# edge fracture

## Recommended Posts

Hi,

Do you guys know how to make this effect? I mean small pieces on the edges of fractured pieces. It is a part of keith kamholz's tutorial and i can't afford it because expensive for me.

Thanks.

##### Share on other sites

anyone can't show it with just simple box?

##### Share on other sites

this is my poor man's attempt...it's just a proof of concept, is all.

So you see I've defined the large chunks first, then break them up further to smaller pieces. In buffer_zone, you decide how far you want your 'rim' to be by transferring the outside border attribute of the large chunks to the smaller pieces inside. Then I simply show this with the color red.

Then you do something to the 'rim' area...like throw them up like confetti or something...as said, it's a poor man's attempt, just forcing myself to have a go that's all.

vu_frac_rim.hiplc

##### Share on other sites

like any good cook would say.................annnnnnnnnnnnnd here's one I prepared earlier......

(the effect itself is pretty amateurish...I just wanna see sumin' happenin' that's all)

Edited by Noobini

##### Share on other sites
On 2018-11-16 at 12:25 AM, Noobini said:

like any good cook would say.................annnnnnnnnnnnnd here's one I prepared earlier......

(the effect itself is pretty amateurish...I just wanna see sumin' happenin' that's all)

##### Share on other sites

Hi roberttt!

I did that specific fracture before the Houdini 16+ booleans were available, using a custom voronoi cutters technique.  Basically, I used boolean-style cutter geometry to guide a voronoi fracture.

1)  Scattered lots of points on the cutter geo, point-jitter them for width, and create cluster attributes on those points to create small clumps

2)  Create a band of voronoi points a bit further from the cutter geometry, to define the large chunks.  These points all get the same cluster value, and make sure that cluster value isn't used in the small-chunks clusters.

3)  Run the fracture with clustering.... although the new H17 voronoi fracture doesn't seem to have clustering built in.  So I believe you need to do the clustering post-fracture in H17, which unfortunately doesn't have an option to remove the unnecessary internal faces, so the geom can be a bit heavy with the new workflow.  (Unless I'm missing something obvious!)

I don't think I've used this voronoi fracture workflow at all since the H16+ booleans were released, and I've removed that technique from my CGMA destruction class.  Nowadays I would handle this in one of these ways:

- Running a primary boolean fracture to define the main chunks, and then running a secondary pass where I generate additional fragments on the edges of the main pieces.  There are various ways to generate those secondary boolean edge cuts, and it's always a bit experimental.

- Fracture everything at once into lots of small pieces, and use noise or geometry-grouping to define the larger shapes from the smaller fracture.  Then once those large chunks are defined, use constraints or the name attribute or double-packing to get them to behave as individual large pieces.

Hope this helps!    :-)

• 5

## Create an account

Register a new account