Animating Voroni Fracture Points and Fixing the Resulting Geo

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Hello Everyone,

I'm relatively new to houdini so I apologize if this has been asked and answered somewhere else.

I’m looking to have voroni shapes move along the surface of an object by animating the fracture points. My issue begins when I use the divide sop to remove shared edges after the fracture. This allows me to use the resample and smooth sop to refine the shape. However if I extrude and bevel further down the line the primitives become bent and mangled due to the lack of subdivisions (especially when the original object is round). I’ve attempted to drop down a remesh sop to add subdivisions but they do not move with the animated mesh.

Attached is a project file. The look is very close to what I’d like to achieve just without, you know, those primitive errors. Also, if there is a better way to achieve this effect by starting over I’d love to know.

Thank you!
Edited by existenceproofllc - May 16, 2018 13:34:14

Attachments:
Rounded_Voroni_01.hiplc (233.1 KB)
Voroni_Screenshot_01.png (707.6 KB)
Voroni_Screenshot_02.png (1.1 MB)
Voroni_Screenshot_03.png (928.0 KB)

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Problem seems to be your triangulation can't handle deformation. Some things to test:

First of all, always try adding a “normal” node after these operations, might be that it's just a display issue.

Secondly. Transfer the normal from the mesh to the top points (using ray).

Third. After the extrude and bevel you know the desired height from the surface for the points, by using ray or wranglers you can mess around with the shape while guarantee the height stays the same. Like subdividing the top and raying against the source mesh to snap it to the correct height.

Could also be a good to test the divide>bricker function. (I'd probably try doing this after you've moved the primitive to a rest position to get a consistent topology between frames, this will take a bit of math though)
Edited by kahuna031 - May 17, 2018 14:48:48
B.Henriksson, DICE
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Fun exercise trying to build surfaces lazily with a one SOP solution.

Bjorn is correct in that you should be throwing a Ray SOP in there before you extrude.

Here is a few different tries of surfacing the curve faces with varying degrees of success. I thought the new PolyFill SOP with Quadrilateral Grid option would do it but I had to point jitter to try to fix some shapes and still. Meh…

In the end Remesh SOP with adaptivity enabled did a very nice artifact render free job.

Attachments:
rebuild_faces.jpg (227.0 KB)
Rounded_Voroni_01_jw.hipnc (814.8 KB)

There's at least one school like the old school!
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not sure why you need VDB ?

I've modded your file.

01) the EdgeGroup selection…shouldn't be that complicated…see my fix

02) add a normal…sweet as….damn fast too, don't see the need for VDBs

You can add a smooth if you want…

Attachments:
Rounded_Voroni_01_vu.hipnc (234.9 KB)

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Thank you for the responses!

Vu your fix works really well. I hadn't messed around with Normal modes and have taken some time to learn more about them. I was using the VDB to make the shape a bit more organic but the smooth sop you suggested works well too.
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