NewComponentDataArraySampleSystem.cs

using Unity.Entities;
using Unity.Transforms;
using Unity.Collections;
using Unity.Mathematics;

public class NewComponentDataArraySampleSystem : ComponentSystem
{
    ComponentGroup playerGroup, enemyGroup;

    protected override void OnCreateManager()
    {
        // コンポーネントの準備
        playerGroup = GetComponentGroup(
            ComponentType.ReadOnly<Position>(),
            ComponentType.ReadOnly<Player>(),
            ComponentType.Create<HitPoint>());
        enemyGroup = GetComponentGroup(
            ComponentType.ReadOnly<Position>(),
            ComponentType.ReadOnly<Enemy>());

        RequireForUpdate(playerGroup);
        RequireForUpdate(enemyGroup);
    }

    protected override void OnUpdate()
    {
        // チャンクからNativeArrayを取得
        var playerPositions = playerGroup.ToComponentDataArray<Position>(Allocator.Persistent);
        var playerHitpoint = playerGroup.ToComponentDataArray<HitPoint>(Allocator.TempJob);
        var enemyPositions = enemyGroup.ToComponentDataArray<Position>(Allocator.TempJob);

        // 一定距離になったらPlayerにダメージ的な例
        for (int enemyIndex = 0; enemyIndex < enemyPositions.Length; enemyIndex++)
        {
            for (int playerIndex = 0; playerIndex < playerPositions.Length; playerIndex++)
            {
                if( math.distance( enemyPositions[enemyIndex].Value, playerPositions[playerIndex].Value) < 1)
                {
                    var hitpoint = playerHitpoint[playerIndex];
                    hitpoint.Value -= 1;
                    playerHitpoint[playerIndex] = hitpoint;
                }
            }
        }

        // ダメージを反映
        playerGroup.CopyFromComponentDataArray(playerHitpoint);

        // お片付け
        playerPositions.Dispose();
        playerHitpoint.Dispose();
        enemyPositions.Dispose();
    }
}