Choppy horizontal movement in avian2d platrofmer demo

[vladinator1000]

Heya, there seems to be a stutter when running the avian2d demo, I removed most of the level colliders to illustrate the issue:

2025-01-11.14-21-06.mp4

I'm on Windows 11, ran the demo with this command (set the wgpu backend env var to prevent log noise in the terminal):

$env:WGPU_BACKEND="dx12"; cargo run --bin platformer_2d --features avian2d

In the Avian docs, they have a PhysicsInterpolationPluigin so I thought that might help https://docs.rs/avian3d/latest/avian3d/interpolation/struct.PhysicsInterpolationPlugin.html

But it didn't, here are the things I've tried to debug using the above docs:

1. Adding a TransformExtrapolation and TransformInterpolation component to the setup_player function in for_2d_platformer.rs
2. Changing the physics plugin addition fn main in platformer_2d.rs to

               app.add_plugins(
                    PhysicsPlugins::new(FixedPostUpdate)
                        .set(avian2d::interpolation::PhysicsInterpolationPlugin::interpolate_all()),
                );

Possibly related links:

• Bevy time jitter issue Res<Time> is unreliable / jittery bevyengine/bevy#4669
• Avian jitter issue Jitter when making the camera follow a physics object Jondolf/avian#211
• Bevy discord help thread: https://discord.com/channels/691052431525675048/1327424197298753666/1327424197298753666

[idanarye]

I tried to run this locally while logging the X velocity, and it stayed the same during the run even though I've seen the stuttering. Since Tnua never mutates the transform, and the velocity remains constant - this is not Tnua's fault.

That being said - it does happen in both Avian2d and Rapier2d (though it's less noticeable in the latter). Maybe they do the same mistake?

[vladinator1000]

@idanarye that makes sense to me 🙌🏼 I opened an issue in Avian Jondolf/avian#625