Objective

Update Avian to Bevy 0.17!

Solution

• Migrate to Bevy 0.17.0-rc
• Rework collision events to work with the new event architecture
  • Combine CollisionStarted, CollisionEnded, OnCollisionStart, and OnCollisionEnd into CollisionStart and CollisionEnd events
  • All collision events are now both written as a Message and triggered as an Event
• Rename system sets from FooSet to the new FooSystems convention
• Remove manual type registrations
• Migrate to using Parry's new Bvh instead of the old Qbvh

Migration Guide

Collision Events

The CollisionStarted, CollisionEnded, OnCollisionStart, and OnCollisionEnd events have been replaced by the CollisionStart and CollisionEnd events. They are both written as a Message and triggered as an Event, and store the collider and body entity of both colliders involved in the event.

A collision event observer before:

fn on_player_stepped_on_plate(event: Trigger<OnCollisionStart>, player_query: Query<&Player>) {
    let pressure_plate = event.target();
    let other_entity = event.collider;

    if player_query.contains(other_entity) {
        println!("Player {other_entity} stepped on pressure plate {pressure_plate}");
    }
}

and after:

fn on_player_stepped_on_plate(event: On<CollisionStart>, player_query: Query<&Player>) {
    let pressure_plate = event.collider1;
    let other_entity = event.collider2;

    if player_query.contains(other_entity) {
        println!("Player {other_entity} stepped on pressure plate {pressure_plate}");
    }
}

A collision event reader system before:

fn print_started_collisions(mut collision_reader: EventReader<CollisionStarted>) {
    for CollisionStarted(collider1, collider2) in collision_reader.read() {
        println!("{collider1} and {collider2} started colliding");
    }
}

and after:

fn print_started_collisions(mut collision_reader: MessageReader<CollisionStart>) {
    // Note: The event now also stores `body1` and `body2`
    for event in collision_reader.read() {
        println!("{} and {} started colliding", event.collider1, event.collider2);
    }
}

System Sets

System sets have been renamed to follow the new FooSystems naming convention.

• PhysicsSet → PhysicsSystems
• PhysicsStepSet → PhysicsStepSystems
• SubstepSet → SubstepSystems
• SubstepSolverSet → SubstepSolverSystems
• SolverSet → SolverSystems
• IntegrationSet → IntegrationSystems
• BroadPhaseSet → BroadPhaseSystems
• NarrowPhaseSet → NarrowPhaseSystems
• SweptCcdSet → SweptCcdSystems
• PhysicsTransformSet → PhysicsTransformSystems

ColliderConstructorHierarchy

Bevy 0.17 changed the way Name works for glTF mesh primitives (migration guide). Instead of MeshName.PrimitiveIndex, it is now in the form of MeshName.MaterialName. This also means that APIs such as ColliderConstructorHierarchy::with_constructor_for_name now use this format.

ColliderConstructorHierarchy::new(ColliderConstructor::ConvexDecompositionFromMesh)
    .with_density_for_name("armL_mesh.ferris_material", 3.0)
    .with_density_for_name("armR_mesh.ferris_material", 3.0)