Bug: block with render mesh effect and material set to object parent

Hi, I just spent too much time trying to figure out what I was doing wrong when trying to set different materials to the same block definition but it turns out nothing - it’s just a bug.

To trigger it, this combination must happen:

  1. Have an object inside a block, the object’s material set to “Use Object Parent” and with a render mesh effect (eg. Edge Softening, Thinckening etc.) applied.
  2. Exit the block and either directly apply a custom material directly onto the block object or set it to “Use Layer Material” if the block is on a layer with a custom material.
  3. Expected behavior: the object should have the custom material in Rendered viewport. Instead, Default material is shown.

If you edit the block definition and turn off all mesh effects and exit the block, then material is suddenly applied correctly.

See below: Blue cube has material applied to the block, orange cube to its layer. The two white cubes behind them are set up in the exact same way but with Edge softening turned on:

Same file opened in Rhino 6, working as expected:

block-material-parent-render-mesh-effects-bug.3dm (380.1 KB)

Edit: Rhino version 8.9.24177.13001, 2024-06-25 in Windows 11

Ok, it seems this is purely visual and only affecting Rendered display mode. Raytraced display mode is fine and V-ray also renders it correctly.

Edit: No wait, this is Rhino render (Cycles) - all correct:

And this V-ray - only the layer asigned material is correct:

Edit2: And just for comparison, same version of V-ray (6.20.04) but run from Rhino 6:

Hi @SimonR ,

Thanks for this report. I’ve filed this as https://mcneel.myjetbrains.com/youtrack/issue/RH-82840 for the developers.

Thanks. I also just edited my last post, showing that when rendering via V-ray, the bug manifests itself as well but only partially.

Thanks, I saw that and added more info to the bug report. I’m not sure if that is something the dev can address, they’ll need to weigh in.

Well, Vray renders it correctly in Rhino 6 so I was thinking perhaps they can but I know nothing about what’s under the hood.