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Sequence FPS and Frame values revert when Physics Simulate is enabled and Auto Key is off

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
48/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Domain
design

Research direction

The report identifies sequence attachment properties, the Physics constraint’s Simulate control, and Auto Key in Spine 4.3.26, but names no source files or tests. Start by locating the code that handles sequence FPS and Frame edits and compare how edits are applied with Simulate on and Auto Key off. Done means FPS, Frame, and playback mode changes remain editable in that state.

Written by the indexing model from the issue text.

Description

bug

Description:
When a physics constraint's Simulate button is enabled and Auto Key is off, changing the FPS or Frame value of a sequence immediately causes the value to revert to its previous state.

The sequence's playback mode can be changed, but if the FPS is subsequently modified, the playback mode also reverts to its previous state.

This behavior may be related to #948, where active physics simulations caused unkeyed transform changes to revert.

Expected behavior:
Sequence properties should be editable regardless of whether physics simulation is enabled or Auto Key is on. When Auto Key is off, changes should remain until they are manually keyed or discarded.

Steps to reproduce:

  1. Download the attached .zip file: 1108-sequence-keying-issue.zip
  2. Open the Spine project file inside it using Spine 4.3.26.
  3. Switch to Animate mode.
  4. Make sure Auto Key is off and the physics constraint's Simulate button is enabled.
  5. Select the sequence attachment muzzle and try to change its FPS value from 12 to 24.
  6. You can see the FPS immediately reverts to 12.
Image

Simirally, if you try changing the sequence's Frame value, the Frame value also immediately reverts to its previous value.

Additional verification:
The following changes allow the sequence properties to be modified normally:

  • Disable Physics simulation: Turn off the Physics constraint's Simulate button while keeping Auto Key off. The FPS and Frame values can now be changed without reverting.
  • Enable Auto Key: Turn Simulate back on and enable Auto Key. The FPS and Frame values can also be changed normally.

Version where this issue was observed:
Spine 4.3.26

This issue was reported in the following forum thread:
https://esotericsoftware.com/forum/d/30726-43-sequence-cant-change-fps

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