[Sidefx-houdini-list] fracturing a grid with polygonal curves?

sidefx at trinix.ca sidefx at trinix.ca
Fri Aug 24 20:42:21 EDT 2007

I don't know if I'm missing something but I can seperate every chunk of
geometry without the need of any closed polygon.

1-Extrude each curve with a depth scale of 1 and set the depth offset to
-0.5. (don't plug them in a merge)
2-Plug the grid in the A input of the Cookie
3-Plug on of the curve in input B of the Cookie
4-Set "Operation" on the cookie to "User Defined" and keep inside A and
outside A only
5-Plug this output of this into an other cookie and plug the other curve
in B and so on. Don't care about the group in the Cookie Sop for now.
6-Put a connectivitiy node at the end of it followed by a Partition Sop
and you get all your groups created.

Note that you can have more than one geometry at each cookie in input A as
long as you have only one curve in input B as long those geometry in A are
not intersecting within each other.

Of course to make it more flexible by allowing an arbitrary number of
section curve you would have to use the new ForEach Sop.

Now I let you find a way to find which of those chunk touches the point
because now I got to go doing my laundry ;) Please tell me if it works for


Darran Edmundson wrote:
> Thanks Mario and Andrew for the advice.  Prior to posting I had tried
the Cookie approach by closing each curve (ensuring to keep clear of the
grid's bounding box), extruding a volume and then doing the boolean.
Couldn't quite get it to work.  Mario, for implementing your algorithm,
will a pure vex solution outperform doing it via SOPs and expressions?
Or do I need to go the HDK to see an appreciable speedup?
> Cheers,
> Darran.

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