FEM solver - Animated SBD Pin Constraint Problem

[LaszloFX]

Hello Everybody,

 

I'm working on a Cloth Simulation in which I'd like to have a set of points to be Pin Constrained.

But I'd like to change the Pinned point count over time, so it releases the constraints as the animation goes on.

 

In the documentation on constraints I've found this:

 

How to change the points that are constrained with the pin constraint during simulation

 

By default, the Constrained Points list does not expect the points to change. However, there is a way to work around this and have the list freshly evaluated by DOPs on every frame.

1. Right Click on the Pin Constraint node and select Allow Editing on Contents.

2. Dive into the Pin Constraint node and select anchorobjpointgrouppos1.

3. Change the Point Group parameter to Set Always.

   See the Anchor: Object Point Group Position help for more information on this node.

 

http://www.sidefx.com/docs/houdini15.0/dyno/constraints

 

So I've tried to do these steps but I couldn't get it to work for some reason. Maybe I'm missing something obvious.

I've uploaded a very simple scene file in which I've grouped a set of points and animated the grouping bounding box.

 

If it's no too much trouble would you guys mind taking a look at it and see if anyone can help me out with this issue?

 

Any help or advice is much appreciated.

 

 

Thanks for you time.

 

Cheers,

Laszlo

 

cloth_animated_pinConstraint_v001.hip

[Juraj]

Hi,

not sure if it is the cleanest way of doing it but it works.

 

Juraj

cloth_animated_pinConstraint_v002.hipnc

[Skybar]

Yes, the problem isn't what you think it is. As Juraj pointed out you need to update your group, since at the moment you are only bringing in the geometry at frame 1. Heres with a wrangle:

dv_cloth_animated_pinConstraint_v001.hip

[LaszloFX]

Thank you very much David and Juraj!

 

And yes it makes perfect sense to do it that way.

 

Thanks again for the help!

 

Laszlo