UnityECS学习08-GameObjectSync

GameObjectSync

首先在主场景中添加 Toggle 和一个空物体 Directory。将后者挂上脚本：

// Directory.cs
namespace HelloCube.GameObjectSync
{
    public class Directory : MonoBehaviour
    {
        public GameObject RotatorPrefab;
        public Toggle RotationToggle;
    }
}

挂载后将我们的预制体和 Toggle 都拖入。

接下来创建 DirectoryInitSystem.cs：

namespace HelloCube.GameObjectSync
{
    public partial struct DirectoryInitSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<Execute.GameObjectSync>();
        }
        
        public void OnUpdate(ref SystemState state)
        {
            state.Enabled = false;

            var go = GameObject.Find("Directory");
            if (go == null)
            {
                throw new Exception("GameObject 'Directory' not found");
            }

            var directory = go.GetComponent<Directory>();

            var directoryManaged = new DirectoryManaged
            {
                RotatorPrefab = directory.RotatorPrefab,
                RotationToggle = directory.RotationToggle
            };

            var entity = state.EntityManager.CreateEntity();
            state.EntityManager.AddComponentData(entity, directoryManaged);
        }
    }

    public class DirectoryManaged : IComponentData
    {
        public GameObject RotatorPrefab;
        public Toggle RotationToggle;

        public DirectoryManaged()
        {
            
        }
    }
}

• 首先将 state.Enable 设置为 false ，调用一次之后就关闭，防止多次创建 cube。
• 接着就是获取到场景中的 Directory 物体，从其身上的脚本拿到我们的预制体和 Toggle。注意此处的 DirectoryManaged 是 class 的，因为我们使用的是托管的数据。

接着又创建一个 RotatorInitSystem.cs：

namespace HelloCube.GameObjectSync
{
    public partial struct RotatorInitSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<Execute.GameObjectSync>();
            state.RequireForUpdate<DirectoryManaged>();
        }

        public void OnUpdate(ref SystemState state)
        {
            var directory = SystemAPI.ManagedAPI.GetSingleton<DirectoryManaged>();
            var ecb = new EntityCommandBuffer(Allocator.Temp);

            foreach (var (rotationSpeed, entity) in SystemAPI.Query<RotationSpeed>().WithNone<RotatorGO>()
                         .WithEntityAccess())
            {
                var go = GameObject.Instantiate(directory.RotatorPrefab);
                ecb.AddComponent(entity, new RotatorGO(go));
            }
            
            ecb.Playback(state.EntityManager);
        }
    }

    public class RotatorGO : IComponentData
    {
        public GameObject Value;

        public RotatorGO(GameObject value)
        {
            Value = value;
        }

        public RotatorGO()
        {
            
        }
    }
}

• 查询 subscene 中存在 RotationSpeed 并且没有 RotatorGO 也就是无 prefab 实体的 entity，Query 只能得到 Component 加上 WithEntityAccess() 可以访问对应的 entity。

接着在 RotationSystem.cs 中做类似于第一次的查询，只需在 OnUpdate 中修改了旋转如何赋值回给 RotatorGO 中的 GameObject 即可

namespace HelloCube.GameObjectSync
{
    public partial struct RotationSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<Execute.GameObjectSync>();
            state.RequireForUpdate<DirectoryManaged>();
        }

        public void OnUpdate(ref SystemState state)
        {
            var directory = SystemAPI.ManagedAPI.GetSingleton<DirectoryManaged>();
            if (!directory.RotationToggle.isOn)
            {
                return;
            }

            float deltaTime = SystemAPI.Time.DeltaTime;

            foreach (var (transform, speed, go) in SystemAPI
                         .Query<RefRW<LocalTransform>, RefRO<RotationSpeed>, RotatorGO>())
            {
                transform.ValueRW = transform.ValueRO.RotateY(speed.ValueRO.RadiansPerSecond * deltaTime);
                go.Value.transform.rotation = transform.ValueRO.Rotation;
            }
        }
    }
}