Detect hand touching objects

Setup Hand

To detect if the right hand is touching an object (e.g., A), both the right hand and object A need a Collider.

Setup hand collider

Under XROrigin > Right Hand > Right Hand Interaction Visual > R_Wrist, add an empty object. In this case, I named it ColliderBox

Choose the type of Collider that best surround the object. For the hand, I used Box Collider to cover the whole hand.

Here's what the collider looks like after configuration:

Setup RigidBody

Why do we need a RigidBody?

• If you want an object to participate in trigger events without physics interaction, you can use a collider with a Rigidbody set to Kinematic. This will allow the trigger events like OnTriggerEnter to work.
• If you want a completely static object that still participates in trigger events, you can use a collider without a Rigidbody, as long as the other object in the trigger has a Rigidbody.

By setting the Rigidbody to Kinematic and disabling Use Gravity, the hand can interact with trigger events while maintaining precise control of its movement.

Configuration Steps:

1. Add a Rigidbody to the hand's collider object (e.g., ColliderBox).
2. Set Use Gravity to unchecked.
3. Set the Rigidbody to Kinematic.

Repeat for the Left Hand

Follow the same steps to configure the left hand.

Setup Dog

Since the dog's body parts move independently, using a single collider (e.g., a bounding box around the entire body) may not work as expected when the dog changes poses (e.g., from standing to sitting). To address this:

1. Add colliders to individual body parts (e.g., Capsule Collider for the head, limbs, etc.).
2. Enable Is Trigger on each collider to allow OnTriggerEnter, OnTriggerStay, and OnTriggerExit events.
3. Assign the same tag (e.g., dog) to all colliders to detect them collectively as the "dog."

For example, here’s how the Capsule Collider around the dog's head is set up:

Scripts

Detect When the Hand Starts Touching the Dog

private float startTime = 0f;
void OnTriggerEnter(Collider collider)
{
    Debug.Log("Hand touching sth");
    if(collider.gameObject.CompareTag("dog"))
    {
        Debug.Log("Hand touching dog");
        startTime = Time.time;  
    }
}

Detect if the Hand Stays Touching the Dog for 5 Seconds

void OnTriggerStay(Collider collider)
{   
    if(collider.gameObject.CompareTag("dog"))
    {
        // gloveController.PlayHapticFeedback();
        gloveController.PlayHapticFeedback();
        Debug.Log("Hand stay touching dog");
        float elapsedTime = Time.time - startTime;
        if (elapsedTime > 2f)
        {
            Debug.Log("User has petted dog for more than 5 seconds!");
            // uiPrompt.SetActive(true);
            animator.SetBool("idle", true);

            if(sequenceHandler.GetIsWaitingForPetting()){
                sequenceHandler.IncrementStateIndex();
            }
        }
    }
}

Detect When the Hand Stops Touching the Dog

void OnTriggerExit(Collider collider)
{
    Debug.Log("Hand leaving sth");
    if(collider.gameObject.CompareTag("dog"))
    {
        startTime = 0;
        Debug.Log("Hand leaving dog");
        animator.SetBool("idle", false);
    }
}

Key Notes:

1. Colliders: Ensure the colliders for the hand and the dog's body parts are properly aligned and scaled to avoid false positives or missed collisions.
2. Rigidbodies: At least one of the objects involved in the trigger (hand or dog) must have a Rigidbody for the trigger events to work.
3. Tags: Use consistent and specific tags (e.g., dog) to simplify collision detection logic.