[Sidefx-houdini-list] image based fracturing

Ken Ouellette ken.ouellette at gmail.com
Thu Apr 29 12:36:21 EDT 2010


I guess it depends on your texture you are using for your crack.

I usually would pre-build images for the TraceSOP so it it was a white
(crack) on a black background with a 1 or 2 pixel border in white.
Since the white thin pixel border is the first primitive the SOP makes you
can always delete it with a blast for prim 0.

Again depending on what your image is you are using to generate the crack...
the remove border option on the traceSOP can be handy. If your image is
complex and it starts creating unique shapes (convex and concave) you will
have some difficulty isolating, but it is really dependent on your image.

hope that helps.
-k

2010/4/29 François Duchesneau <sidefx at trinix.ca>

> You're right Andrew. Look out at this example file. It does just that.
>
> http://www.trinix.ca/mhug/?page_id=12
>
> If my memory is right, the trick I've found to make it work is to use
> the Trace Sop followed by a snap in the Fuse Sop but not too strong.
> Don't try to make it work completely there. Let it have many small
> spaces between the junctions of surrounding pieces. With a Group Sop
> create a group for "Boundary Edge" and then fuse those points only.
>
> However you still need a texture with uniform line width so you'll have
> to trace over a cheap crack texture found on the web maybe. Play with
> the threshold on the Fuse Sop but you will also need to fix the texture
> in some spots too.
>
> That's my poor implementation of Blast Code but if anyone has a better
> algorithm that allows a poor quality texture like Blast Code can handle,
> I'd like to know.
>
> François
>
> Andrew D Lyons wrote:
> > You're right - my "off the top of my head" has issues.
> >
> > The fuse SOP snap functionality helps with that a little - but there's
> > still cleanup to do after that even. Anyone else got ideas?
> >
> > Cheers
> >
> > On 28 April 2010 22:00, Shaun Galinak <shaun at neonshaun.com> wrote:
> >
> >> With a trace sop, won't you always get those bordered edges?
> >> Is there any way to get rid of those, so you have clean
> piece-against-piece
> >> geometry?
> >> I thought hole faces would take care of it, but it doesn't seem to
> help...
> >>
> >> -Shaun
> >>
> >> --------------------------------------------------
> >> From: "Andrew D Lyons" <tstexture at gmail.com>
> >> Sent: Wednesday, April 28, 2010 8:25 PM
> >> To: <sidefx-houdini-list at sidefx.com>
> >> Subject: Re: [Sidefx-houdini-list] image based fracturing
> >>
> >>
> >>> Well that's kinda what I'd call 2d - but nevermind. The trace SOP
> >>> followed by an extrude, some point position noise and then a facet
> >>> (unique points) could be your ticket....
> >>>
> >>> On 28 April 2010 16:25, Jim VanAllen <jimvanallen at gmail.com> wrote:
> >>>
> >>>> ideally 3-d, something extruded with a bit of noise to create
> interesting
> >>>> edges.
> >>>>
> >>>> On Wed, Apr 28, 2010 at 4:22 PM, Andrew D Lyons <tstexture at gmail.com>
> >>>> wrote:
> >>>>
> >>>>> Is it a planar breakup or 3D?
> >>>>>
> >>>>> If it's planar (like broken glass) you might be able to use a Trace
> SOP?
> >>>>>
> >>>>> Cheers
> >>>>>
> >>>>>
> >>>>> On 28 April 2010 16:19, Jim VanAllen <jimvanallen at gmail.com> wrote:
> >>>>>
> >>>>>> Hi,
> >>>>>>
> >>>>>> I'm trying to figure out the best way to take an image of some
> cracks
> >>>>>> (like broken glass), and use it to break up a mesh in Houdini. I've
> >>>>>> used some of the other techniques for fracturing a mesh, but we're
> >>>>>> trying to figure out this specific problem, and my Houdini memory is
> >>>>>> failing me at the moment.
> >>>>>>
> >>>>>> Any ideas?
> >>>>>>
> >>>>>> - jim
> >>>>>> _______________________________________________
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> >>>>>>
> >>>>>>
> >>>>>
> >>>>> --
> >>>>> =======================================
> >>>>> Andrew D Lyons | Digital Artist | http://www.tstex.com
> >>>>> =======================================
> >>>>> _______________________________________________
> >>>>> Sidefx-houdini-list mailing list
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> >>>
> >>> --
> >>> =======================================
> >>> Andrew D Lyons | Digital Artist | http://www.tstex.com
> >>> =======================================
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