Remove converted entitites that I don't need

I have noticed that I have some prefabs that I need to feed to the conversion system that can generate entities that eventually I don't use at all, so I would like to delete them or avoid to be created. I can't modify the prefabs (so I cannot use Convert To Entity Stop). However I could add Convert To Entity Stop at run time if it's the best thing to do. Suggestions? I was thinking about the GameObjectConversion groups, but not sure if this can be done.

 

StopConvertToEntity cannot be used for my case

 

As long as you have a way of knowing that an entity is one you don't need, then a GameObjectConversionSystem can definitely do this.

 

how though? Still figuring this out

 

How to know if an entity is one you don't need or how to write a GameObjectConversionSystem? I can't help you with the former, and the latter likely depends on how you do the former.

 

At this point in time I am trying to solving it querying all the entities that have ONLY these components:



and delete them. But I am not sure if it's possible to write a query that returns entities with only those components

 

You can mark all the entities for GameObjects you don't want in the GameObjectConversionSystem and then destroy them in a system later, but there's no way to keep them from being created at this point, as far as I can tell. As you've found, StopConvertToEntity only works for stuff in the scene.

 

You could try to write a conversion system in AfterConversionGroup (I forget names because I'm having tech issues on my workstation atm) which gets an EntityQuery from DstEntityManager querying for those components you specified, then doing chunk iteration checking the chunk's archetype. If the archetype is an exact match, you add it to a list to be destroyed. After iterating through the chunks, tell DstEntityManager to destroy your list of chunks.

I don't know if deleting entities like that breaks the mapping system. If it does, you're best bet is to remove all the components and add a DeleteMe tag so that the Entity technically still exists for the mapping system but the memory usage is drastically reduced.

 

Eventually the simplest solution was actually to remove the unused gameobjects from the prefabs before to convert and reassemble them back right after. I thought it was dangerous, but it seems to work fine.

 

I lately realised that prefab hierarchies cannot be changed, so the solution wasn't viable either. I had to use the ConvertScene to be able to use gameobjects as instance of prefab, so that I can change the hierarchy (purge invalid GOs)

Code (CSharp):

1.  var gos = new FasterList<GameObject>();
2.                 var temporaryScene = SceneManager.CreateScene("temporary");
3.                 SceneManager.SetActiveScene(temporaryScene);
4.  
5.                 for (var j = 0; j < prefabData.Count; ++j)
6.                 {
7.                     var transformParent = Object.Instantiate(loadTask.Result[j]);
8.  
9.                     gos.Add(transformParent);
10.  
11.                     Sanitize(transformParent);
12.                 }
13.  
14.                 var gameObjectConversionSettings =
15.                     GameObjectConversionSettings.FromWorld(physicsWorld, ECSPhysicResourceManager.Instance.blobStore);
16.  
17.                 gameObjectConversionSettings.ConversionWorldPreDispose += world =>
18.                     RelinkEntities(physicsWorld, world.GetExistingSystem<GameObjectConversionSystem>(), gos, prefabData);
19.  
20.                 GameObjectConversionUtility.ConvertScene(temporaryScene, gameObjectConversionSettings);
21.  
22.                 SceneManager.UnloadScene(temporaryScene);

With more insights I can say that there is no reason to not support the conversion of a provided array of GameObjects.

public void CreateEntitiesForGameObjects(Scene scene)

must have a version

public void CreateEntitiesForGameObjects(List<GameObjects> scene)

No reason to not have it really.