Vellum - timescale and constraint behavior

   267   5   0
User Avatar
Member
4 posts
Joined: Nov. 2024
Offline
I'm doing a vellum cloth sim on an animated character, which is already coming in slow motion. My sim ultimately also needs to feel slow motion to match this animation.

I set up the dynamics and constraints with the default timescale of 1 and 5 substeps. It's all working great until I reduced the timescale to 0.1 to get that slow motion feel to the sim. Now the cloth doesn't follow the animation closely enough, it just balloons out in places where the attach to geometry constraint or the pin to target constraint should be keeping it closely tied to the animation/character. Is there anything on the constraints or in the solver that I need to adjust to make the vellum constraints (specifically these 2 constraints, pin to target and attach to geometry) work similarly at a lower timescale? Checking the stress values shows that they are under more stress and the timescale is lowered, which is the opposite of what I would expect to happen

I wish I could just slow down the sim post sim but it will no longer track with my animated geometry that it needs to follow and environment collisions.

Any ideas? Thank you!
User Avatar
Member
8784 posts
Joined: July 2007
Offline
It's hard to say without seeing the scene, but make sure your character is moving smoothly between frames, either live deformed or interpolated between frames, otherwise it may be difficult for geo to catch up with constraints specially when using substeps, but of course it can be a different issue
Tomas Slancik
FX Supervisor
Method Studios, NY
User Avatar
Member
7 posts
Joined: Nov. 2024
Offline
Try increasing the sub steps to around 10 when reducing the timescale to 0.1. This can help improve the cloth simulation and keep it tight to the character. Also, adjust the stiffness or damping settings on the constraints like "Pin to Target" to avoid the cloth ballooning out. This should help the cloth match the animation more accurately in slow motion.
User Avatar
Member
4 posts
Joined: Nov. 2024
Offline
tamte
It's hard to say without seeing the scene, but make sure your character is moving smoothly between frames, either live deformed or interpolated between frames, otherwise it may be difficult for geo to catch up with constraints specially when using substeps, but of course it can be a different issue

Thank you Tomas! Yes the character and collisions are both interpolated between frames, I should've mentioned that in my post. I will try to submit an example of my issue soon.
User Avatar
Member
4 posts
Joined: Nov. 2024
Offline
JamesEdward
Try increasing the sub steps to around 10 when reducing the timescale to 0.1. This can help improve the cloth simulation and keep it tight to the character. Also, adjust the stiffness or damping settings on the constraints like "Pin to Target" to avoid the cloth ballooning out. This should help the cloth match the animation more accurately in slow motion.

it's funny because my impression is that with lower timescale you can get away with less substeps haha, which definitely doesn't seem to be the case in my situation. I will try your suggestions, thank you!
User Avatar
Member
4 posts
Joined: Nov. 2024
Offline
James, I'm not sure if you meant vellum substeps or DOP substeps, but I'm having luck with increasing the global DOP substeps by the same amount as the slow down, keeping the vellum solver substeps the same.
  • Quick Links