpenCL event objects linked to OpenGL fence sync objects,
potentially improving efficiency of sharing images and buffers between the two APIs. The
companion GL_ARB_cl_event
OpenGL extension provides the complementary functionality of creating an OpenGL sync object from an OpenCL event object.
This extension modifies the behavior of clEnqueueAcquireGLObjects and clEnqueueReleaseGLObjects to implicitly guarantee synchronization with an OpenGL context bound in the same thread as the OpenCL context.
If this extension is supported by an implementation, the string cl_khr_gl_event
will be present in the CL_PLATFORM_EXTENSIONS or CL_DEVICE_EXTENSIONS string described in the table of param_name
values for clGetDeviceInfo.
If the cl_khr_gl_event
extension is supported, then the OpenCL implementation will ensure that any such pending OpenGL operations are complete for an OpenGL context bound to the same thread as the OpenCL context. This is referred to as implicit synchronization
.
If the cl_khr_gl_event
extension is supported and the OpenGL context in question supports
fence sync objects, completion of OpenGL commands may also be determined by placing a GL fence command after
those commands using glFenceSync
, creating an event from the resulting GL sync object
using clCreateEventFromGLsyncKHR, and determining completion
of that event object via clEnqueueAcquireGLObjects. This
method may be considerably more efficient than calling glFinish
, and is referred to as
explicit synchronization
. Explicit synchronization is most useful when an OpenGL context
bound to another thread is accessing the memory objects.
If the cl_khr_gl_event
extension is not supported, completion of OpenGL commands may be
determined by issuing and waiting for completion of a glFinish
command on all OpenGL
contexts with pending references to these objects. Some implementations may offer other efficient synchronization
methods. If such methods exist they will be described in platform-specific documentation.
Note that no synchronization method other than glFinish
is portable between all OpenGL
implementations and all OpenCL implementations. While this is the only way to ensure completion that is portable
to all platforms, glFinish
is an expensive operation and its use should be avoided if the
cl_khr_gl_event
extension is supported on a platform.
When this extension is enabled, the following functions are also affected:
param_name
is CL_EVENT_COMMAND_TYPE.