Investigate Observers

[mrchantey]

Bevy now has observers, this may be a better approach than change detection on sparse set tag components.

• Maybe easier to reason about in selectors?
• Instant effects, means no one frame delay

Option 1: Triggers for RunResult (partial adoption)

We could use trigger add/remove systems that run on some query like:

fn add_child_triggers(commands: Commands, parents: Query<&Children, Added<Running>>){
  for (parent, children) in parents.iter(){
    for child in children{
      commands.entity(parent).add_trigger::<RunResult>(child)
    }
  }
}

And i suppose something similar when it stops running..

Option 2: Triggers for RunResult and Running

Whenever children are added to a parent:

1. the child observes the parent 'StopRunning' and also stops running as a result
2. the parent observes the child 'StopRunning' and makes some decision or bubbles it up..
3. the parent can trigger 'StartRunning' on the child

[mrchantey]

done, fully integrated

[mgi388]

@mrchantey nice, is there a commit that fixes this? Can't see anything in https://github.com/mrchantey/beet/commits/main/

[mrchantey]

yeah sry should've closed with a pr, here it is #6