[Sidefx-houdini-list] Recursive cookie in many axis

Ben Schrijvers ben.schrijvers at guerrilla-games.com
Tue Aug 28 04:39:16 EDT 2007


I've done some breakup tools before using cookie but it was just too 
unstable.
As I'm now creating geometry for games the cookie has another bad side 
effect in that it creates unwanted/unnessecary polygons because of the 
nessecary pre-triangulation.

At the moment I'm testing H9 and the new volume primitive type is saving 
the day.
That combined with voxel noise shaders and I'm getting full 3D voronoi 
breakup.

cheers,
benS


Andrew D Lyons wrote:
> The Volume idea sounds nice. It would be of immense value to have some
> kind of a 3D voronoi break up routine in Houdini that worked like
> this.
>
> http://www.cs.cornell.edu/Info/People/chew/Delaunay.html
>
> I made a Houdini procedural break up tool that kind of what you wanted
> at a previous place of employ. It used the "Foreach" Sop system that
> was on odforce, but you could now use the For SOP in Houdini 9. It
> used the cookie sop, and procedurally generated cylindrical cutters.
> There was a bit of checking for bad topology and other undesirable
> outcomes which would occasionally occur in the process of 100
> iterations with a cookie sop and a random cutter. From memory, the
> basic algorithm was:
>
> 1./ Use input bounds to build cutter to suitable scale.
> 2./ Add random orientation, position and point displacement to cutter points.
> 3./ Make cut.
> 4./ Check connectivity for only 2 objects.
> 5./ Measure surface area of two objects
> 6./ Feed all objects back into 1 and cut the biggest object in the next pass.
>
> It worked OK with some hand holding, but it wasn't really that elegant
> a solution in comparison to the voronoi type solutions that could be
> done.
>
> http://compgeom.cs.uiuc.edu/~jeffe/compgeom/demos.html
>
> I'd definitely like to add weight to the various RFEs that are open
> for a break-up tool of this sort. It would be sooo handy with DOPs...
>
> Cheers
>
>
> On 26/08/07, sidefx at trinix.ca <sidefx at trinix.ca> wrote:
>   
>> I'm hesitating about using a recursive mechanism to break objects apart
>> for a volume object that has to be cut in many axis, not only in the same
>> plane like a window. I tried it but the result wasn't an artistically
>> viable solution.
>>
>> My conclusion is, if it's for background chunk objects then it can be
>> usefull. If it's for "hero chunks" or even for mid distance chunks then
>> you need to decide where the cutters are.
>>
>> I wonder what you think about it and does anyone have an idea how we could
>> cut  procedurally an object such as a sphere to make it look as if made of
>> stone with nice turbulence deformation. It would be even better if we
>> could provide the chunk's density by setting an attribute on a point cloud
>> or volume primitive in world space inside the object but it's probably an
>> utopian idea.
>>
>> Thanks for feedbacks
>>
>> François
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>>     
>
>
>   




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