Page MenuHome

Simulations do update animations on frame rate change
Open, Needs Triage by DeveloperPublic

Description

System Information
Operating system: Linux-5.0.0-23-generic-x86_64-with-Ubuntu-19.04-disco 64 Bits
Graphics card: Mesa DRI Intel(R) UHD Graphics 620 (Kabylake GT2) Intel Open Source Technology Center 4.5 (Core Profile) Mesa 19.0.2

Blender Version
Broken: version: 2.81 (sub 1), branch: master, commit date: 2019-08-12 18:44, hash: rB3c014fe3fb7c
Worked: (optional)

Short description of error
Note I currently have only tested rigid body physics, this might affect other physics types as well.
The issue is that changing the frame rate after physics have been assigned to an object will change the speed of the animation.

Exact steps for others to reproduce the error

  1. Add rigid body physics to default cube
  2. Play animation. the cube should fall about 5 meters (4.905 to be exact) after the default 24 frames (1 sec)
  3. Change frame rate to 60
  4. Play animation. the cube should fall about 5 meters (4.905 to be exact) after 60 frames (1 sec)
  5. Animation is the same even after clearing and rebaking the cache. The only solution I found is to add and remove the rigid body physics.

Details

Type
Bug

Event Timeline

In my tests here I just cleaned the cache and the new frame rate works as it should. What happens is if you cache rigidbody at 24fps and then change the frame rate to another value like 60fps the playback will use that cached frames at 24fps and playback that cache with the new 60fps, resulting in a faster playback only on that cached(at 24fps) section of the timeline. that's why you should clean your cache (just changing some physics values) when you change the frame rate of your project.
What could help here is if you change the fps value it could clean the cache for you... but I'm not sure if it "should" clean the cache...