Hi, I'm new on Houdini and I'm from 3dsmax

I wanto to know how to reproduce the “volume select” modifier of 3dsmax, this modifier uses a volume (like box or cylinder) to select points or primitives on an object and has the option of soft selection for the result, it's very useful for proceduralism.

I did something like it using “group node” with bounding box optin but it has no sotf selection, if I use softxform I obtain what I want but only for position rotation scale operations, if I want to use a volume for select points in a soft way (like the softxform) and apply a deforming node (like twist) to the soft selection and later animate the “selector volume” to move the selection and the effect on the surface I don't find a way.

How can I do this on Houdini? I'm checking the help but I still dont find the solution, please help me…

thanks previously

Augusto

What you have to do is apply the deformation to the whole model and then use an attribute with a falloff in it to drive a blend (created in vops) to combine the original and the deformed model so as to get a soft transition between the two.
If I get time later I'll knock up an example…. unless someone else gets to it first…

Here's a hip file that covers a few methods. You can of course make the soft attribute in any way you like, even just manually paint it.

You can also wrap these networks up in an HDA so you don't have to keep rebuilding them all the time…

thank you simon, I'm going to study your solutions

In its simplest form would a metaball used as a magnet do what you want?

hi simon, this is what i did using your solution and is exactly what I was looking for, as you can see the solution is very slow, how can I speedup this system?

I also had to set the “number of threads” to no treading in the VOP SOP othervise I obtain a doubled selection, why this?

hi probbins, maybee I'm wrong, but what you say is similar to the softxform node?!?!?

There's a couple of things you can do…
What I've done here is modified the file in several ways.

1. I've switched the way the group is done so the attribute is created as 1 for where the effect happens, I originally had it the other way round, this might be slightly more efficient.
2. Because you are using a Vex sop to do the final deformation you can directly override the height parameter with an attribute (this only works for vex sops) so the blend sop isn't required.
3. Finally and most importantly I've replaced the attribute transfer method of blurring with the smooth sop method. The important thing here is to turn the cutoff frequency up to 3 or higher in order to get a large falloff.
4. I've also added a cache sop, although on my system this isn't required, it would help playback with even larger geometry.

If you only need a circular soft selection (or one that can be made from metaballs) you can use the magnet sop to generate the soft attribute and that would bypass the whole blurring and smoothing operation and be even quicker…

thank you simon! now all is good!
I was looking for a good softselection system both for sphere and custom geometries and that's it

in this occasion I also discovered the metaball node, it works good for a lot of things

Thanks also to probbins for the tip about the metaball, I was wrong about your affermation but I'm only a junior on Houdini, now I understand