[Bf-cycles] Apple OpenCL and Cycles

Marcio Andrade migueletto at yahoo.com
Mon Dec 17 16:33:10 CET 2012

You have to modify Blender source code and make a custom build.
Inside device_opencl.cpp, I changed a few lines like this:

clGetDeviceIDs(cpPlatform, CL_DEVICE_TYPE_GPU|CL_DEVICE_TYPE_ACCELERATOR, 0, NULL, &num_devices)))

To include also CL_DEVICE_TYPE_CPU in the bitfield on the second parameter.


De: Nazim Mer <nazim.mer at gmail.com>
Para: bf-cycles at blender.org 
Enviadas: Segunda-feira, 17 de Dezembro de 2012 13:29
Assunto: Re: [Bf-cycles] Apple OpenCL and Cycles

what do i need to do to enable opencl on my cpu, ive already got AMD APP SDK 2.8 installed.
can u 'BRECHT n team' enable this for everyone
in slg3 opencl is slightly faster than its nonopencl counter part
seasons greatings 
nazim mer
On Dec 17, 2012 2:35 PM, "Brecht Van Lommel" <brechtvanlommel at pandora.be> wrote:

>I believe the main problem with AMD is a hardware limitation that we
>are running into, so using the Apple compiler would not help solving
>that particular problem. But I can't be sure, the compiler is not
>outputting particularly useful information when it fails. Also note
>that the OpenCL kernel currently has many features disabled, they can
>be enabled in kernel_types.h.
>I don't think anyone is looking into OpenCL on Apple at the moment. I
>didn't test the latest compiler, but my experience has been that
>OpenCL on the CPU is not a problem, it's when compiling for the GPU
>that the problems start. Regarding performance it's probably not going
>to be great if you get it working, each graphics card tends to have
>some specific things that need to be optimized, so it wouldn't be
>possible to make a judgement on that immediately.
>On Mon, Dec 17, 2012 at 1:57 PM, Marcio Andrade <migueletto at yahoo.com> wrote:
>> Hello,
>> I read that OpenCL development on Cycles is on hold, mainly because of compiler/driver problems in the AMD SDK. I have been doing some experiments with OpenCL on a Mac, and so far I did not encounter thouse kind of problems. After making some small changes to the kernel (basically enabling some defines that were commented out in kernel_types.h and fixing one compile error), I gave it a try.
>> Compilation is fast and does not give memory errors. On my system the kernel is compiled in under 5 seconds. My Mac has a Intel HD 3000 GPU, which does not support OpenCL, so in order to make these tests I enabled OpenCL on the CPU (a small change to device_opencl.cpp). When I run the kernel in Blender, rendering time is close to the normal render using CPU, which is expected, since OpenCL Kernel on CPU should be close to the C++ Kernel on CPU.
>> Apple is the original author of OpenCL, and OpenCL support on Macs seems to be pretty decent (no need to install anything, it is already bundled). So, is there anyone else trying Cycles/OpenCL on Apple hardware ? I would like to know how OpenCL performs on a Mac with a true GPU, to see if its worth pursuing this direction.
>> Regards,
>> migueletto
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