Official New SubScene & ConvertToEntity workflows

@Opeth001

It would also seem that using both systems at the same time is very problematic. Since in your case both the proxy and conversion system seem to be trying to add the same component type to a single entity, which is not allowed and leading to that error.

 

Thanks, I've given this a try on a small test scene and it works. I'll have to try it on my bigger hierarchy in the near future.

In the meantime, what I ended up doing was just to have a hierarchy of normal GameObjects and another completely separate hierarchy of entities. Then I have a two component systems to keep them in sync: one that runs before any other system to copy data from the gameobject onto the entities, then a second that runs after the other component systems copy the entity data back onto the gameobjects. Its kind of a crap solution, but at least I don't have to rewrite a bunch of my monobehaviour scripts to make them work in ECS.

I still don't know why they don't let us use the 'Convert and Inject Game Object' on both parent and child objects in the same hierarchy. It feels like that would make things easier.

 

@addent Don't know if this is of any help on the matter but when creating a new "Authoring Component Type" script from the create menu it includes this note:

Not sure why this is recommended or if it applies to child object management though.

 

Checking out the Unity Physics package code, docs and samples is very helpful here since that system uses the conversion system extensively. By just looking through the Getting Started section of the manual I was able to learn that you could use the conversion utility class to convert the GameObject and children without even attaching a ConvertToEntity Script at all.

Code (CSharp):

1. using Unity.Entities;
2. using UnityEngine;
3.  
4. public class ConversionScript : MonoBehaviour
5. {
6.     void Start()
7.     {
8.         GameObjectConversionUtility.ConvertGameObjectHierarchy(gameObject, World.Active);
9.     }
10. }

Update: It seems the above code doesn't work for hybrid setups because it doesn't preserve and inject the original GameObject, and this is probably why it's giving me null reference exceptions whenever I try it.

Perhaps they could add a conversion mode flag or entirely new utility function so we can convert and inject the whole object through code. But for now it seems easiest to just keep using the old GameObjectEntity/Proxy for any children you'd like to convert and inject.

cc: @thelebaron

 

Thanks for the info. I have not touched the ECS physics example yet, but a cursory glance shows that I definitely need to dig through it to get a better understanding of this stuff.

 

It's referring to CreateAdditionalEntity method. You can use inside a GameObjectConversionSystem or IConvertGameObjectToEntity.Convert method:

Code (CSharp):

1. public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem) {
2.     var childEntity = conversionSystem.CreateAdditionalEntity(child);
3.  
4.     // ...
5. }

It's just the recommended way instead of calling dstManager.CreateEntity directly.

[]'s

 

What's the best way to get the entity associated with a converted GameObject? In the old system you could just do:

Code (CSharp):

1. gameObject.GetComponent<GameObjectEntity>().Entity

The ConvertToEntity class has no such reference to the entity, as far as I know.

 

You need to store yourself.

Code (CSharp):

1. public class EntityReference : MonoBehaviour, IConvertGameObjectToEntity {
2.     public Entity Entity { get; private set; }
3.     public World World { get; private set; }
4.  
5.     public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem) {
6.         Entity = entity;
7.         World = dstManager.World;
8.     }
9. }

* I'm on mobile so the code certainly has some typo.

[]'s

 

That's what I suspected. Thanks.

This method seems to be the key to converting select child objects to entities with the new conversion system. However, I still don't understand how to use it properly. If I call CreateAdditionalEntity in the parent script, passing it the child object, it gives me the error:

But I have no idea where or when I should be calling GetPrimaryEntity or what needs the reference. I tried calling it right before CreateAdditionalEntity, which gives me the error:

I can fix this error by implementing IDeclareReferencedPrefabs but than I just get the original error again.

 

I'm somewhat confused now.

When I try adding GameObjectEntity to a child object I get the warning message:

This strongly suggest that all children are supposed to be converted along with the parent. But this obviously isn't happening. Only the components attached to the parent/root GameObject are included in the conversion process (unless you use ConvertGameObjectHierarchy, which still doesn't work with injection). So I'm guessing this is now a bug.

 

When calling CreateAdditionalEntity you must pass a parameter that already has a "Primary Entity". In Inject Mode, only one entity will be created, the first one with ConvertToEntity in the hierarchy.
So you need create a additional entity based on this entity and add any other component manually, including parent/child relationship.
To make an entity to be a child of another, you need to add Parent and LocalToParent components.

EntityManager has a method called SetName that can help when you want to find a specific entity in Entity Debugger.

[]'s

 

@elcionap Thank you for all the info but I still don't really understand this system.

I actually just want to create an additional entity with the conversion system from a child object, just like the parent. I don't actually need or care about the entity parent/child relationship here. The issue is that placing a ConvertToEntity script on the child does nothing because the root ConvertToEntity script cancels it out. However, the warning messages seem to suggest that the system should at least convert all IConvertGameObjectToEntity scripts in the GameObject hierarchy to the primary entity but this isn't happening. And even using ConvertGameObjectHierarchy seems to only convert the transforms and none of the child IConvertGameObjectToEntity scripts.

The only solution I can think of right now is to separate the child into a prefab and instantiate it at run instead so the ConvertToEntity script attached to it actually runs, but this feels like a lot of work for such a simple objective and makes me want to go back to the old GameObjectEntity system.

 

@IsaiahKelly You only need the one ConvertToEntity script in your hierarchy, and you handle referenced GameObjects via whatever script implements IConvertGameObjectToEntity. I posted a snippet near the top of this page but to further elaborate:

Code (CSharp):

1. public class MyBehaviourAuthoring : MonoBehaviour, IConvertGameObjectToEntity
2. {
3.     public GameObject ChildWeapon; // A child in this gameObject's hierarchy
4.  
5.     public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem)
6.     {
7.         // - Add the immediate components the parent needs
8.         dstManager.AddComponentData(entity, new Health());
9.         dstManager.AddComponentData(entity, new CopyTransformFromGameObject()); // Or CopyTransformToGameObject - Only if you need to sync transforms
10.         // I believe that translation, localtoworld and rotation are automatically added to the root object that has the ConvertToEntity with Inject selected
11.      
12.         // - Create an entity for the PlayerWeapon gameObject and add components manually
13.         var weaponEntity = dstManager.CreateEntity();
14.         dstManager.AddComponentObject(weaponEntity, ChildWeapon.transform); // Add child transform manually
15.         dstManager.AddComponentData(weaponEntity, new Translation()); // Have to add all this stuff manually too
16.         dstManager.AddComponentData(weaponEntity, new Rotation());
17.         dstManager.AddComponentData(weaponEntity, new LocalToWorld());
18.         dstManager.AddComponentData(weaponEntity, new CopyTransformFromGameObject()); // Or CopyTransformToGameObject - Only if you need to sync transforms
19.      
20.         // - Only if you want the parent child relationship
21.         dstManager.AddComponentData(weaponEntity, new Parent{Value = entity});
22.         dstManager.AddComponentData(weaponEntity, new LocalToParent());
23.     }
24. }

I admit I don't remember if I tried what you posted above, as this has been working for me and in lieu of any official statement regarding the proper conversion of a hierarchy, I'll just be sticking with this for now.

 

@thelebaron I know you can do this all manually but that defeats the whole purpose of the conversion system. I also see you've been able to convert child objects before in a previous version. That and the warning messages I've received make be believe/hope this must be some kind of bug or oversight. Surely there must be a way to use IConvertGameObjectToEntity on child objects too. And if not there should be! Perhaps we just need some actual documentation on how to do this.

 

Oh my bad. Yeah an automated workflow would be nice. Also an automatic conversion of a hierarchy and child colliders without merging them into a mega collider would be really nice for animated characters, along with better joint authoring workflows.

 

Yeah, I believe this is the ultimate goal and Unity physics actually already automatically converts PhysX colliders for you with the conversion system. I also remember someone from Unity saying you should eventually be able to edit a bunch of transforms on a character in the editor and have them all converted at run-time for best performance, etc.

 

Did you tried ConvertToEntity.ConvertAndInjectOriginal static method? Unfortunately the method doesn't return the created entity but something like the EntityReference example above can be used for this.

I haven't tried the code but looking in the sources should work properly.

[]'s

 

@elcionap ConvertAndInjectOriginal is actually what is called when you set conversion mode to "Convert And Inject Game Object" so that doesn't change anything unfortunately:

Code (CSharp):

1.         void Awake()
2.         {
3.             if (World.Active != null)
4.             {
5.                 // Root ConvertToEntity is responsible for converting the whole hierarchy
6.                 if (transform.parent != null && transform.parent.GetComponentInParent<ConvertToEntity>() != null)
7.                     return;
8.              
9.                 if (ConversionMode == Mode.ConvertAndDestroy)
10.                     ConvertHierarchy(gameObject);
11.                 else
12.                     ConvertAndInjectOriginal(gameObject);
13.             }
14.             else
15.             {
16.                 UnityEngine.Debug.LogWarning("ConvertEntity failed because there was no Active World", this);
17.             }
18.         }

However, the comment here is helpful because it again says it should be converting the whole hierarchy, which it isn't.

 

I'd like to create a SubScene and transfer a procedural generated prefab into the SubScene by script.
This is possible by the content of

class SubSceneContextMenu

If a SubScene is created already I'd like to got the complete prefabs by transform and gameobjects.
But SubScene.GetComponentsInChilderen<transform> does not return the complete content.

A workaround would be to move the game objects out of the SubScene + rework, than rebuild the SubScene again. But nothing works in this case. Would love to have SubScene.GetContent(); or similar.

Does any one know how to read through the game objects in a SubScene and/or remove perhaps?

Thank you!

 

#### IsChildOf BUG ? #####

I'm using an editor window.
If the SubScene is open for edit then AnyGameObject.IsChildOf(SubScene.gameObject.transform) return always false for any game-object is inside the SubScene. Normally should be true.

Code (CSharp):

1. using Unity.Scenes;
2. public SubScene subScene;
3. public GameObject anyGO;
4. Debug.Log(anyGO.IsChildOf(subScene.transform));

 

Could be wrong on this one, but I suspect that isn't a bug. I don't think root objects in a scene have a parent - even if it's a subscene. However you could consider it unexpected behaviour.

 

Yes that true on a real scene and it has no transform in inspector. A SubScene has a transform component.
1) Now there is no way to determine what objects containing a SubScene I guess.

2) Another issue with the SceneManager. If a SubScene is closed, the SceneManager does not list the SubScene. At runtime it's not possible to find and load a SubScene.

And there are other issues with SubScene, when editing prefabs in Hlod.cs, duplicating and insert SubScenes. It really requires a hands on.

Code (CSharp):

1.           using UnityEngine.SceneManagement;
2.             Scene[] Scenes = new Scene[SceneManager.sceneCount];
3.             for (int i = 0; i < SceneManager.sceneCount; i++) {
4.                 Scenes[i] = SceneManager.GetSceneAt(i);
5.                 Debug.Log(Scenes[i].name);
6.             }
7.  

 

1. Except it doesn't really. If you make changes to the SubScene transform it does not affect the scene transforms (and even warns this.)



I always imaged subscenes were designed to really just be 1 scene that you've broken into parts. It should work exactly the same if all the subscenes were just a single scen and entities shouldn't really care if they are part of a subscene or not.

If you want them at runtime separate, you can just load a scene of entities classically with
SceneManager.LoadSceneAsync, You don't have to use a subscene.

Anyway really just my interpretation. I suspect they'll be fleshed out a lot more in the future making them more versatile.

 

A warning is not an argument to block a required feature. Isachild of should definetely return true on the subscene has a transform attached. This is a required technical solution.for a minimum workflow. Or, did you have a solution to list the gameobjects of a SubScene?

The scenemanager doesnt know about a closed subscene.

 

Does the Conversion of a hierarchy happen in a reliable order?

For example, are parent GameObjects always converted before their children?

 

I didn't see any responses to this question. I'm running into what sounds to be the same kind of hybrid situation, but now I'm wanting to create a custom world and I'm not finding any way to achieve that. It would be very easy for me to get a reference to world in question into an IConvertGameObjectToEntity MonoBehaviour, but I'm not sure what I would even do with it from there to "move" the entity over to that world.

UPDATE: fwiw I tried setting World.Active to my custom world, but I can't seem to make that happen before the conversion happens, so I see the IConvertGameObjectToEntity method called on my hybrid objects before my MonoBehaviour (which I have set to extremely high negative priority) gets a chance to create the custom world.

 

is there plans to add Baked shadows and lights to Subscenes soon ?

 

@Joachim_Ante , sorry if I am asking a question you already answered, I can't seem to find the answer anywhere, but: what are the plans for baking support? We're working on a project that uses the "New SubScene & ConvertToEntity workflows" and it requires us baking lights. I am not too sure what the alternatives could be in the meantime.
Thanks!

 

All of the link in github is broken. Should changed URL from

../Samples/..

to

../ECSSamples/..

 

What is the best way to create an entity from a gameobject while being able to reference components like rigidbody from the editor? I got it to work by placing a converttoentity component where I chose inject game object. But then I seem to have the original object lying around in the scene (which makes sense because it was in the scene to begin with). Should I create a prefab and load that, or can you make an entity from a gameobject in the scene, without duplicating it AND have the entity retain the rigidbody component?

 

@scotthNM @Opeth001 @ben_unity9

 

I don't think you understand how the conversion system works. Classic GameObject components can not be directly added to an entity, they can only linked to the entity from a GameObject. So the original GameObject must still exist if you want to have any classic components associated with the entity. The "inject GameObject" conversion option does exactly this by not destroying the GameObject after conversion, so you can still access it's components.

This also means you need to keep related values in sync between the entity and GameObject. So for something that affects translation like a rigidbody, you need to keep the GameObject and associated entity translation in sync using something like the CopyTransformFromGameObject component or your own custom sync system.

 

Is there a best practice for instantiating hybrid prefabs at runtime after the initial scene load? It takes a very long time (in excess of 17ms) to instantiate GameObjects that have a Convert-and-inject conversion component attached to them. Most of that time is spent in GameObjectConversionUtility.CreateConversionWorld(), with a decent amount of time also spent in GameObjectConversionUtility.Convert(). Is there any way to hold onto a conversion world for reuse since I know I'll occasionally be needing it to instantiate hybrid prefabs?

 

RectTransform conversion is finally fixed. I started rewriting my UI system to ConvertToEntity workflow but quickly encountered another problem. Editor (2019.3.0a11) crashes even with very simple RectTransform hierarchies. I already reported the issue (1175841) with simple reproduction project. I hope you can fix it in a reasonable time because it's blocking my UI development.

 

Yes. I tested it on 2019.1.14f1 and it crashed too. Unfortunately, no crash report or stack trace. Editor log stops here:

 

Hello!

Is there a way for a conversion system to "hide" components from other conversion systems?

I'm mapping out camera boundaries in ProBuilder, but I don't want the meshes converted, or even the transform really.

My CameraBoundaryConverter will look for game objects with the CameraBoundary component and create a correctly filtered physics collider. I would like that same system to also prevent other conversion systems from running on that object - either all of them, or I specify components to "hide" from other converters (like transform and mesh filter).

Thanks~

 

I'm also curious if I'm doing something wrong here. Is this expected and it's a known shortcoming of the game object conversion system that will eventually get dealt with, or am I coming at this from the completely wrong angle wrt instantiating hybrid objects not at the time of scene load?

 

If I have SubScenes open in edit mode it doesn't seem to run any entity conversion at all, but I have some GameObjects that only work as entities and do nothing as Monobehaviors. Is there a way to force these to run through entity conversion when entering play mode even when the SubScene is open for edit?

 

What does your conversion system script look like

 

Somehow bug disappeared after a few changes in my systems. It looks like ConvertToEntity triggered a hidden bug in my UI implementation. The good news is that it wasn't a bug in ConvertToEntity workflow. The bad news is I couldn't trace it because there were no stack trace or crash dump. Anyway, the case is reported. We should get nice message where we made a mistake and why the engine crashed.

 

Straight forward Convert method, just calls AddComponentData, which lets it get picked up by some systems that do the work.

 

@Joachim_Ante

In subScene.cs EntityManager should be public.

Code (CSharp):

1. // ... SubScene.cs Class
2. [NonSerialized] EntityManager _SceneEntityManager;

Access to the SubScene EntityManager is extremely useful.
EditorRenderData.PickableObject contains the managed gameobject and all properties.

SubScene also should contain some delegates to prevent pooling. Open/Close/etc..

Code (CSharp):

1. using Unity.Entities;
2. using Unity.Scenes;
3. using Unity.Transforms;
4. using UnityEngine;
5.  
6. [ExecuteAlways]
7. public class SubSceneExplorer : MonoBehaviour {
8.     public EntityManager subSceneEntityManager;
9.     public SubScene subScene;
10.  
11.     // .. Simple Test    
12.     private void Update() {
13.         if (subScene == null) subScene = GetComponent<SubScene>();
14.  
15.         // subScene.IsLoaded = true  // Scene is "Open for Edit"
16.         // subScene.IsLoaded = false // Scene is     "Closed"
17.         if (subScene.IsLoaded)  Debug.Log("SubScene " + this.name + "Open for Edit");
18.         if (!subScene.IsLoaded) Debug.Log("SubScene " + this.name + "Closed");
19.  
20.         Debug.Log("subScene._SceneEntityManager " + (subScene._SceneEntityManager != null));
21.         Debug.Log("subScene._SceneEntityManager.IsCreated " + (subScene._SceneEntityManager.IsCreated));
22.  
23.         // ... Check for Entities are created on Close SubScene
24.         if (subScene._SceneEntityManager != null && subScene._SceneEntityManager.IsCreated) {
25.  
26.             subSceneEntityManager = subScene._SceneEntityManager;  // ... Get the EntityManager
27.             var Entities = subSceneEntityManager.GetAllEntities(); // ... Get the Entities itself
28.  
29.             foreach (var entity in Entities) {
30.                 var components = subSceneEntityManager.GetComponentTypes(entity);
31.  
32.                 // Each entity contains several components in a SubScene EntityManager
33.                 // Some can be access via GetSharedComponentData() some by GetComponentData()
34.  
35.                 // <EditorRenderData>        GetSharedComponentData
36.                 // <SceneTag>                    GetSharedComponentData
37.                 // <Child>                        Not Accessable
38.                 // <SceneSection>               GetSharedComponentData
39.                 // <Translation>                GetComponentData                      
40.                 // <Rotation>                    GetComponentData                      
41.                 // <LocalToWorld>             GetComponentData                      
42.  
43.                 // ... Run each component on an entity
44.                 foreach (var comp in components) {
45.  
46.                     // ... Get the corresponding GameObject from <EditorRenderData>PickableObject
47.                     if (comp.GetManagedType() == typeof(EditorRenderData)) {
48.                         var erd = subSceneEntityManager.GetSharedComponentData<EditorRenderData>(entity);
49.                         var go = erd.PickableObject;
50.                         // Do anything with
51.                     }
52.  
53.                     // Debug.Log(comp.GetManagedType().Name);
54.                     // var ch = subSceneEntityManager.GetComponentData<SceneTag>(e);
55.  
56.                     if (comp.GetManagedType() == typeof(Translation)) {
57.                         var pos = subSceneEntityManager.GetComponentData<Translation>(entity);
58.                         // Disable/Move Objects on collision.
59.                         subSceneEntityManager.SetComponentData(entity, new Translation { Value = pos.Value });
60.                     }
61.                 }
62.             }
63.         }
64.     }
65. }
66.  

 

@Joachim_Ante
Also fwiw, I'm realizing this isn't only a problem after scene load. I'm trying to load scenes asynchronously now and getting very large waits (can get over 100ms for even a single convert-to-entity GameObject) as soon as I activate the scene. Should I be avoiding the conversion system and come up with something simpler and faster if I essentially just need access to transform/sprite/animator?

 

What is the difference between subscene and prefab? Is one recommended over another? They both seem to address identical use cases to me.

 

A prefab is game object structure based on referenced game objects. These references structures are placed in a scene called a prefab.

A subscene contains a prefabs structure and/or unique objects are converted to a linear memorylayout to render faster.

Does it exolain a bit what you ask for?

 

The problem is, where is the line that separate between it?

Why shouldn't prefab be used in place of subscene while prefab can contain another prefab?
Why shouldn't subscene be used in place of prefab while subscene can contain raw gameobject?

 

Why does a ProBuilder mesh work fine with ConvertToEntity but not work at all when placed in a SubScene?

 

Why not compile all static objects of a hierarchy into a SubStaticScene at start and render by dots? All is possible, for sure. At least this is a human factor require to separating things proximately without loosing overview and running into unmanageable dependencies. This is a wise decision of experience separating the man from the boys.