Weird bug with Particle Instance Modifier
Open, Needs TriagePublic

Description

System Information
Win 10 x64, nVidia GTX 1080Ti

Blender Version
Broken: All
Worked: (optional)

Short description of error
I have a very weird bug with the Particle Instance Modifier. In the OpenGL viewport, rendered view and when rendering in the GUI (F12) everything renders fine, but when rendering via command line or on the farm (with cgru, i.e. a farm software rendering with the command line), the instances are located at the wrong place.

I use a very simple hair emitter to instance meshes along the strands using the "Create along Paths" option. It works very nicely and interactively in the viewport but fails in a very weird way as soon as I send my scene on the farm. I attached a simplified version of the scene and hope it can be fixed.

Exact steps for others to reproduce the error

  • Load this blend file:

  • Press F12 to render. It looks like this:

  • Now call the same render via command line. It should work like this, you will have to change the paths:
blender -b "E:\Instance_Bug_v01.blend" -o "E:\Instance_Bug.#" -s 1 -e 1 -a"
  • This is the result:

  • All the instances now start from the origin of the scene (at least in this example). And they also have weird velocity vectors.

P.S.: Here are the motion vectors when rendering with the command line. There is no animation or deformation on these instances whatsoever, when rendering in the GUI the motion vector pass is totally neutral / empty:

Details

Type
Bug

Found two other bugs already while trying to confirm yours… :/

Thanks, I actually had render crashes in this project, but it was too weird to reproduce easily. Also I am currently too swamped with work. Hopefully you can kill all these bugs ;)