clCreateFromGLBuffer
clCreateFromGLBuffer
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clCreateFromGLBuffer Creates an OpenCL buffer object from an OpenGL buffer object.

##

cl_mem `clCreateFromGLBuffer` cl_context context cl_mem_flags flags GLuintbufobj cl_int* errcode_ret

## Parameters

`context`

  A valid OpenCL context created from an OpenGL context.

`flags`

  A bit-field that is used to specify usage information. Refer to the table for clCreateBuffer for a description of `flags`. Only `CL_MEM_READ_ONLY`, `CL_MEM_WRITE_ONLY` and `CL_MEM_READ_WRITE` values specified in the table at clCreateBuffer can be used.

`bufobj`

  The name of a GL buffer object. The data store of the GL buffer object must have have been previously created by calling OpenGL function `glBufferData`, although its contents need not be initialized. The size of the data store will be used to determine the size of the CL buffer object.

`errcode_ret`

  Returns an appropriate error code as described below. If `errcode_ret` is NULL, no error code is returned.

## Description

The size of the GL buffer object data store at the time `clCreateFromGLBuffer` is called will be used as the size of buffer object returned by `clCreateFromGLBuffer`. If the state of a GL buffer object is modified through the GL API (e.g. `glBufferData`) while there exists a corresponding CL buffer object, subsequent use of the CL buffer object will result in undefined behavior.

The clRetainMemObject and clReleaseMemObject functions can be used to retain and release the buffer object.

The CL buffer object created using `clCreateFromGLBuffer` can also be used to create a CL 1D image buffer object

## Errors

Returns a valid non-zero OpenCL buffer object and `errcode_ret` is set to CL_SUCCESS if the buffer 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_VALUE if values specified in `flags` are not valid.
- CL_INVALID_GL_OBJECT if `bufobj` is not a GL buffer object or is a GL buffer object but does not have an existing data store e or the size of the buffer is 0. .
- CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.
- CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

## Specification

OpenCL Specification

## Also see

cl_khr_gl_sharing, clCreateBuffer, clReleaseMemObject, clRetainMemObject

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