CLCREATEFROMD3D11BUF(3clc)

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💖 CLCREATEFROMD3D11BUF(3clc) 💖

okay bestie, welcome to the OpenCL Manual, this one's the clCreateFromD3D11BUF(3clc) page and it's literally all about borrowing a Direct3D 11 buffer and letting OpenCL play with it. no cap.

✨ NAME ✨

clCreateFromD3D11BufferKHR — creates an OpenCL buffer object from a Direct3D 11 buffer. it's giving "two worlds, one buffer" 💅

cl_mem clCreateFromD3D11BufferKHR(cl_context context,
                                  cl_mem_flags flags,
                                  ID3D11Buffer *resource,
                                  cl_int *errcode_ret);

🎀 PARAMETERS 🎀

  • context — a valid OpenCL context, and it has to have been created from a Direct3D 11 device. no random contexts allowed, queen.
  • flags — a bit-field for usage info. it can be CL_MEM_READ_ONLY, CL_MEM_WRITE_ONLY, or CL_MEM_READ_WRITE. (there's a whole table in clCreateBuffer(3clc) if you want the deep lore 🍓)
  • resource — a pointer to the Direct3D 11 buffer you wanna share. that's the whole point, bestie.
  • errcode_ret — where the appropriate error code goes. if errcode_ret is NULL, then no error code comes back. it's giving "don't ask, don't tell" 🙈

🌸 NOTES 🌸

the size of the returned OpenCL buffer object is the same as the size of resource. periodt.

this call increments the internal Direct3D reference count on resource. and the internal Direct3D reference count on resource gets decremented when the OpenCL reference count on the returned OpenCL memory object drops to zero. it's a whole handshake, very mutual, very healthy relationship energy 🫶

so, general tea about sharing memory objects with Direct3D 11:

the goal of this extension is to provide interoperability between OpenCL and Direct3D 11. it's designed to function analogously to the OpenGL interoperability. if this extension is supported by an implementation, the string cl_khr_d3d11_sharing(3clc) will be present in the CL_PLATFORM_EXTENSIONS or CL_DEVICE_EXTENSIONS string described in the table of allowed values for param_name for clGetDeviceInfo(3clc). (iykyk 👑)

as currently proposed, the interfaces for this extension would be provided in cl_d3d11.h.

this section discusses OpenCL functions that allow applications to use Direct3D 11 resources as OpenCL memory objects. this allows efficient sharing of data between OpenCL and Direct3D 11 — lowkey the whole point. the OpenCL API may be used to execute kernels that read and/or write memory objects that are also Direct3D 11 resources. an OpenCL image object may be created from a Direct3D 11 texture resource. an OpenCL buffer object may be created from a Direct3D 11 buffer resource. and here's the rule, bestie: OpenCL memory objects may be created from Direct3D 11 objects if and only if the OpenCL context has been created from a Direct3D 11 device. no shortcuts. 💀

an OpenCL memory object created from a Direct3D 11 resource remains valid as long as the corresponding Direct3D 11 resource has not been deleted. if the Direct3D 11 resource is deleted through the Direct3D 11 API, subsequent use of the OpenCL memory object will result in undefined behavior, including but not limited to possible OpenCL errors, data corruption, and program termination. so like… don't. 😭

🚨 bestie heads up: deleting the D3D11 resource out from under the OpenCL object = undefined behavior, and that list includes data corruption and your program straight up dying. dramatic but true.

the successful creation of a cl_context against a Direct3D 11 device specified via the context create parameter CL_CONTEXT_D3D11_DEVICE_KHR will increment the internal Direct3D reference count on the specified Direct3D 11 device. the internal Direct3D reference count on that Direct3D 11 device will be decremented when the OpenCL reference count on the returned OpenCL context drops to zero. again: reciprocal. we love to see it ✨

the OpenCL context and corresponding command-queues are dependent on the existence of the Direct3D 11 device from which the OpenCL context was created. if the Direct3D 11 device is deleted through the Direct3D 11 API, subsequent use of the OpenCL context will result in undefined behavior, including but not limited to possible OpenCL errors, data corruption, and program termination.

properties of Direct3D 11 objects may be queried using clGetMemObjectInfo(3clc) and clGetImageInfo(3clc) with param_name CL_MEM_D3D11_RESOURCE_KHR and CL_IMAGE_D3D11_SUBRESOURCE_KHR as described for clGetImageInfo(3clc) and in the information below about accessing mapped regions of a memory object.

🦋 Accessing mapped regions of a memory object

this section describes the behavior of OpenCL commands that access mapped regions of a memory object.

the contents of the region of a memory object and associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) mapped for writing (i.e. CL_MAP_WRITE or CL_MAP_WRITE_INVALIDATE_REGION is set in map_flags argument to clEnqueueMapBuffer(3clc) or clEnqueueMapImage(3clc)) are considered to be undefined until this region is unmapped. so, undefined. fr fr.

multiple commands in command-queues can map a region or overlapping regions of a memory object and associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) for reading (i.e. map_flags = CL_MAP_READ). the contents of the regions of a memory object mapped for reading can also be read by kernels and other OpenCL commands (such as clEnqueueCopyBuffer(3clc)) executing on a device(s).

mapping (and unmapping) overlapped regions in a memory object and/or associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) for writing is an error and will result in CL_INVALID_OPERATION error returned by clEnqueueMapBuffer(3clc) or clEnqueueMapImage(3clc). not cute. 💅

if a memory object is currently mapped for writing, the application must ensure that the memory object is unmapped before any enqueued kernels or commands that read from or write to this memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin execution; otherwise the behavior is undefined.

if a memory object is currently mapped for reading, the application must ensure that the memory object is unmapped before any enqueued kernels or commands that write to this memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin execution; otherwise the behavior is undefined.

accessing the contents of the memory region referred to by the mapped pointer that has been unmapped is undefined. don't touch the ghost, bestie 🫣

the mapped pointer returned by clEnqueueMapBuffer(3clc) or clEnqueueMapImage(3clc) can be used as ptr argument value to clEnqueueReadBuffer(3clc), clEnqueueWriteBuffer(3clc), clEnqueueReadBufferRect(3clc), clEnqueueWriteBufferRect(3clc), clEnqueueReadImage(3clc), and clEnqueueWriteImage(3clc), provided the rules described above are adhered to. the rules. always the rules. 🌈

🔥 ERRORS 🔥

returns CL_SUCCESS 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. (bestie, that's not a context.)
  • CL_INVALID_VALUE if values specified in flags are not valid.
  • CL_INVALID_D3D11_RESOURCE_KHR if resource is not a Direct3D 11 buffer resource, if resource was created with the D3D11_USAGE flag D3D11_USAGE_IMMUTABLE, if a cl_mem from resource has already been created using clCreateFromD3D11BufferKHR, or if context was not created against the same Direct3D 11 device from which resource was created. so many ways to get this one wrong, honestly iconic 💀
  • CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

⭐ SPECIFICATION ⭐

OpenCL Specification[1]

💜 SEE ALSO 💜

🌟 AUTHORS 🌟

The Khronos Group

Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be
included in all copies or substantial portions of the Materials.

📚 NOTES 📚

  1. OpenCL Specification page 104, section 9.11.7.3 - Sharing Direct3D 11 Buffer Resources

and that's the whole page, bestie 🫶 big kisses from The Khronos Group, this doc is dated 01/14/2021, and it's the CLCREATEFROMD3D11BUF(3clc) girlies' official manual page. go share those buffers responsibly. slay 💅✨

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