Unity Physicsの使用例

ItemGetSystem.cs

using Unity.Entities;
using Unity.Physics.Systems;

[UpdateAfter(typeof(StepPhysicsWorld))]
public class ItemGetSystem: ComponentSystem
{
    private BuildPhysicsWorld buildPhysicsWorldSystem;
    private StepPhysicsWorld stepPhysicsWorldSystem;

    protected override void OnCreate()
    {
        buildPhysicsWorldSystem = World.GetOrCreateSystem<BuildPhysicsWorld>();
        stepPhysicsWorldSystem = World.GetOrCreateSystem<StepPhysicsWorld>();
    }

    protected override void OnUpdate()
    {
        var physicsWorld = buildPhysicsWorldSystem.PhysicsWorld;
        var triggerEvents = stepPhysicsWorldSystem.Simulation.TriggerEvents;
        var items = GetComponentDataFromEntity<ItemTag>(true);

        foreach (var triggerEvent in triggerEvents)
        {
            // PhysicsWorldに全ての物理演算で動くEntityが含まれる。
            // triggerEventsには、Raises Collision Eventが有効なオブジェクトが接触イベントを格納する
            // TriggerEventの中身を洗えば、接触判定が取れる
            var bodyA = physicsWorld.Bodies[triggerEvent.BodyIndices.BodyAIndex];
            var bodyB = physicsWorld.Bodies[triggerEvent.BodyIndices.BodyBIndex];
            
            Process(bodyA.Entity, items);
            Process(bodyB.Entity, items);
        }
    }

    void Process(Entity entity, ComponentDataFromEntity<ItemTag> items)
    {
        if( items.Exists(entity))
        {
            PostUpdateCommands.DestroyEntity(entity);
            UnityEngine.Debug.Log("you get item!");
        }
    }
}