I’m really loving the effect of a little soft translation on the spine for a squash/stretch type of motion, but everything drops/settles over the first 5-10 frames of the animation because of gravity, as gravity tends to do.
It’d be neat if there was a way to kind of set the starting pose as already affected by gravity so that when the sim starts it’s already ‘settled’, so you don’t see the pose drop.
I just saw a paper presented on this for hair sim. Annnnd I found it, here it is:
Or maybe, not entirely the same affect, a way to disable gravity for translation only? I don’t know. What do you guys think?
For completness and clarity, I think you are referring to this.
And what you’d like to avoid happening is the sag happening on the first few frames. Try applying an opposing force to your character with a Pin Constraint.
Finding the right value is going to be more art than science, as it depends on the anatomy and shape of your character, as well as how it is animated. But this should get you going.
But in those hair-examples above, the goal is having the hair end up in that position, after pre-roll. The challenge is finding how to counter-act gravity such that the hair does not fall any further. Modelers and art-directors typically want to approve a particular look, and having it then drop due to simulation is undesirable. So today, the solution would be to model it in a different pose, to manually counter-act what gravity will do once applied, and then try and approve that instead.
The same is true for ragdoll characters, for example someone sitting at a table, or simply just standing around. Sometimes you want the pose you start with to be your starting position (duh), but gravity has other plans.
There are ways to solve it - like in that paper - but that does not apply to rigid body dynamics. Good news is there are well-defined solutions for rigid body dynamics too and we’d like to incorporate one of them into Ragdoll at some point.
