DeltaVR3DModelGeneration/Assets/_PROJECT/Scripts/ModeGeneration/ShapeDetection/TwoHandsScaleGrabInteractable.cs

using UnityEditor;
using UnityEngine;
using UnityEngine.XR.Interaction.Toolkit;

public class TwoHandScaleGrabInteractable : XRGrabInteractable
{
    [Header("Two-Hand Scaling")]
    public float minScale = 0.1f;
    public float maxScale = 5f;
    public float scaleLerpSpeed = 0f;

    private Transform scalingTransform;
    private float initialHandsDistance;
    private Vector3 initialScale;
    private bool twoHandsGrabbing;

    void Start()
    {
        selectMode = InteractableSelectMode.Multiple;
        useDynamicAttach = true;
        reinitializeDynamicAttachEverySingleGrab = false;

        scalingTransform = transform.GetChild(0);
    }

    protected override void OnSelectEntered(SelectEnterEventArgs args)
    {
        base.OnSelectEntered(args);
        UpdateTwoHandState();
    }

    protected override void OnSelectExited(SelectExitEventArgs args)
    {
        Debug.Log("current local scale: " + transform.localScale);
        base.OnSelectExited(args);
        UpdateTwoHandState();
    }

    void UpdateTwoHandState()
    {
        if (interactorsSelecting.Count >= 2)
        {
            var a = interactorsSelecting[0];
            var b = interactorsSelecting[1];

            var pA = a.GetAttachTransform(this).position;
            var pB = b.GetAttachTransform(this).position;

            initialHandsDistance = Vector3.Distance(pA, pB);
            initialScale = scalingTransform.localScale;
            twoHandsGrabbing = initialHandsDistance > 0.0001f;
        }
        else
        {
            twoHandsGrabbing = false;
        }
    }

    public override void ProcessInteractable(XRInteractionUpdateOrder.UpdatePhase updatePhase)
    {
        base.ProcessInteractable(updatePhase);

        if (!twoHandsGrabbing || interactorsSelecting.Count < 2 || initialHandsDistance <= 0.0001f)
            return;
        var a = interactorsSelecting[0];
        var b = interactorsSelecting[1];

        var pA = a.GetAttachTransform(this).position;
        var pB = b.GetAttachTransform(this).position;

        float current = Vector3.Distance(pA, pB);
        if (current <= 0.0001f)
            return;

        float ratio = current / initialHandsDistance;
        Debug.Log("distance ratio: " + ratio);

        Vector3 desired = initialScale * ratio;
        float uniform = Mathf.Clamp(desired.x, minScale, maxScale);
        desired = new Vector3(uniform, uniform, uniform);

        if (scaleLerpSpeed > 0f)
            desired = Vector3.Lerp(transform.localScale, desired, Time.deltaTime * scaleLerpSpeed);

        scalingTransform.localScale = desired;
    }
}