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shawn_kearney

Is Voronoi pre-fracture obsolete?

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I'm sorry if my newb is showing, but I am curious about people's thoughts on this. Now that I have VDB Fracture working, I cannot really see myself using Voronoi fracture in SOP (ETA - What I mean here is as opposed to RBD Fracture). Am I just missing out on something important, or is VDB just the way to go? When would Voronoi be the better choice?

Edited by shawn_kearney

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Well first of all: VDB's are SOPS.

And of course isnt the Voronoi SOP obsolete. I guess its one of the most important SOP in Houdini. Do it first with the shelf tools and afterward from scratch.

So create a i.e. Polygonsphere. Shelf / moddelling / shatter and BOOM. Thats the most essential way in prefragmenting an object with the voronoi sop. Its a wide field. Just take a search here and use the help from houdini. Take a survey with with a search for "Houdini voronoi fracture tutorial" on vimeo / youtube..... tons of stuff...

Good Luck

Edited by Follyx

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What is VDB fracture?

Are you just converting pieces after the fact?

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12 hours ago, Follyx said:

Well first of all: VDB's are SOPS.

And of course isnt the Voronoi SOP obsolete. I guess its one of the most important SOP in Houdini. Do it first with the shelf tools and afterward from scratch.

So create a i.e. Polygonsphere. Shelf / moddelling / shatter and BOOM. Thats the most essential way in prefragmenting an object with the voronoi sop. Its a wide field. Just take a search here and use the help from houdini. Take a survey with with a search for "Houdini voronoi fracture tutorial" on vimeo / youtube..... tons of stuff...

Good Luck

First of all, I'm not doubting you at all. As popular as Voronoi is and as new as I am to Houdini I feel like I must be overlooking things. Even asking this makes me feel foolish. But one reason I'm wondering is because in Jeff Wolverton's Image-based Destruction tutorial he mentioned off-hand that there are better ways to do fracture, but did not discuss what those were (FEM seems like it'd be overkill). Perhaps it was some other approach to Voronoi (i.e. RBD Fracture), but it seemed like he didn't care for Voronoi in general. 

But I have used Voronoi some, and by comparison VDB Fracture SOP is generally faster both in set up and performance for complex interior noise, and much easier to control (though large numbers of small, detailed pieces are still problematic, though so is true of voronoi).

Add a platonic, subdivide, copy onto point and displace points with mountain sop. I can control the exact shape, placement, size and interior noise of pieces with a high degree of visual feedback before cutting up fractures.

Yes, from my limited experience I can get the same results when doing a basic fracture as explained above. Buteven for a basic random fracture VDB fracture just seems more responsive and direct. Like I said, probably I'm missing something. I'm just not sure what it would be.

 

3 hours ago, Atom said:

What is VDB fracture?

Are you just converting pieces after the fact?

VDB fracture is a SOP that cuts SDFs into multiple primitives based on mesh input. You then use Convert VDB sop to import into DOP normally. It's not immediately obvious how it all works and there aren't many tutorials out there.

Edited by shawn_kearney

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Most destruction artists worth their salt will talk in negative terms about 'out of the box' Voronoi fracturing because the patterns are instantly recognisable. But thats not to say that Voronoi is good for nothing. Going beyond default Voronoi is all about the manner in which you cluster those Voronoi fragments, the constraint networks and types of constraint you use (some swear by a mix of glue and cone twist), the deformations you use on edges and interior faces, and the manner in which you art direct your destruction sims via metaballs and the SOP Solver.

I love the VDB toolset in Houdini but I'm not totally sold on VDB fracturing as it can be difficult to get glitch free texturing when upresing from the low poly sim.

Another thing that separates the good from the average is the quality of the source model and the range of materials simulated (wood, plasterboard, concrete and brick etc, stc etc).

Voronoi fracturing isn't the enemy of destruction sims but a lazy reliance on the Voronoi shelf tool is.

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11 hours ago, shawn_kearney said:

Awesome reply, @jonmoore

There are some great threads here on od|force that go into detail regarding those techniques (and many with example files too). You're unlikely to use all those techniques in a single sim but the approaches should be part of your thought process when planning your effect.

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I've known about clustering, but it makes sense now how clustering can help here. I've always thought of clusters more thinking in terms of the dynamics and how the fracture plays out, I wasn't really thinking of it in terms of the overall shape of the pieces. You've given me a lot to think about.

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On 25.1.2017 at 0:09 AM, shawn_kearney said:

I'm sorry if my newb is showing, but I am curious about people's thoughts on this. Now that I have VDB Fracture working, I cannot really see myself using Voronoi fracture in SOP (ETA - What I mean here is as opposed to RBD Fracture). Am I just missing out on something important, or is VDB just the way to go? When would Voronoi be the better choice?

 

On 29.1.2017 at 5:04 PM, shawn_kearney said:

First of all, I'm not doubting you at all. As popular as Voronoi is and as new as I am to Houdini I feel like I must be overlooking things. Even asking this makes me feel foolish. But one reason I'm wondering is because in Jeff Wolverton's Image-based Destruction tutorial he mentioned off-hand that there are better ways to do fracture, but did not discuss what those were (FEM seems like it'd be overkill). Perhaps it was some other approach to Voronoi (i.e. RBD Fracture), but it seemed like he didn't care for Voronoi in general. 

But I have used Voronoi some, and by comparison VDB Fracture SOP is generally faster both in set up and performance for complex interior noise, and much easier to control (though large numbers of small, detailed pieces are still problematic, though so is true of voronoi).

Add a platonic, subdivide, copy onto point and displace points with mountain sop. I can control the exact shape, placement, size and interior noise of pieces with a high degree of visual feedback before cutting up fractures.

Yes, from my limited experience I can get the same results when doing a basic fracture as explained above. Buteven for a basic random fracture VDB fracture just seems more responsive and direct. Like I said, probably I'm missing something. I'm just not sure what it would be.

 

VDB fracture is a SOP that cuts SDFs into multiple primitives based on mesh input. You then use Convert VDB sop to import into DOP normally. It's not immediately obvious how it all works and there aren't many tutorials out there.

So let us know what your are want to develop? What kind of destruction, in wich cases you want to use it etc. Or just post a hip....

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