How can I do this procedurally (select and shrink loop)

   3101   24   3
User Avatar
Member
31 posts
Joined: March 2025
Offline
How can I do this procedurally

Create a square polygon, develop it 10 by 10 squares. That is a total of 100 squares - sub-polygons

Then go to edge mode select a peripheral loop and make shrink that the selected loop would be close to the center.
User Avatar
Member
19 posts
Joined: Jan. 2019
Online
this is a simple VEX-free solution

User Avatar
Member
379 posts
Joined: Aug. 2018
Offline
Here's another way:

Group1:
Group type primitives
Base group > switch off
Include by Edges > Unshared edges

Group Invert:
Group1

Group Promote:
Group 1
Auto to Edges
Include Only Elements on the Boundary
Edited by Mike_A - May 19, 2025 11:19:55
User Avatar
Member
31 posts
Joined: March 2025
Offline
atitimar
this is a simple VEX-free solution


Very cool but partly difficult. Thanks. Why can't this forum give an award to someone who offers solutions?
Edited by Artadecram - May 19, 2025 15:01:40
User Avatar
Member
31 posts
Joined: March 2025
Offline
Mike_A
Here's another way:



Yes, thanks!

But the resulting edge loop is not a peripheral loop

I need to get peripheral loo. then shrink it almost to center point and grow it back and so infinitely

strangly that so powerful software has no thrink and grow nodes
Edited by Artadecram - May 19, 2025 15:17:18
User Avatar
Member
379 posts
Joined: Aug. 2018
Offline
If I understand what you want, you can just add an 'Group expand' SOP after 'Group invert' and animate the step parameter.

** EDIT **
Example file attached. Play the animation. Is this the effect you want?
Image Not Found
Edited by Mike_A - May 19, 2025 17:56:07

Attachments:
shrink expand selection.hiplc (97.2 KB)

User Avatar
Member
31 posts
Joined: March 2025
Offline
Mike_A
I understand wh
Example file attached. Play the animation. Is this the effect you want?
Image Not Found
User Avatar
Member
31 posts
Joined: March 2025
Offline
Mike_A
If I understand what you w


Thanks for keep helping



Thats what i need!

Naturally, the selection of loops should be procedural - not manual like in my example
Edited by Artadecram - May 20, 2025 11:58:11
User Avatar
Member
379 posts
Joined: Aug. 2018
Offline
Did you download the file attached to my post above?
User Avatar
Member
31 posts
Joined: March 2025
Offline
Mike_A
id you download the file attached to my post a



Yes, and thanks again
In you video it's very easy to be discouraged because you keep showing an example through the demonstration of selected polygons, and I just want edges - that there would be no polygons at all.

Okay - I'll study your video again
User Avatar
Member
31 posts
Joined: March 2025
Offline
Mike_A
Did you download the file attached to my

Finally-- I figured it out.

Removed the last two pitches that were confusing me.

Put the polygons in the edges and yes - by moving the slider I got what I wanted.

I'm considering this as a solution!!! - Thanks
User Avatar
Member
21 posts
Joined: May 2024
Offline
Mike_A
id you download the file attach


Hi

I have partly the same task - how to procedurally select this outer edge?


Your text to link here... [limewire.com]
User Avatar
Member
5043 posts
Joined: Feb. 2012
Offline
Fordencore1966
Mike_A
id you download the file attach


Hi

I have partly the same task - how to procedurally select this outer edge?


Your text to link here... [limewire.com]

You can do it using the Group Create SOP:

Attachments:
gc.png (1.5 MB)

Senior FX TD @ Industrial Light & Magic
Get to the NEXT level in Houdini & VEX with Pragmatic VEX! [www.pragmatic-vfx.com] https://lnk.bio/animatrix [lnk.bio]
User Avatar
Member
21 posts
Joined: May 2024
Offline
animatrix_
You can do it using the Group Create SOP:

Mike_A
Did you download the file atta



Thanks!!

Yoy can seу that all selected edge are allocated in the same plane but in my cse i need slect only "upper cut"


Firstly i need to select the original edge - any original edge and then begin to grow it endge in sucha a way



How do you catch the original - initial edge?
How to select all upper cuts without potholes cyclically or in one go?
Edited by Fordencore1966 - May 27, 2025 10:29:25
User Avatar
Member
31 posts
Joined: March 2025
Offline
Fordencore1966
How do you catch the original - initial edge?
How to select all upper cuts without potholes cyclically or in one go?


Yeah, that's really interesting.
User Avatar
Member
2 posts
Joined: May 2025
Offline
Fordencore1966
Yoy can seу that a

The cut may not lie on the same plane - this is a child's version - the cut may "wiggle" or have errors in relation to the cut off section, that is, it is necessary to write a node program so that it would highlight not only ideal "upper cut" but also errors. But the errors should not exceed the "potholes".

It is necessary to understand which edge belongs to the original slice, but at the same time not to have a selection to the left and right of itself that would set 3 edges that are correct for further expansion.... - I remember solving this problem in a different editor before - I didn't solve it.
Edited by Arttemplar1942 - May 27, 2025 10:43:30
User Avatar
Member
9280 posts
Joined: July 2007
Offline
Fordencore1966
How do you catch the original - initial edge?
group it while it is an original edge higher in the stream
Houdini doesn't always preserve edge groups through SOP operations but it may work in your case
however it's difficult to say what operations you did and what your "original edge" looked like before whatever operations followed next

for example:
- Sphere SOP
- Clip SOP: Clipped Edges On (this will output "original" clipped edges in a group)
- Blast SOP: delete a few polygons on borders to create those cavities
the "clippededges" group will contain just the original clipped edges
Tomas Slancik
CG Supervisor
Framestore, NY
User Avatar
Member
21 posts
Joined: May 2024
Offline
tamte
group it while it is an original edge higher in the stream

Thanks for help-reaction

The point is that the sphere can be cut at any angle and then several polygons are made on this cut.
That is, there is no initial original edge - after each new slice of the sphere this same slice will be different

It is necessary to select those edges which by their appearance belong to one object (multyedge) and this multyedge should be between two potholes. So it is necessary to select all such multyedges. And group them.
User Avatar
Member
31 posts
Joined: March 2025
Offline
Fordencore1966
The point is that the sphere

Maybe first select all the open edges and then subtract the potholes from them
But first we need to let houdini understand what belongs to a slice.

Basically we need to understand which combinations of edges have the same pattern and then we have the solution.

Because as it was said above, the curvature error of the multyedge is much smaller than the potholes.
User Avatar
Member
9280 posts
Joined: July 2007
Offline
Fordencore1966
tamte
group it while it is an original edge higher in the stream

Thanks for help-reaction

The point is that the sphere can be cut at any angle and then several polygons are made on this cut.
That is, there is no initial original edge - after each new slice of the sphere this same slice will be different

It is necessary to select those edges which by their appearance belong to one object (multyedge) and this multyedge should be between two potholes. So it is necessary to select all such multyedges. And group them.
Did you try what I suggested? The Clip SOP will generate the group for you with the slice edges, so doesnt matter that each cut is different as the edges created by the slice will be in that group regardless of whether the holes existed before or were created by deleting some polys after the clip
Edited by tamte - May 27, 2025 19:59:35
Tomas Slancik
CG Supervisor
Framestore, NY
  • Quick Links