That would be really expensive for anything like me.ParticleContainer. I think the reason we don't want to recompute child bounds automatically is because children are free to move independently.

good point, I forgot about it. Although we could make it a user configurable option through a boolean flag, and being disable by default. this solves the root container scenario and the particle container, while allowing the user to enable it when needed for child container(s).

You mean having an extra rect in the space invaders tutorial? https://github.com/melonjs/tutorial-space-invaders/blob/gh-pages/tutorial_step5/js/enemy_manager.js#L7

I'm fine with it, as it's more "special" behaviour, and is easily dictated in what's going on. I think too many settings complicates the system.

@agmcleod I actually removed the local copy of chidBounds you added in the enemy manager : melonjs/tutorial-space-invaders@84458ec?diff=unified#diff-55e845ee3be24edb5008664636b102d0L7

but what I was suggesting is to also remove childBounds from the me.Container implementation and directly use the bounds rect inherited from the me.Renderable object. As i was saying having two different rect is not really useful

I think we're coming full-circle on this issue. We've had discussions in the past about the me.Container architecture in relation to its bounding boxes.

Here are a few considerations off the top of my head:

• Container bounds should not be adjusted automatically.
  • Performance implications, especially with particle containers.
  • Impossible to statically size a container, e.g. a TMX map implemented as a container.
    • Breaks the concept of clipping children to the container bounds. See #692
• Caching the union of all children's bounding boxes must be a manual (explicit) request.
  • Using the container's own bounds for this cache will have unintended side effects, e.g. clipping.
  • Storing the cache in a separate rect is perhaps inconvenient, but at least its behavior is well defined and understood.

so I wanted to come back on this one. Can't we define some flag, that define if bounds should be automatically updated ? it would then be on by default for anything, except container ?

I really dislike this double bounds objects in container, and it just adds extra complexity to everything.