[SOLVED]Crumple Piece Of Paper?

[Atom]

HI All,

 

I am trying to take a flat sheet of paper and crumple it up. I have not really used the cloth section of Houdini but I thought I would give it a try. The concept behind the scene is that I have a large sphere around the paper with a mountain SOP and the normals are inverted so they point inward. The sphere is a Static Dynamic Object that I am animating smaller so that when it interacts with the flat cloth the cloth will have no other place to go except inward on itself into a pseudo spherical shape (i.e. a crumpled wad of paper).

 

However, as the simulation cooks the paper flys out of the collider almost immediately. I do have gravity turned off in the sim.

 

How do I tame the cloth simulator?

Is there a better way to construct this effect other than cloth?

 

Thanks

ap_paper_crumple_1a.hipnc

Edited September 21, 2015 by Atom

[Skybar]

As usual with problems involving collisions, take a look at how your collision geo actually looks like in dops. Judging by your picture there, it looks singlesided and will probably behave like a solid rock. Naturally anything inside will shoot out because it cannot be inside.

[NSugleris]

I'd inverse the shape and extrude out so its just huge solid with a small cave inside.   Could try that to see if it helps.

[pezetko]

In your case turn on "Invert Sign" checkbox on your RBD Object, and you will need to turn on Use Deforming Geometry as well probably.

[Atom]

I have 'hollowed' out the sphere by merging to spheres with different radi. Is this good enough for the cloth sim to detect?

I am still getting no action out of the simulation. I am wondering what I did wrong?

ap_paper_crumple_1b.hipnc

[loopyllama]

You're using the Bullet solver which likes convex collision shapes. The RBD solver will let you have the collision geometry you seek.

 

Change to the RBD solver instead of the Bullet Solver in rigidbodysolver1. In your sphere_cloth_collider_crumpler checkmark the Invert Sign and use Laser Scan with a division of 40. Set your stiffness low on your cloth object. Maybe 10. Lastly move your gravity to be directly after your cloth solver so it won't affect the collider. Turn on your collision guide on your crumpled sphere to see what the solver is going to get in the way of collisions. Also, you don't need two spheres so just disable that sphere_inner node.

[Atom]

Thanks for the suggestions loopyllama.

 

I applied the settings to the last posted scene and I still can not get any action out of the cloth paper. As you can see in the image, the crumpled sphere does collapse but it never seems to affect the paper?

ap_paper_crumple_1c.hipnc

Edited September 19, 2015 by Atom

[mestela]

Had a quick go, found I could only get reliable collisions by using a volume collider. 

 

(click to play)

 

paper_crumple_v01.hipnc

[Atom]

Thanks Matt, your setup is very close what I was going for. I've been playing around with the scene all morning.

 

One thing I notice is that if I apply a UV Unwap and a UV Quickshade to the cloth as the simulation progresses, the UVs dance around.

 

Is there any way to lock the UV coordinates in a cloth sim?

.

.

.

Ah, it was the UV Unwrap, if I use a UV Texture instead, the coordinates lock down.

Edited September 19, 2015 by Atom

[stickman]

Sorry for being such a noob... I've been checking the scene out (so cool!).
I try and fail at introducing a modeling iteration. I'd like to introduce a deformation / morph / model process to first create a broader folding form (app frames 5-20) before the more uniform crumple deformation happens. Here a ripple.
It seems to have no affect. It's before the DOPimport node in the cloth item, so I thought it would influence what the DOPNetwork has to work with. A ripple option in the DOP network itself only creates a new mesh. How / where do you introduce a modeling iteration? Is it because I have keys on the effect? I find no option to have the DOP respect animation or such.
 

paper_crumple_v02dm.hipnc

Edited January 15, 2017 by stickman