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Cycles blackbody shader-node doesn't look the same with CPU, OSL and GPU.
Closed, ResolvedPublic


System Information
Windows 10 2xGTX960

Blender Version
Broken: 2.78RC1 0e5089c

Short description of error
Cycles blackbody shader-node doesn't look the same with CPU, OSL and GPU.
OSL and GPU have proper color range, but CPU without osl clamps values and makes weird pink color after that.

Exact steps for others to reproduce the error

  1. Select default Cube and go to material nodes
  2. Apply following nodes to the material Gradient Texture-->Multiply (5000)-->Blackbody-->Emission-->Material Output
  3. Switch render engine between CPU, GPU and OSL


Event Timeline

Sergey Sharybin (sergey) lowered the priority of this task from 90 to 30.Sep 5 2016, 3:39 PM

I can't reproduce the issue neither on Windows 10 nor on Linux Debian stable.

Does it happen for both viewport and final renders?

Can you try following:

  • Set debug value (shortcut is Ctrl-Alt-D) to 256.
  • This will enable some "secret" Debug panel in the Render settings.
  • See if disabling SSE/AVX options makes a difference on the error.
  • Please note that changing those options does not re-trigger viewport update, so you'll have to do it manually after tweaking any settings there.

Final and preview renders.

Ok found which causes it. It's happening on win10 if AVX2 is on.

Here screenshots how the blackbody looks like when it's not working correctly:

And correct one:

Bastien Montagne (mont29) raised the priority of this task from 30 to Normal.Sep 16 2016, 5:19 PM
Sergey Sharybin (sergey) triaged this task as 30 priority.Feb 3 2017, 4:40 PM

Doesn't happen on Linux..

Does it happen with latest builds from Does it happen with both msvc2013 and msvc2015 builds?

Using latest buildbot builds ( 9f67367 ) it only happens to the AVX2 kernel

2013_x64 - Bad
2013_x86 - OK
2015 X64 - OK
2015 X86 - Cycles is broken due to codegen bug, can't test