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Issue using two spring modifiers

Posted: Mon Mar 07, 2022 8:14 am
by gsedory99
Hi,

I'm trying to use two spring modifiers. The first one is on a scale transform modifier and then later on in the node tree I have a second falloff and a rotation transform modifier. When I try to add a spring modifier after that to modify the rotation, the scene gets all wacky and does things I'm unable to explain. I tried deleting all the attributes that the previous MOPs nodes created before adding the falloff, transform and spring modifiers the second time but that didn't seem to work either. Any thoughts would be great. Really appreciate the help.

Re: Issue using two spring modifiers

Posted: Mon Mar 07, 2022 8:19 am
by toadstorm
Any chance you could post a quick hip file that demonstrates the problem?

Re: Issue using two spring modifiers

Posted: Mon Mar 07, 2022 9:42 am
by gsedory99
Sure this is a quick simple example. Just adding a second falloff as mops_falloff2 and a transform modifier for rotation to utilize it. Then I want to modify that second animation with a spring modifier and I'm having trouble doing that.

Thanks!

https://we.tl/t-joivxYWmnF

Re: Issue using two spring modifiers

Posted: Mon Mar 07, 2022 9:45 am
by gsedory99
Sorry the link didn't work there, here is the hip file.

Re: Issue using two spring modifiers

Posted: Mon Mar 07, 2022 10:39 am
by toadstorm
The Spring Modifier is freaking out in this case because on the first frame of the simulation, there aren't any objects due to the Blast SOP deleting all points greater than the falloff threshold. If you move that Blast to after the second Spring Modifier, the scene should work normally.

Spring Modifier internally is using a Solver SOP, which means its conditions are locked on the first frame of simulation... it's not adding new objects over time. It's something I can look into to see if it's possible to merge in new objects over time. If I can get it working without too much of a performance hit, I'll add it to a future release.

Re: Issue using two spring modifiers

Posted: Mon Mar 07, 2022 11:16 am
by gsedory99
awesome! Thanks for the help with this. You are a genius. Truly love what you're doing with this. Primarily C4D user here and I'm working hard to try and see if I can do most of my C4D Mograph-like work through houdini+MOPs. This helps a lot.

Re: Issue using two spring modifiers

Posted: Mon Mar 07, 2022 11:20 am
by toadstorm
Happy to help! If you have any other comments or suggestions about MOPs, feel free to reach out to me here, by email, or on the MOPs Discord.