tyPush "Push Splines" does not respect Spline Influence soft-selection

[YOHEI MIYAHARA]

Hi,
I’m testing tyPush (Push Splines) together with Spline Influence in 3ds Max, but I’m running into unexpected behavior.
What I’m trying to achieve
I want to:

Use Spline Influence to create a soft selection on a spline,
then use tyPush to push only that influenced area.

Basically: sphere affects part of the spline → only that area should deform.
Modifier stack

Code:

Editable Spline 
→ Normalize Spline 
→ Spline Influence 
→ tyPush (Push Splines / Simple or Clip)

What actually happens

• The soft selection from Spline Influence is correctly passed up the stack
  (verified using an XForm modifier, it reads the selection properly).
  
• However, tyPush seems to completely ignore the influenced selection and instead:
  • Pushes the entire spline.
    
  • Endpoints move abnormally far (sometimes exploding or folding).
    
  • Some knots don’t move at all, regardless of the influence.
    
  • Sometimes the whole spline shifts upward globally.
    

Additional notes

• The spline is an open spline (not closed) – more like a cable/rope/tentacle.
  
• Tested both Simple and Clip modes in Push Splines.
  
• Knot types were tested with Bezier and Corner.
  
• Selection clearly works for XForm, but tyPush doesn’t seem to respect it.
  
• It feels like tyPush’s spline mode is optimized for closed shapes rather than open splines.
  

Question
Is this:

1. A limitation of tyPush’s spline implementation?
   
2. A known bug with soft selections on shapes?
   
3. Or am I missing a required setup step?
   

If possible, is there a recommended way to use tyPush together with Spline Influence for deformations on open splines?
Thanks!

[tyFlow]

It would be best if you could post a scene file where you're experiencing the issues.

tyPush - Spline/simple mode doesn't currently take selections into consideration - that's correct. If you post a scene with your setup and desired result, I can take the issues you're seeing into consideration when updating the modifier.

[YOHEI MIYAHARA]

It would be best if you could post a scene file where you're experiencing the issues.

tyPush - Spline/simple mode doesn't currently take selections into consideration - that's correct. If you post a scene with your setup and desired result, I can take the issues you're seeing into consideration when updating the modifier.

Hi Tyson,
Thanks again for your reply earlier.
As requested, I prepared a small scene file demonstrating the issue I'm experiencing when using tyPush → Push Splines together with Spline Influence on an open spline.
Environment:

• tyFlow 1.131
  
• 3ds Max 2024
  

---

Current understanding of the implementation
After reviewing the documentation, my understanding is:

• Use vertex selection applies only to Push vertices
  
• Currently, Push Splines (Simple / Clip) does not take knot selections, soft selections, or Spline Influence weights into account
  

So the behavior I’m seeing appears consistent with the current specification.
I just want to confirm whether Push Splines is intended only for full-spline offsets, without partial deformation support.

---

What the scene demonstrates
Right side – Expected behavior (with XForm)

• Spline Influence generates a correct soft selection on the open spline
  
• XForm applies deformation only to the influenced knots
  
• Moving the Influence Helper shifts the deformed region smoothly
  

Left side – Actual behavior with tyPush

• Simple mode: pushes the entire spline, ignoring the influence
  
• Clip mode: spline collapses or breaks unpredictably
  
• End knots move excessively or invert
  → This confirms that tyPush currently does not evaluate spline knot selection or weights.
  

---

Feature request / question
For workflows involving ropes, cables, tentacles, and other deformable open splines,
being able to push only the influenced section of a spline (e.g., based on Spline Influence weights) would be extremely useful.
Is partial spline deformation something that might be supported in a future update,
or is Push Splines intended to remain a full-spline offsetting tool?

---

Scene contents

• Open spline
  
• Normalize Spline
  
• Spline Influence (Sphere)
  
• XForm (shows expected result)
  
• tyPush (Simple / Clip)
  
• Influence Helper for visualizing the difference
  

If you'd like, I can prepare additional examples (closed splines, multi-segment splines, etc.).
Thanks again for your time and consideration!

[tyFlow]

Thanks for the file - selection-based spline tyPush will be available in the next build.