st-tech / st-tech/ppf-contact-solver

[Bug] Fast armature-driven collider introduces partial clipping with dynamic shells

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Dominant language
Python
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Description

Summary

When an armature-driven collider moves fast, dynamic shells in contact with it exhibit partial visible clipping (the shell appears to penetrate the collider surface in render rather than staying outside the contact offset).

Steps to Reproduce
  1. Animate a collider mesh via an armature with rapid motion.
  2. Place a dynamic shell in contact with the collider.
  3. Run the solver and inspect the contact region.
Expected Behavior

The shell should remain outside the contact offset of the collider at all times, with no visible interpenetration even under fast armature-driven motion.

Actual Behavior

Partial visible clipping appears at the contact region while the collider is moving fast; the shell intersects the collider surface in the rendered frames.

Image
Environment
  • OS: not OS-specific (reproducible on any supported platform)
  • GPU / driver:
  • Blender version:
  • Solver commit / version:- OS: not OS-specific (reproducible on any supported platform)
  • GPU / driver:
  • Blender version:
  • Solver commit / version:
Contribution Agreement
  • I confirm that any code, patches, scripts, attachments, or other copyrightable material I include in this issue may be used, reproduced, modified, and distributed by this project under the Apache License 2.0 or as otherwise described in CONTRIBUTING.md.
  • This is a bug report from the community (please provide a reference below).
Community Reference

https://x.com/szonszon/status/2059392382882214132?s=20

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the reported case: animate a collider mesh with an armature at high speed, place a dynamic shell against it, and run the solver while inspecting rendered contact frames. Trace the collider-motion and contact-offset handling involved in that reproduction; done means the shell remains outside the collider surface without visible clipping during fast motion.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
computer-graphics
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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