Boostrap.cs

using UnityEngine;
using Unity.Entities;
using Unity.Rendering;
using Unity.Transforms;

public class Boostrap : MonoBehaviour
{
    private World gameWorld, menuWorld;

    void Awake()
    {
        gameWorld = new World("Game World");
        menuWorld = new World("Menu World");

        gameWorld.CreateManager<MeshInstanceRendererSystem>();
        gameWorld.CreateManager<TransformSystem>();
        gameWorld.CreateManager<RenderingSystemBootstrap>();
        gameWorld.CreateManager<EndFrameTransformSystem>();
        // 中略
    }

    void OnDestroy()
    {
        gameWorld.Dispose();
        menuWorld.Dispose();
    }
}