Hi,

i'd like to know would you do to create a vellum on an animated source :



Here is my base animated mesh.

It's a blend using a “f@blend” attribute. The blend goes from 0 to 1 : 1 means that the grid is unfolded.

What I want to do with vellum is :
use the f@blend attribute to drive constraints. It starts with a “pin to target” (soft type) with high stiffness value, that decrease based on the f@blend (f@stiffness *= (1 - f@blend) ).
When the (1 - f@blend) reaches 0, the grid use a standard “cloth” constraints.

But the problem I have is how to animate all these constraints.
First, the cloth constraint is calculated on first frame, so the constraints are all collapsed.
Then, even with a geometry wrangle in the vellum solver, I can't get the animated “f@blend” to calculate the stiffness…

So i'm stuck. I've also tried to do it inside a DOP Network and SOP Solvers, but no success.

All of this could be great for example on growing plants or other scaling stuffs

Thx !

Attachments:
vellum_anim.gif (1004.9 KB)
vellum_scaling_objects_001.hip (562.0 KB)

Well, i've found some tricks to do what I want…

First, i've created my base constraints : one cloth constraints with export ‘basestretch’ and ‘basebend’ groups, second with “pin to target” in soft type and respective “pinstretch” et “pinbend” groups.




Then I used a SOP Solver (I didn't know that it would work) inside the vellum solver, to update the constraints from a external node (/CONST1/ in my case).



This will update all the constraints from the base animation to the vellum solver so that you'll have correct restlength.

And finally, I used a vellum constraint property with a VEXpression to get my f@blend attribute from a custom node.



It's working ! I didn't check other cases. I don't know if it's a “clean” way to do it, but it's still a solution .

If someone know another method, share with us

Attachments:
vellum_base_constraints_01.jpg (29.4 KB)
vellum_base_constraints_02.jpg (57.0 KB)
vellum_solver_01.jpg (27.7 KB)
vellum_solver_constraint_properties_01.jpg (47.7 KB)
vellum_solver_SOPSolver_01.jpg (31.5 KB)
vellum_scaling_objects_002.hip (622.3 KB)