Drop zone not setting object to Kinematic

mdyer43

I have an object start in another drop zone and that works just fine. When I remove it from that drop zone and place it in another it falls out. And the rigidbody.iskinematic is never set to true again. I've changed from drop zone style kinematic to parenting and neither worked.

mdyer43

Using Unity Engine 2019.3

MarshallVisions

I'm having the exact same problem. Jointed drop zones are the only ones working for me.

PizzaPopcorn

Hi there!
If you are still looking for a solution I managed to make a workaround.

First let me explain what happened.
After debugging and stack-tracing the code, I found that snaps force unsnap immediately because OnTriggerExit is being called. Now, why is this happening? It turns out that in Unity 2019.3 (and higher I think), changing the isKinematic value triggers OnTriggerExit and OnTriggerEnter events, so that automatically calls the ForceUnsnap method.

My workaround consists in creating a bool variable called "inSnapProcess", and I set it to true at the start of UpdateTransformDimensions coroutine, and I set it back to false again at the end after waiting two frames (less delay won't work) and then add a validation with this value to the CheckCanUnsnap method and that's it.

Here is the code for UpdateTransformDimensions:

bool inSnapProcess;
protected virtual IEnumerator UpdateTransformDimensions(VRTK_InteractableObject ioCheck, GameObject endSettings, Vector3 endScale, float duration)
        {
            inSnapProcess = true;
            float elapsedTime = 0f;
            Transform ioTransform = ioCheck.transform;
            Vector3 startPosition = ioTransform.position;
            Quaternion startRotation = ioTransform.rotation;
            Vector3 startScale = ioTransform.localScale;
            bool storedKinematicState = ioCheck.isKinematic;
            ioCheck.isKinematic = true;
            while (elapsedTime <= duration)
            {
                elapsedTime += Time.deltaTime;
                if (ioTransform != null && endSettings != null)
                {
                    ioTransform.position = Vector3.Lerp(startPosition, endSettings.transform.position, (elapsedTime / duration));
                    ioTransform.rotation = Quaternion.Lerp(startRotation, endSettings.transform.rotation, (elapsedTime / duration));
                    ioTransform.localScale = Vector3.Lerp(startScale, endScale, (elapsedTime / duration));
                }
                yield return null;
            }

            if (ioTransform != null && endSettings != null)
            {
                //Force all to the last setting in case anything has moved during the transition
                ioTransform.position = endSettings.transform.position;
                ioTransform.rotation = endSettings.transform.rotation;
                ioTransform.localScale = endScale;
            }

            ioCheck.isKinematic = storedKinematicState;
            SetDropSnapType(ioCheck);

            yield return null;
            yield return null;

            inSnapProcess = false;
        }

Code for CheckCanUnsnap:

protected virtual void CheckCanUnsnap(VRTK_InteractableObject interactableObjectCheck)
        {
            if (interactableObjectCheck != null && currentValidSnapInteractableObjects.Contains(interactableObjectCheck) && ValidUnsnap(interactableObjectCheck) && !inSnapProcess)
            {
                if (isSnapped && currentSnappedObject == interactableObjectCheck)
                {
                    ForceUnsnap();
                }

                RemoveCurrentValidSnapObject(interactableObjectCheck);

                if (!ValidSnappableObjectIsHovering())
                {
                    ToggleHighlight(interactableObjectCheck, false);
                    willSnap = false;
                }

                interactableObjectCheck.SetSnapDropZoneHover(this, false);

                if (ValidSnapObject(interactableObjectCheck, true))
                {
                    ToggleHighlightColor();
                    OnObjectExitedSnapDropZone(SetSnapDropZoneEvent(interactableObjectCheck.gameObject));
                }
            }
        }

Hope it works for you guys!