dForce always jitters, any ideas?

benniewoodell

Hello! So I've been doing this shot for an animated commission and I have the guy lifting up a piece of paper. I added dForce to the paper so it would move a little bit. I like how the paper itself moves when it's lifted up, but as you can see in the video, when he's holding it still, it's flapping as if there's a ton of wind blowing on it and I don't have any wind nodes. I find a lot of times this happens when I use dForce on hair and clothing as well when a character is standing still and I have no clue what setting it is to fix it. I watched the dForce tutorial from this past weekend hoping to learn something to help and sadly nothing for this came from that. I've read the dForce start here thread and turned the iterations up to 64 thinking that might have worked, but it did nothing. I did turn stiffness all the way up and the paper exploded on me for some reason. I'm posting a link to the video example here, if anyone knows anything about dForce and knows what I can do to fix this, I will be so, so very much appreciative as it's something that's been a thorn in my side for awhile now but since this is for an actual job, I can't just let it slide. Thank you! 

https://www.youtube.com/watch?v=wQhqmlUu2s8

Richard Haseltine

I believe it's likely to be the stiffness that causes the issue - dForce works by treating each edge of the geometry as a spring and it iterates over the springs trying to diffuse the energy they conatin due to the movement of the item and the effect of gravity (or wind when present). The more resistant the springs are the harder it is to actually dump energy, in extreme cases leading to explosions. In this case, all I can think of is reducing the dynamic strength once the paper is in place, but that's tricky as - without using a proxy node linked to the material property - it isn't animatable.

benniewoodell

Okay, so I got it not perfect but better. I watched the spring dynamics video from WP Guru and when he went through the settings for stiffness and dampness, it showed how they work with the waveform and when dampness was jacked up all the way, there was little movement. So that got me thinking what if I did that here? So I put the main dampness to a hundred percent and the paper still moves a little bit, but not nearly as noticable in the clip above to a point where I'm happy with it! Thanks for the expaination of how it works Richard, I appreciate it :)