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Unity DOTS中创建一个AssetBundle并将其用作Entity

创建一个新的Unity项目，并确保已启用DOTS功能。
创建一个AssetBundle，可以通过在Project视图中右键单击文件夹并选择“Create > AssetBundle”来创建。
将您想要转换为Entity的资源（例如模型、纹理等）拖放到AssetBundle中。
创建一个新的C#脚本，用于加载AssetBundle并将其转换为Entity。以下是一个示例代码：

System间的数

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

public class AssetBundleToEntity : MonoBehaviour
{
public GameObject prefab;
public Material material;

void Start()
{
var entityManager = World.DefaultGameObjectInjectionWorld.EntityManager;

var entityPrefab = GameObjectConversionUtility.ConvertGameObjectHierarchy(prefab, World.Active);

Entity entity = entityManager.Instantiate(entityPrefab);

entityManager.AddComponentData(entity, new Translation { Value = new float3(0, 0, 0) });

entityManager.AddSharedComponentData(entity, new RenderMesh
{
material = material,
mesh = entityManager.GetSharedComponentData<RenderMesh>(entityPrefab).mesh
});
}
}

据传递

动态加载代码

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine;
using Unity.Entities;
using Unity.Transforms;
using Unity.Rendering;
using Unity.Mathematics;

public class DynamicAssetBundleLoading : MonoBehaviour
{
public string assetBundlePath;
public string assetName;
public Material material;

IEnumerator Start()
{
AssetBundleCreateRequest request = AssetBundle.LoadFromFileAsync(assetBundlePath);
yield return request;

AssetBundle assetBundle = request.assetBundle;

AssetBundleRequest assetRequest = assetBundle.LoadAssetAsync<GameObject>(assetName);
yield return assetRequest;

GameObject prefab = assetRequest.asset as GameObject;

var entityManager = World.DefaultGameObjectInjectionWorld.EntityManager;

var entityPrefab = GameObjectConversionUtility.ConvertGameObjectHierarchy(prefab, World.Active);

Entity entity = entityManager.Instantiate(entityPrefab);

entityManager.AddComponentData(entity, new Translation { Value = new float3(0, 0, 0) });

entityManager.AddSharedComponentData(entity, new RenderMesh
{
material = material,
mesh = entityManager.GetSharedComponentData<RenderMesh>(entityPrefab).mesh
});

assetBundle.Unload(false);
}
}

释放Entity

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

public class ReleaseEntity : MonoBehaviour
{
EntityManager entityManager;

void Start()
{
entityManager = World.DefaultGameObjectInjectionWorld.EntityManager;

// 创建Entity
Entity entity = entityManager.CreateEntity();

// 添加组件数据
entityManager.AddComponentData(entity, new Translation { Value = new float3(0, 0, 0) });

// 添加SharedComponent数据
entityManager.AddSharedComponentData(entity, new RenderMesh
{
material = GetComponent<Renderer>().material,
mesh = GetComponent<MeshFilter>().sharedMesh
});
}

void OnDestroy()
{
// 释放Entity
entityManager.DestroyEntity(entity);

// 释放相关的GameObject和AssetBundle引用
Destroy(gameObject);
Resources.UnloadUnusedAssets();
}
}

System以MonoBehaviour数据事件通知

在Unity的Data-Oriented Technology Stack (DOTS)中，如果您希望在ECS系统中的Job执行完毕后通知MonoBehaviour或外部代码，可以使用Unity的Events系统或自定义事件系统来实现通信。以下是一种常见的方法：

使用Unity的Events系统：
- 在MonoBehaviour中定义一个事件，当事件被触发时通知外部代码。
- 在ECS系统中，创建一个System，在System中检查Job是否执行完毕，并在适当的时机触发MonoBehaviour中定义的事件。
- using Unity.Entities;
  using UnityEngine;
  using UnityEngine.Events;
  
  public class JobCompletedEvent : MonoBehaviour
  {
  public UnityEvent onJobCompleted;
  
  public void TriggerJobCompletedEvent()
  {
  onJobCompleted.Invoke();
  }
  }
  
  public class JobCompletionSystem : ComponentSystem
  {
  protected override void OnUpdate()
  {
  // 检查Job是否执行完毕
  if (jobCompleted)
  {
  // 获取JobCompletedEvent组件
  JobCompletedEvent jobCompletedEvent = FindObjectOfType<JobCompletedEvent>();
  
  // 触发事件通知外部代码
  jobCompletedEvent?.TriggerJobCompletedEvent();
  }
  }
  }
- 自定义事件系统：
  - 创建一个自定义的事件系统，允许ECS系统和MonoBehaviour之间进行通信。
  - 在ECS系统中，触发自定义事件来通知MonoBehaviour或外部代码。
  - using Unity.Entities;
    using UnityEngine;
    
    public class CustomEventSystem : ComponentSystem
    {
    public delegate void JobCompletedEventHandler();
    public static event JobCompletedEventHandler OnJobCompleted;
    
    protected override void OnUpdate()
    {
    // 检查Job是否执行完毕
    if (jobCompleted)
    {
    // 触发自定义事件通知外部代码
    OnJobCompleted?.Invoke();
    }
    }
    }
IBufferElementData

要将DynamicBuffer与Entity关联，我们只需要定义需要的IBufferElementData，而不是DynamicBuffer本身，使用GenerateAuthoringComponent属性会自动帮我们生成DynamicBuffer并添加到Entity上，这里需要注意一下，下面定义一个简单的IBufferElementData看一下吧：

using Unity.Entities;

[GenerateAuthoringComponent]
public struct IntBufferElement : IBufferElementData
{
    public int Value;
}

添加与释放

EntityManager.AddComponent<IntBufferElement>(yourEntity);
EntityManager.RemoveComponent<IntBufferElement>(yourEntity);