ScienceLab.FrictionForce/Assets/Scripts/CursorController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CursorController : MonoBehaviour
{
    [SerializeField] private Texture2D _defaultCursor;
    [SerializeField] private Texture2D _pickCursor;
    [SerializeField] private Texture2D _placeCursor;
    [SerializeField] private Texture2D _chalkCursor;
    [SerializeField] private float _interactionDistance = 3f;
    [SerializeField] private Camera _camera;
    [SerializeField] private float _holdDistance = 1f;
    [SerializeField] private float _followSpeed = 12f;

    private GameObject _heldObject;
    private Rigidbody _heldRigidbody;
    private Collider _heldCollider;
    private ChalkDrawer _chalkDrawer;

    private void Start()
    {
        Cursor.lockState = CursorLockMode.Confined;
        Cursor.visible = true;
        SetCursor(_defaultCursor);
        _chalkDrawer = GetComponent<ChalkDrawer>();
    }

    private void Update()
    {
        if (_chalkDrawer != null && _chalkDrawer.IsHoldingChalk)
            return;

        if (Input.GetMouseButtonDown(1))
        {
            NoteBookController nb = FindOpenNotebook();
            if (nb != null) { nb.CloseNotebook(); return; }
        }

        HandleRaycast();
        HandleHeldObject();
        ForceEnableColliders();
    }

    private NoteBookController FindOpenNotebook()
    {
        GameObject[] notes = GameObject.FindGameObjectsWithTag("Note");
        foreach (var n in notes)
        {
            NoteBookController nb = n.GetComponent<NoteBookController>();
            if (nb != null && nb.IsOpen) return nb;
        }
        return null;
    }

    private void ForceEnableColliders()
    {
        if (_heldObject != null) return;

        GameObject[] targets = GameObject.FindGameObjectsWithTag("Target");
        foreach (GameObject target in targets)
        {
            Collider col = target.GetComponent<Collider>();
            if (col == null) col = target.GetComponentInChildren<Collider>();
            if (col != null && !col.enabled)
            {
                col.enabled = true;
                Rigidbody rb = target.GetComponent<Rigidbody>();
                if (rb != null) rb.WakeUp();
            }
        }
    }

    private void HandleRaycast()
    {
        if (FindOpenNotebook() != null) return;

        Ray ray = _camera.ScreenPointToRay(Input.mousePosition);

        RaycastHit[] hits = Physics.SphereCastAll(ray, 0.25f, _interactionDistance);
        foreach (RaycastHit h in hits)
        {
            if (h.collider.CompareTag("Chalk"))
            {
                SetCursor(_chalkCursor);
                if (Input.GetMouseButtonDown(0) && _chalkDrawer != null)
                    _chalkDrawer.PickupChalk(h.collider.gameObject);
                return;
            }

            if (h.collider.CompareTag("Towel"))
            {
                SetCursor(_chalkCursor);
                if (Input.GetMouseButtonDown(0) && _chalkDrawer != null)
                    _chalkDrawer.PickupTowel(h.collider.gameObject);
                return;
            }

            if (h.collider.CompareTag("Note"))
            {
                SetCursor(_chalkCursor);
                if (Input.GetMouseButtonDown(0))
                {
                    NoteBookController nb = h.collider.GetComponent<NoteBookController>();
                    if (nb != null) nb.OpenNotebook();
                }
                return;
            }
        }

        if (_heldObject != null)
        {
            if (Physics.Raycast(ray, out RaycastHit hit, _interactionDistance * 3f, Physics.DefaultRaycastLayers, QueryTriggerInteraction.Ignore))
            {
                if (hit.collider.CompareTag("Shelf"))
                {
                    SetCursor(_placeCursor);
                    if (Input.GetMouseButtonDown(0))
                    {
                        Transform place = hit.collider.transform.Find("Place");
                        if (place != null)
                        {
                            Collider placeCollider = place.GetComponent<Collider>();
                            if (placeCollider != null)
                                PlaceObject(placeCollider);
                        }
                    }
                    return;
                }

                if (hit.collider.CompareTag("Scale"))
                {
                    SetCursor(_placeCursor);
                    if (Input.GetMouseButtonDown(0))
                    {
                        Transform platform = hit.collider.transform.Find("platform");
                        if (platform != null)
                        {
                            Collider platformCollider = platform.GetComponent<Collider>();
                            if (platformCollider != null)
                                PlaceOnScale(platformCollider);
                        }
                    }
                    return;
                }
            }

            SetCursor(_pickCursor);
            if (Input.GetMouseButtonDown(0))
                DropObject();
            return;
        }

        if (Physics.Raycast(ray, out RaycastHit hitTarget, _interactionDistance, Physics.DefaultRaycastLayers, QueryTriggerInteraction.Ignore))
        {
            if (hitTarget.collider.CompareTag("Target"))
            {
                SetCursor(_pickCursor);
                if (Input.GetMouseButtonDown(0))
                    PickUpObject(hitTarget.collider.gameObject);
                return;
            }
        }

        SetCursor(_defaultCursor);
    }

    private void PlaceOnScale(Collider platformCollider)
    {
        if (_heldObject == null) return;

        Bounds b = platformCollider.bounds;
        Collider objCollider = _heldObject.GetComponent<Collider>();
        if (objCollider == null)
            objCollider = _heldObject.GetComponentInChildren<Collider>();

        float objectHeight = objCollider != null ? objCollider.bounds.extents.y : 0.1f;
        _heldObject.transform.position = new Vector3(b.center.x, b.max.y + objectHeight, b.center.z);

        if (_heldCollider != null) _heldCollider.enabled = true;
        if (_heldRigidbody != null) { _heldRigidbody.useGravity = true; _heldRigidbody.WakeUp(); }

        _heldObject = null;
        _heldRigidbody = null;
        _heldCollider = null;
        SetCursor(_defaultCursor);
    }

    private void HandleHeldObject()
    {
        if (_heldObject == null) return;

        Ray ray = _camera.ScreenPointToRay(Input.mousePosition);
        Vector3 targetPosition;

        if (Physics.Raycast(ray, out RaycastHit hit, _holdDistance))
            targetPosition = hit.point - ray.direction * 0.15f;
        else
            targetPosition = ray.origin + ray.direction * _holdDistance;

        _heldObject.transform.position = Vector3.Lerp(
            _heldObject.transform.position,
            targetPosition,
            Time.deltaTime * _followSpeed
        );
    }

    private void PickUpObject(GameObject obj)
    {
        _heldObject = obj;
        _heldRigidbody = obj.GetComponent<Rigidbody>();
        _heldCollider = obj.GetComponent<Collider>();
        if (_heldCollider == null) _heldCollider = obj.GetComponentInChildren<Collider>();

        if (_heldRigidbody != null)
        {
            _heldRigidbody.WakeUp();
            _heldRigidbody.useGravity = false;
            _heldRigidbody.velocity = Vector3.zero;
            _heldRigidbody.angularVelocity = Vector3.zero;
        }

        if (_heldCollider != null) _heldCollider.enabled = false;
    }

    private void PlaceObject(Collider placeCollider)
    {
        if (_heldObject == null) return;

        Bounds b = placeCollider.bounds;
        Collider objCollider = _heldObject.GetComponent<Collider>();
        if (objCollider == null) objCollider = _heldObject.GetComponentInChildren<Collider>();

        float objectHeight = objCollider != null ? objCollider.bounds.extents.y : 0.1f;
        _heldObject.transform.position = new Vector3(b.center.x, b.max.y + objectHeight, b.center.z);

        if (_heldCollider != null) _heldCollider.enabled = true;
        if (_heldRigidbody != null) { _heldRigidbody.useGravity = true; _heldRigidbody.WakeUp(); }

        _heldObject = null;
        _heldRigidbody = null;
        _heldCollider = null;
        SetCursor(_defaultCursor);
    }

    private void DropObject()
    {
        if (_heldCollider != null) _heldCollider.enabled = true;
        if (_heldRigidbody != null) { _heldRigidbody.useGravity = true; _heldRigidbody.WakeUp(); }

        _heldObject = null;
        _heldRigidbody = null;
        _heldCollider = null;
        SetCursor(_defaultCursor);
    }

    private void SetCursor(Texture2D cursor)
    {
        Cursor.SetCursor(cursor, new Vector2(16, 16), CursorMode.Auto);
    }
}