General information about GL sharing follows.
The OpenCL specification in section 9.7 defines how to share data with
texture and buffer objects in a parallel OpenGL implementation, but does not
define how the association between an OpenCL context and an OpenGL context
or share group is established. This extension defines optional attributes to
OpenCL context creation routines which associate a GL context or share group
object with a newly created OpenCL context. If this extension is supported
by an implementation, the string "cl_khr_gl_sharing" will be present in the
CL_DEVICE_EXTENSIONS string described in the table of allowed values for
param_name for clGetDeviceInfo or in the
string described in the table of allowed values for param_name for
This section discusses OpenCL functions that allow applications to use OpenGL buffer, texture, and renderbuffer objects as OpenCL memory objects. This allows efficient sharing of data between OpenCL and OpenGL. The OpenCL API may be used to execute kernels that read and/or write memory objects that are also OpenGL objects.
An OpenCL image object may be created from an OpenGL texture or renderbuffer object. An OpenCL buffer object may be created from an OpenGL buffer object.
Any supported OpenGL object defined within the GL share group object, or the share group associated with the GL context from which the CL context is created, may be shared, with the exception of the default OpenGL objects (i.e. objects named zero), which may not be shared.
If the cl_khr_mipmap_image, extension is supported by the OpenCL device, the
cl_khr_gl_sharing extension adds support for creating a mip-mapped CL image from a mip-mapped GL texture.
To create a mip-mapped CL image from a mip-mapped GL texture, the miplevel argument to clCreateFromGLTexture, should be a negative value. If miplevel is a negative value then a CL mipmapped image object is created from a mipmapped GL texture object instead of a CL image object for a specific miplevel of a GL texture.
|For a detailed description of how the level of detail is computed, please refer to section 3.9.7 of the OpenGL 3.0 specification.
For more information, see the OpenCL Extension Specification at URL