Bevy overwrites unconditionally user `Transform`

[nicopap]

Problem: When I write to the Transform of a UI node, it doesn't do anything and I see no error messages.

Why this happens is fairly trivial: Transform is updated by the UI system in PostUpdate, and overwrites the user-set value unconditionally.

This is also true of AnimationClips. A system overwrites bone transforms targeted by an animations in PostUpdate. Even if the AnimationClip is paused!

What solution would I like

We should detect "Write-only" systems and emit an error message when users write to a component that is later accessed by a write-only system.

Future potential

We could extend this to GlobalTransform, or ComputedVisibilty and enable writing to those, since now we are capable to emit an error message with 0 overhead if they are misused.

[Aultus-defora]

We should detect "Write-only" systems and emit an error message when users write to a component that is later accessed by a write-only system.

That should only be true if the next system completely owerwrites component, instead of modifying it. Which in this case it will be...

[nicopap]

Check out the RFC

• Write only world query rfcs#71