Torn Paper - Edge Detail

[ParticleSkull]

Hey guys,

I'm trying to add detail to some ripped paper mesh. This is the kind of detail i'm trying to achieve:

I almost achieved it using this workflow:

EDIT: THIS WORKFLOW DOESN'T WORK AT ALL (it sucks btw  )

1 - Give the paper (grid) a little thickness using a PolyExtrude

2 - Get the PolyExtrude's Side Group and apply a new PolyExtrude on it

3 - Get the new PolyExtrude's Front Group and add displacement on it (usign attribute vop)

This would totally work if the paper kept it's thickness.

Here's what I need:

http://imgur.com/kbonbMT

and here's what happens:
http://imgur.com/grzS4FT

I'd really apreciate if you guys have a better idea on how to proceed, even with a totally different workflow  

File is attached in case someone would like to have a look

Thank you,
Alvaro

paper boards v1a.rar

Edited January 26, 2017 by ParticleSkull
old idea doesn't work at all. Don't want to confuse people who read the 1st post.

[davpe]

hi, you just have to limit your displacement to X and Z axis (make 3d noise > convert vector to float > convert float to vector > leave Y component disconnected > add the result to P) and you're done.

Edited January 26, 2017 by davpe

[Atom]

Here is my attempt at implementing David's suggestions.

ap_paper boards v1a.hipnc

[ParticleSkull]

Thank's guys, unfortunatelly I've just realised this workflow doesn't work on my real scene. Check it out:

This hole is generated on a simulation. I have another idea on how to extrude the borders (it's on the file) but have no idea on how to add a noise displacement to it.. I'm totally running out of ideas now  
 

Rip Paper FEM 1bb.rar

Edited January 26, 2017 by ParticleSkull

[davpe]

well I think this shouldn't be much more complicated. instead of filtering by world axis you have to filter by primitive normals and multiply Y by zero. (at least I think it should work this way

btw. if you do this before extrusion you'll make your life easier

Edited January 26, 2017 by davpe

[ParticleSkull]

Thx again @davpe, but how can I filter by primitive normal? 

[davpe]

I'll try to make an example when I have some time later. I'm not able to be more specific without actually trying it bcs it always turns out that in reality things are never that easy

but basically what I would try to do is to take a local @N of primitives and then limit the displacement to the directions that are not @N (with use of a Dot product).

[ParticleSkull]

Thank you very much David, I really apreciate your help. I understand what you said but my lack of knowledge sucks, I'm still trying it though

[davpe]

hi, I made the example. the file is attached. It does the job but the math is a bit quirky (frankly, I'm quite surprised it actually works  ). I'd love to see a cleaner solution if anybody happen to come up with one.

cheers, D.

torn_edges_example.hipnc

Edited January 29, 2017 by davpe

[ParticleSkull]

YEAH

That's awesome, thank's David. I'll dissect it now

[davpe]

hey, I played with this little bit more today. It's actually quite useful  This is cleaner solution and gives nicer result. Still I believe it could be implemented much better though  file attached.

torn_edges_better.hiplc

Edited January 30, 2017 by davpe