Provide a StateChanged event in the ManipulationHandler

[camnewnham]

Describe the problem

PhysX.Bake gets called when scaling objects. When object colliders have high vertex counts (i.e. a convex mesh collider created from a CAD model), it is advantageous to disable the collider when scaling begins, and reapply it when it finishes to avoid this massive performance hit.

Describe the solution you'd like

A UnityEvent exposed when the state is changed, or even simply an editor toggle to disable the collider when scaling begins and re-enable it when it ends. Or both.

Describe alternatives you've considered

Copying and customizing the ManipulationHandler, making the State class public and providing an event triggered by the setter. https://gist.github.com/camnewnham/86da46211982b07c28d1be3e9dfa4ba9. Relevant lines:

        public event Action<State, State> CurrentStateChanged;
        public State CurrentState
        {
            get
            {
                return _currentState;
            }
            set
            {
                if (_currentState != value)
                {
                    CurrentStateChanged?.Invoke(_currentState, value);
                    _currentState = value;
                }
            }
        }

        private void _OnCurrentStateChanged(MyManipulationHandler.State oldstate, MyManipulationHandler.State newstate)
        {
            if (!oldstate.HasFlag(MyManipulationHandler.State.Scaling) && newstate.HasFlag(MyManipulationHandler.State.Scaling))
            {
                _meshCollider = this.GetComponent<MeshCollider>();
                if (_meshCollider != null && _meshCollider.enabled)
                {
                    _meshCollider.enabled = false;
                }
            }
            else if (oldstate.HasFlag(MyManipulationHandler.State.Scaling) && !newstate.HasFlag(MyManipulationHandler.State.Scaling))
            {
                if (_meshCollider != null && !_meshCollider.enabled)
                {
                    _meshCollider.enabled = true;
                }
            }
        }

Additional context

Reproduced for Julia at Hack Week.

[Zee2]

Looking through backlog; is this specifically for ManipulationHandler or is for ObjectManipulator? We've deprecated ManipulationHandler for ObjectManipulator, so should this be closed won't-fix?

[IssueSyncBot]

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