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<div class="moz-text-flowed" style="font-family: -moz-fixed;
font-size: 14px;" lang="x-western">Hey everyone,
<br>
I played around a bit with OpenCL the past few days and want to
share my foundings here.
<br>
<br>
1) Nvidia GT 540M:
<br>
I compiled Blender with default settings, also for OpenCL. That
means only __KERNEL_SHADING__ and __MULTI_CLOSURE__ was enabled.
<br>
<br>
The compilation fails though: It does not like the "int segment =
~0" default.
<br>
<br>
:26679:87: error: C does not support default arguments
<br>
int shader, int object, int prim, float u, float v, float
t, float time, int segment = ~0)
<br>
<br>
I compiled without hair support and removed the segment parameter
to workaround this issue.
<br>
I tested with color_ramp.blend (SVN test repository) and Mix and
Add Shaders do not work. Only the first closure input is passed
through, the second gets ignored.
<br>
<br>
It seems to be related to __MULTI_CLOSURE__. When I recompile the
OpenCL kernel without it, mix and add shaders work fine.
<br>
<br>
2) Intel Core i7 2630QM
<br>
I wanted to test OpenCL on my Sandy Bridge Intel CPU, but the CPU
is not recognized. I of course changed device_opencl.cpp and
replaced all CL_DEVICE_TYPE_ parameters to CL_DEVICE_TYPE_ALL.
<br>
The issue is in the way Cycles detects OpenCL platforms as far as
I can see that. LuxMark 2.0 recognized both devices (nvidia GPU
and Intel CPU) fine.
<br>
<br>
I could not get it up and running, although I found that changing
the "platform_ids[]" index from 0 to 1 in lines 757 and 762 in
device_opencl.cpp, at least brings up the device inside of the
User Preferences. (the nvidia card disappears then though from
UserPrefs, yet it will still render with the GPU).
<br>
<br>
3) Intel Core i5-3570 with HD 2500 GPU
<br>
Intels Ivy Bridge CPUs now also support OpenCL on the GPU, so I
wanted to test that. Both devides (CPU and GPU) show up fine in
User Preferences (after CL_DEVICE_TYPE_ALL tweak) but the kernel
compile crashes. It starts, but after some time Blender just
closes. I could not debug that further.
<br>
<br>
Thanks for reading this.
<br>
<br>
Brecht: Please don't see this as a real bug report, I know OpenCL
development is on hold but it's interesting to keep an eye on it
and maybe some information here is helpful.
<br>
<br>
All tests done on Windows 7 x64.
<br>
<br>
Best regards,
<br>
Thomas
</div>
<pre class="moz-signature" cols="72">--
Thomas Dinges
Blender Developer, Artist and Musician
<a class="moz-txt-link-abbreviated" href="http://www.dingto.org">www.dingto.org</a></pre>
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