Forums Technical Discussion Moving POP source w/ animated SOP; collision issues

Moving POP source w/ animated SOP; collision issues

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AkkiSan
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I animated a grid with a wavelike motion and
dropped particles on it.

As long as I don't move the POP source everything is fine.

If I move the source on the object level, most of the
particles directly go through the grid, but if I move
“the wave” to the opposite direction instead, effectively
creating the same scene, everything is fine.

When I move the POP source inside the geo-node (a grid),
also everything is working as expected.

I quite often run into this behaviour, so I assume that I
indeed am missing a fundamental thing in Houdini.

Could anyone please clarify or explain what's going on?


Thanks
AS

Attachments:
POPonWaves.mp4 (2.2 MB)
POPonWaves_1.png (187.2 KB)
POPonWaves_2.png (302.2 KB)
POPonWaves_3.png (324.6 KB)
POPonWaves_4.png (32.9 KB)
POPonWaves_5.png (45.0 KB)

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anon_user_09389530
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It works fine for me, could you provide the scene, please.
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https://houdininotes.ivanlarinin.com/ [houdininotes.ivanlarinin.com]
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AkkiSan
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Not mentioned above, but I of course also tried playing with all the particle- and simulation settings,
as well as a more dense grid, but in fact nothing changes.

Test scene attached.
I would be very grateful if anyone could take a look at this.


Thanks
AS

Attachments:
POP_OnMovingObj_02_Mantra.hiplc (430.8 KB)

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anon_user_09389530
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Not sure why exactly this happens. My guess that it's not recommended to move your geo node with the dop network inside it. it's probably smth wrong with the transformation spaces calculation. I tried to split it using “object merge” into separate geometry nodes (with the dop network in a separate geo) and it works great.
I contribute to the beauty of this world
https://houdininotes.ivanlarinin.com/ [houdininotes.ivanlarinin.com]
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AkkiSan
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It probably is a feature, not a bug

Beside this problem and after some more tests in other scenes, which don't even work without animating anything,
I begin to think that particles just cannot be used this way.

But I still have a general problem with understanding all the problems that occur whenever an object
is translated on the scene level.

On to more testing, testing, testing …


Thanks
AS
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