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Maniphest T40442

Subordinated particles missing
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Description

System Information
Win7/64

Blender Version
blender-2.70-06a05e4-win64

Short description of error
If a particle system renders group objects, and the group objects also have a particle system, the latter are not rendered with the first particle system.

Exact steps for others to reproduce the error
Open

NestedParticles.blend164 KBDownload

The selected object ("Trunk") has a particle system. Particles are rendered group objects from group "Group". The three mesh objects to the right belong to that group. Each of them has a particle system, too.
Problem: Looking at the tree only, the trunk's particles are rendered but the subordinated particles are missing.

Maybe you say it's "not supported" but I added the particle system for a reason, not for being ignored.

Thank you in advance.

Event Timeline

Willi (willi) created this task.May 30 2014, 3:09 PM
Willi (willi) raised the priority of this task from to 90.
Willi (willi) updated the task description. (Show Details)
Willi (willi) added a project: BF Blender.
Willi (willi) edited a custom field.
Willi (willi) added a subscriber: Willi (willi).
Willi (willi) added a comment.May 30 2014, 3:36 PM

I just see warnings in the console about a dependency cycle. I will recheck this...

Willi (willi) added a comment.May 30 2014, 3:58 PM

Ok, after fixing this, the problem stays the same: The arm's in the middle emit the twigs to the right, and the trunk emits the arm's in the middle, but not the subordinated twigs. Not in the viewport and not for rendering.

corrected file:

NestedParticles2.blend169 KBDownload

Lukas Tönne (lukastoenne) changed the task status from Unknown Status to Unknown Status.Jun 1 2014, 3:11 PM
Lukas Tönne (lukastoenne) claimed this task.

This is not a bug, but a deliberate limitation: Only groups, vertex and face duplis support nested duplis.

There are a couple of reasons for this:

  • It's very easy to create rapidly exploding numbers of duplis with nesting. This alone would be a bad excuse, but it has to be considered (safety limits on instances would help).
  • The dependency graph has serious issues with duplis, anything beyond a single layer is risky. Detecting cyclic dependencies could be tricky.
  • Particle systems with duplis actually create an inverted dependency to work around a design mistake in Blender Internal (yes, it makes me want to scream too ...)
  • Blender Internal itself has a number of builtin assumptions about duplis that can easily fail with unforeseen consequences if anything is changed there.

Replacing particles, depsgraph and Blender Internal altogether would help here ;P
Sorry, sarcasm is the only answer i have at this point.

Willi (willi) added a comment.Jun 2 2014, 12:30 PM

In short: *sigh* .... Ok, I understand. :-)
Thank you for your time in any case - and good luck with redesign from scratch in all areas! ;)