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I am trying to animate a motion graphics animation with a somewhat complex setup: I use an object (object A) with a hair particle system on it as an instance of another object's (object B) hair particle system via the particle instance modifier. Object B also has animated displacement.

Now when I render the animation (either to a series of PNGs or directly to MP4) the location of object B's particles (meaning instances of object A) don't follow the displacement of object B. My modifier order on object B is displacement first and then the particle system, so I'm guessing it should work.

Interestingly, when I render all images / the entire video in one rush this issue arises but when I render a single frame, then move the cursor in the timeline to another frame and render this single frame again, everything works as expected.

Therefore this issue seems rather technical to me so any suggestion is welcome. In case more info is needed I will gladly provide it.

I created a blend file reduced to the problem that can be accessed here:

What it should look like - or rather: what it does look like when one frame is rendered separately: Everything is fine - the particles stay on the surface of the deformed Suzanne.

Depiction of successful render

What it looks like a few frames into the animation when I render all frames in one rush: Notice how the blue particles don't follow the topology of the red object.

Depiction of failed Render

For context I'm using this setup as a workaround to use displacement on metaballs: The hair particle system on object A is rendered as metaballs objects so there are a few of them merging into another, giving the illusion of fake-displacement so they get more of a weird blob shape than their natural, strictly spherical shape. Meaning one instance of object A is supposed to represent one metaball (even though it is actually multiple). Object B with its hair particle system is used to have a bunch of these "fake-metaballs" swirling through my scene. Any advice on how else to simulate displacement on metaballs is also welcome.

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  • $\begingroup$ please add screenshots so we know and can visualize what you are talking about. Text is nice - but one good image is more worth than 1000 words...or add your blend file. $\endgroup$
    – Chris
    Jun 30, 2021 at 13:11
  • $\begingroup$ @Chris thanks for t he advice. I added screenshots and the blend file $\endgroup$
    – Nigelino
    Jun 30, 2021 at 13:51
  • $\begingroup$ i still have problems to understand what your goal is. Do you want a metaball which is "kind of" wobbling? $\endgroup$
    – Chris
    Jun 30, 2021 at 14:09
  • $\begingroup$ @Chris Yes if there is a solution to get a wobbly metaball that can further be used as a instance in a particle system that would be my ultimate goal! What I described above is my attempt of a workaround since metaballs can't use modifiers. $\endgroup$
    – Nigelino
    Jun 30, 2021 at 14:28
  • $\begingroup$ @Nigelino not yet sure, but one clue is that all the sphere disappear if I disable "dead" instances.... $\endgroup$
    – james_t
    Jun 30, 2021 at 17:03

1 Answer 1

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Change the Physics Type to "Emitter", Physics Type to "None", and the instances now follow the vertices of the "parent". I'm going to claim blind luck and allow the cognoscenti in this forum to explain.

your file with my edits:

At frame 30: enter image description here

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  • $\begingroup$ thank you for your answer! :) $\endgroup$
    – Nigelino
    Jun 30, 2021 at 17:57
  • $\begingroup$ @Nigelino -- It would help my reputation (points) if you ACCEPT this post as an ANSWER. $\endgroup$
    – james_t
    Jul 1, 2021 at 16:32

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