Solve wires that appear and disappear over time

   3424   2   2
User Avatar
Member
3 posts
Joined: 3月 2012
Offline
Hi,

I'm trying to make a wire simulation with a changing count of wires over time, but the solver gives an error saying the topology doesn't match.
Is there a way of adding new wires (that are not yet created in the initial frame) to the simulation while they appear?

I would appreciate if someone could help me with this, I've attached a sample scene. Thanks in advance!

Attachments:
dynWireConn.hipnc (134.9 KB)

User Avatar
Member
3 posts
Joined: 3月 2012
Offline
Maybe I should reformulate the question, cause I tried some things to make this work and had no success.

What would be the best way to create a wire object for each curve dynamically?

In the sample scene a sphere goes through a sphere cloud, and curves are created between this sphere and near spheres by its distance, so curves are being created and destroyed over time. I would like that this curves start to move like wires with gravity until they are destroyed, with the curve tips constrained to the spheres (I made a group called “constraints” for this). Is this possible in Houdini?
User Avatar
スタッフ
2540 posts
Joined: 7月 2005
Offline
At this point in time you can't change the topology for Wire Objects.

You can try to use the Cloth Solver on the wires. I usually sweep them in to a narrow ribbon and sim the thin strips of cloth.

Just so you know, you are resampling the curves in such a way that you are changing the number of points all the time. The idea is to assign the “pointoanimation” float attribute set to 1 for the first and last vertex of each curve but if you are constantly shuffling those points about, you are really asking a lot of any sim engine.
Change the resampling to a fixed number of points.

See the attached wip for using the Cloth Solver to do this. If you ignore the first few frames where the forces are huge and causes cloth to freak, it settles in to a pretty nice and controllable sim.

I added the time honoured BlendShapes SOP technique to blend the original with the dynamic sim for user control over the total amount of deformation.

If you could start out with the topology nicely formed before you start the sim, it would help the starting energies and reduce the first few frames geo freak-out.
The cloth tries to solve all the ribbons as a single sim object piece of cloth and as you remove and add new strands, it tries to map over the previous point energies to the new ones. A better solution would be to sim each ribbon as a net new cloth object with the start frame being the frame the cloth ribbon was added. Not supported by the default settings but could be possible to rig up as a DOP object is a DOP object as far as a cloth sim engine is concerned and will solve whatever is fed in to it at the current time step.

Attachments:
dynwireconn_164_sim_as_cloth.hipnc (276.4 KB)

There's at least one school like the old school!
  • Quick Links