Panic with SpringJoint

[brookman]

Hi. I'm new to rapier and tried to start with a simple example where I add a single SpringJoint between two bodies. However the application immediately panics.

How I set up the bodies:

    commands
            .spawn(SpriteBundle {
                sprite: Sprite {
                    color: Color::rgb(0.5, 0.5, 1.0),
                    custom_size: Some(Vec2::new(10.0, 10.0)),
                    ..default()
                },
                transform: Transform::from_xyz(
                    rand::random::<f32>() * 100.0,
                    rand::random::<f32>() * 100.0,
                    0.0,
                ),
                ..default()
            })
            .insert(RigidBody::Dynamic)
            .insert(Collider::ball(5.0));

How I tried to add the joint:

let joint = SpringJointBuilder::new(1.0, 1.0, 1.0)
    .build();
 commands
    .entity(entity_a)
   .insert(ImpulseJoint::new(entity_b, joint));

The panic

thread 'Compute Task Pool (0)' panicked at /home/user/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rapier2d-0.18.0/src/dynamics/solver/joint_constraint/joint_velocity_constraint.rs:335:31:
index out of bounds: the len is 4 but the index is 18446744073709551615
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Encountered a panic in system `bevy_rapier2d::plugin::systems::step_simulation<()>`!
Encountered a panic in system `bevy_app::main_schedule::Main::run_main`!

Am I doing something wrong?

[sebcrozet]

Hi! This will be fixed by dimforge/rapier#603 (merged but not released yet).

[brookman]

Thank you for the quick reply. 👍

In case anyone else runs into the same issue before the fix is released: I could get it working by overriding the transitive dependency in my Cargo.toml like this:

[dependencies]
bevy = "0.13.2"
bevy_rapier2d = "0.25.0"
rand = "0.8.5"

[patch.crates-io]
rapier2d = { git = 'https://github.com/dimforge/rapier', rev = "81f05f26b056247e21c6cd0b8cb187a64f181131"}

I had to use the specific commit ID because there are other, incompatible changes on the main branch.