C4DtoA no material preview (black square with red around)

[Anonymous]

Hello,

I don't know why but since I updated arnold to 2.5.0 and now 2.5.1 all my materials previews turn to black with a red contour but my renders are ok

Any thought ?

Thanks

[peter.horvath6V6K3]

That's odd, there were no changes related to material previews, as far as I recall. The black preview with red frame indicates a render error, a typical issue is a missing texture in the shader network. We had no similar reports recently, so may be something local. Maybe the preview scenes got corrupted somehow? What if you create a new scene, are the previews work there?

[Anonymous]

Hello Peter,

If I create a new scene, the material preview is ok

In this corrupted scene there's only few materials in black but after a while evreything turn to black

Not all materials have texture and I have checked the path in the Asset/tx manager and all links are ok

Is there a way to recover these material preview ?

Thanks

[peter.horvath6V6K3]

If it works in a new scene than the preview scenes are not corrupted. I'm not sure what's going on, I have not heard of previews turning to black on-the-fly before. Sounds like the issue is specific to this one scene. Can you send me the scene, I wonder if I can reproduce the issue with it?

[Anonymous]

Here is the corrupted materials library

arnold-corrupted-mat.zip

[Anonymous]

When I import them they are black

[peter.horvath6V6K3]

If I change a parameter or open the network editor, which triggers an update, then the previews render fine.

[alex.altmann]

I've had this happen as well. Double click on the shader in question. When the window opens, right click on the black square with red outline and select either a new size or preview type. It recreates the preview.

[alex.altmann]

Was playing with this a little more. Fastest way is to select all of the shaders with the black box, then right click and select "Render Materials". Don't have to do them individually then.

[Anonymous]

Alex and peter, thanks for your help

I have already done this with my corrupted scene and it was not working so peter you are right, it's a problem with the local scene

Here it is and if I try to Render Materials as Alex said, it's not working at all, materials stay black

arnold-corrupted-scene.zip

[Anonymous]

Ok finally I have found a solution to recover my corrupted materials:

1. create a new scene

2. merge the corrupted scene

3. right clic on a black square of death an choose "Render All Materials"

4. some materials will stay black because of the path of the texture not good

5. to fix this go to plugins>c4dtoA>Asset/tx Manager

6. in the manager clic "select missing" and clic "relink" button next to it

7. choose texture location and that's all, everything is fixed !!

Thank to Peter and Alex for their help !

[peter.horvath6V6K3]

I'm glad you could finally solve it. I can reproduce the issue in your scene and I'm trying to figure out what's going on and fix this.

[peter.horvath6V6K3]

OK, got it. At least on my system the previews fail, because the color manager in the scene is set to OCIO and the config file is defined by the OCIO environment variable ($OCIO) which is not set on my system.

Would be nice to report preview render errors in the console, trying to add this to the next release.

[Anonymous]

Well done peter !

Would be nice to report preview render errors in the console, trying to add this to the next release.

on this site or with c4d application ?

what should I do exactly ?

[peter.horvath6V6K3]

You don't have to do anything. I will update the code to display the error message in the console, so users will have a better understanding of why the material preview is not rendering.

[Anonymous]

ah ok I understand, yes it's a good idea to inform users