Does anyone know why Dynamic Animations (like ponytails) would explode like crazy in the first two frames of a render but then function normally after? At first I thought it might be collision related, but I went ahead and deleted all the collision spheres and the problem still happens. It only seems to happen when rendering, not in Physics or Blueprint previews or in-game. Here’s a small video of the issue I am having:
Has to be a result of the PHAT asset settings.
OR - something caused by CHAOS maybe.
either way, without collision within the phat asset, the hair wouldn’t bobble the way it’s bobbling in the video… so what collisions did you delete?
To test the PHAT try disabling gravity and toggling the chain to see if anything reacts oddly or spazzes out - preferably after loading the same pose as the video, or you may never find the problem.
Also, as almost always, it’s not the only thing in the scene that isn’t initialized.
The fire, the candle, and any other physically based thing is probably delayed.
Generally, I start recording only after the scene has “spun up”.
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I deleted the collision between every single capsule and sphere just to be sure. It still spazzes out and explodes on the first frame.
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I tried disabling gravity on the hair, it definitely still spazzes out on the first frame, just doesn’t fall towards the ground afterwards as expected.
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I generally have 10 frame handles at the start and end of my sequences, just in this case the effects of the explosive hair are lasting almost 100 frames before it settles down and behaves normally again. I suppose worst case scenario I can give the sequence 100 frames for the hair to calm down and just cut that out in post.
The thing that is strange is the hair was working fine yesterday. I have a suspicion the new version of Unreal (4.26.2) is in some way related to this problem since I finally updated to it last night and the problem started when I fired up the project today.
Depends on what version you came from, but it is possible, if not very likely.
So the phat asset is not doing this at all when you start simulating without gravity?
No, it still explodes on the first frame even with gravity disabled.
When looking at the phat asset in Persona directly?
If thats the case the issue has to be one of the collisions - or bone orientation constraints.
just updating for posterity:
I was having same issue where my mesh explodes in PIE but looks correct in the anim blueprint preview.
Turns out I had entered a crazy value into the “use wind” parameter. So just double check that.
More normally, explosions like that are caused by having an object attached (weapon?) Which collides with the character capusule or the mesh phat.
Persona (the standard view of a character bp visual, and also the PHAT asset simulation view) doesn’t really take into account game-time collisions.
i thougth that anim dynamics only interacted with teh special constraints that you create just for them?
in my project it does not appear that they interact at all with PHAT or any other collisions.
the docs say this (last line):
Anim dynamics specifically do not have anything but self collisions - so that docs bit seems incorrect. They used to check and correct for the character’s capsules / bounce against the underlying PHAT.
Other phat things can (depends on settings) respond to nearly all collisions.
Now a days instead of doing anymdynamics you would probably do a control rig solver to also provide some world interaction to things - like say a lara croft like pony tail for one.
It’s no longer just about anymdynamics really, if you consider that.
But even if it were, as I said, it used to collide against the main mesh PHAT asset as far as i remeber from the last time I set this us (before this topic was made).
oh, makes sense. i didnt know about control rig solvers, will look into that. setting up the constraints for anim dynamics was kind of a pain, would be nice if it just collided with same PHAT that cloth sim uses