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How to create voronoi curved surface (no inside group)

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Hi,

I have a simple question but after hours researching i couldn't find an answer yet..... i'm trying to create a voronoi curved surface but after trying this approach: voronoi fracture/blast-inside group/divide-remove shared edges i get the voronoi cells on the curved surface but each cell is disconnected. I also tried tweaking the "fuse" setting in the voronoi sop to connect all the cells and add a fuse sop in the end but for some reason the cells vertex never get fused.

Does someone knows how to create a voronoi curved surface without those straight edges from the original geo?

I'm attaching some images as references to i i'm looking for as the end result. Any help is appreciated.

Cheers

bd75bd8f4eebe4cc2c3c2153e1733ffa.jpg

6a40af584fe4398093b1539f6da1f4c2.jpg

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I think a displacement shader is the way to go! So you could use the voronoi pattern directly on your shader to use the center of each voronoi cell and the distance, then use that gradient as your displacement factor to give a concave or convex shape to your main object.

In sops you could do the same, but you need a lot of subdivision to accomplish the same as in shading stage.

Cheers,

Alejandro

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Hi Alejandro,

Thanks for your input. For this project, i have to create a geometry instead of renders only. I'm trying to extract the voronoi cells from the original mesh edges, as they are mixed in the result and then fuse the vertices of the isolated voronoise cells. I haven't reached that result yet. When i turn on the vertex display, i can see that the voronoi fracture sop creates vertices along the cells edges and i suspect that those are the reason why i cannot fuse them. Ant steps towards the goal....

Thanks!

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just checking...how do you know the fuse didn't work ? to me, Fuse does work...

If you are checking by using Explode...then Explode separates the prims by name..it doesn't mean the geo is physically separated. So in my test, if you disable delete_name....the Explode works, if you clear out name, Explode does not work.

Next test, if you disable fuse...and the Explode is using Auto Detect...then even if name was deleted....it will as the last option (per helpcard) use connectivity to separate the pieces....hence showing Fuse does work.

vu_egg_voronoi.hipnc

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Hey Noobini,

Thanks for your reply.

So, the intention for the project is not creating any rigid body simulation or anything exploding... i only need to create a surface with the voronoi cells that are clean and connected so i can later manipulate the cells adding poly extrude, for loop etc.... Checking your file, i see that you fused all the cells as i already tried but there are still vertices along the cells edges making them not usable for later manipulation. I haven't tried using the exploded view sop because i want the inverse of exploding the cells which is connected cells, no need for it...

I wonder why the voronoi fracture sop automatically disconnects the cells, maybe because the sidefx folks thought about it only for sims? Keeping the original edges from the previous geometry state is great for sims but would be interesting having some options within the sop to remove original edges and connect the cells. I'm sure that there are ways to implement this through VEX but i'm not fully versed in VEX yet. I hope that in the future versions of Houdini, SideFX can take a look at the voronoi fracture sop and add some more options to it.

Cheers

Egg_Voronoi.JPG

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Posted (edited)

have a look here: about mid way down

where i did straight voronoi...no points in between...

just on the voronoi, you can untick the connect inside and then disable the delete_inside node...

Edited by Noobini

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Thanks for pointing it out. I saw some stuff that Junichiro has posted, he's offering great tutorials for the community. On his voronoi tutorial, he points exactly how to use code to clean the edge points and create new polys, exactly what i was curious about.

My approach to this problem was creating a new poly from scratch with no divisions, scatter points to it, connect to the voronoi fracture, use fuse sop with increased distance and then connect to ray sop. It works but there is definitely some extra work to do with complex shapes. Junichiro's approach is much more bullet prooff

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well did you check my straight_voronoi file that i uploaded ?

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Yea, that is a solid solution! Thanks man.

One question, how come the inset in the poly extrude sop doesn't work?

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not sure which file you're referring to...try unticking Use Common Limit

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