Bug Unity crashes after ~950 entities parented to previous entity

There appears to be a bug with parenting entities using the TransformSystem: when I create M entities, where entity N is parented to the entity N-1, Unity crashes after about 950 entities created.

 

Do you mean you create a parent-child hierarchy that is 950 deep, or 950 children on a parent? The latter works without issues for me.

 

The parent-child hierarchy is 950 deep in my case.

 

Which is ridiculous by the way. If they're not static and you have a bunch of these the cost to updating the local to world transforms for the deep children is going to blow out. Hierarchy optimization is about trying to keep it as flat as possible!

 

Not quite sure (long time since I checked) but the Transform system might be implemented in a recursive way instead of iterative, in which case probably the stack explodes after 950 recursive function calls.

Edit: LocalToParentSystem.cs, recursive call of ChildLocalToWorld:

Code (CSharp):

1.  void ChildLocalToWorld(float4x4 parentLocalToWorld, Entity entity, bool updateChildrenTransform)
2. {
3.      [...]
4.      if (ChildFromEntity.HasComponent(entity))
5.      {
6.           var children = ChildFromEntity[entity];
7.           for (int i = 0; i < children.Length; i++)
8.           {
9.                ChildLocalToWorld(localToWorldMatrix, children[i].Value, updateChildrenTransform);
10.           }
11.       }
12. }
13.  

 

Nothing in my game is static. The depth of the tree will depend on what my players create. I expect the general case will be (far) below such a ridiculous depth... but I can't have the game crashing when a player comes up with something wild!

Lol. That most certainly explains!

I'm going to bypass Unity's TransformSystem for now, since the only thing I really need is the transforms of children responding to changes in their parent(s), which I've now achieved with a custom system.