CPU: Intel Core i5
RAN: 6 Gb DDR3 RAM
GPU: Asus ENGTS450 DirectCU (RAM 1 Gb GDDR5)
OS: Windows 7 Ultimate x64
Blender: official 2.65a release
The displacement doesn't work with GPU rendering, either during preview, either for rendering.
It works fine with various previous builds wich was stable for me (various 2.6 builds from graphicall).
I tried also the 'normal' input node for the shaders, but the displacement works only with OSL enabled (so with CPU).
Also, sometimes the shaders doesn't works (with GPU rendering) and I see a diffuse violet shader (like when an image texture is missing), and again everything works well if I switch to OSL (even if I swith to CPU but without enabling OSL).
Last, sometimes Blender crashes during GPU rendering (also in preview) causing a black screen and a message from nVidia driver wich says that the OpenGL has been restarted.
I'm talking about simple scenes with a cube with a 1024 texture, sky texture and sometimes AO.
Please always attach a .blend file and exact steps for us to redo the problem. If something doesn't work 'sometimes' that's not enough information for us to investigate, it really needs to be exact.
Note that issues with features available after enabling Experimental are not considered bugs:
everything works fine on provious build, the problem started with 2.65 and 2.65a. I wrote 'sometimes' because I don't understood what causes the crash, however it is impossible to work with.
I will prepare a simple .blend file and attach it.
Carlo, we can not fix occasional issues, we need to know exact steps of reproducing the issue. Please provide sample .blend file, also please test builds from http://builder.blender.org/download/ where the issue could have been resolved. It could also worth testing on system console for possible error prints.
Thank you Sergey. I also tried the last build (r53307) but the main problem remains the same.
Here's the blend file: http://www.pasteall.org/blend/18378 (CC-BY-NC)
The displacement works only with OSL enabled; with OSL disabled and with GPI compute, displacement doesn't works.
On previous builds it used to work (without the bump node, of course, so using output displacement and not shader's normal inputs), but now previous builds crashes if I choose rendered view or hit F12 (either CPU or GPU).
The console also crashes and I can't read what causes the crash.
How can I generate a log?
I isolated the problem: http://www.pasteall.org/pic/42355
Cycles is able to handle this only with OSL (it's a 4K png); the displacement doesn't work and sometimes I see violet if I connect this texture to the color input of any shader.
I converted the map to jpg and everything works fine even without OSL enabled.
I hope this discover will help the development.
Fixed a crash now enabling "True" displacement on the mesh in this .blend file. I'm not sure if that's what you were testing, it was set to Bump in the .blend file so it's not clear to me if that is crashing for you too.
Thank you Bretch. I was trying different things, also true displacement (in fact as you can see, there's a subdivision surfaces modifier disabled and with subdivisions sets to 0; I was trying to heavily subdivide the mesh to achieve a true displacement but I have a lot of testing to do also comparing with the 'displace' modifier).
However I noticed that sometimes Cycles didn't recognize PNG files without OSL (I attached the file http://www.pasteall.org/pic/42355) so I resolved switching to JPG (but in this case the JPG is much larger in size and lower in quality).
Did you have an idea on what causes this?
I am closing this now, Displacement is not officially supported yet in Cycles.
In regards to the png issue, png files work fine for me (Windows and Linux) with OSL and without, not sure whats going on here.
If you can reproduce the PNG issue with a new build from builder.blender.org and can provide an example blend file, feel free to open a new report with the issue. :)