using UnityEngine;

public class OctoIkRaycast : MonoBehaviour
{
    public float _distance = 1;
    public Vector3 rotationOffset;
    public Transform _target;
    public LayerMask _layerMask;

    Vector3 originPos;
    Vector3 targetPos;
    Quaternion originRot;
    Quaternion targetRot;

    void Start()
    {
        originPos = targetPos = _target.localPosition;
        originRot = targetRot = _target.localRotation;
    }

    void Update()
    {
        float deltaPos = Time.deltaTime * 3f;
        float deltaRot = Time.deltaTime * 3f;

        RaycastHit hit;

        if (Physics.Raycast(transform.position, transform.TransformDirection(Vector3.forward), out hit, _distance, _layerMask))
        {
            Debug.DrawRay(transform.position, transform.TransformDirection(Vector3.forward) * hit.distance, Color.yellow);

            targetPos = transform.InverseTransformPoint(hit.point);
            targetRot = Quaternion.LookRotation(-transform.InverseTransformDirection(hit.normal), transform.up) * Quaternion.Euler(rotationOffset);

            deltaPos = Mathf.Lerp(1, deltaPos, Mathf.Clamp01(hit.distance / _distance));
            deltaRot = Mathf.Lerp(.1f, deltaRot, Mathf.Clamp01(hit.distance / _distance));
        }
        else
        {
            Debug.DrawRay(transform.position, transform.TransformDirection(Vector3.forward) * _distance, Color.white);

            targetPos = originPos;
            targetRot = originRot;
        }

        _target.localPosition = Vector3.Lerp(_target.localPosition, targetPos, deltaPos);
        _target.localRotation = Quaternion.Lerp(_target.localRotation, targetRot, deltaRot);
    }
}