Joystickエラーが出る

現状

前回使っていた時には使用できたのにaseetをインポートした瞬間からエラーになってしまっている

エラー文

Assets/Joystick Pack/Scripts/Base/Joystick.cs(69,19): error CS0029: Cannot implicitly convert type 'UnityEngine.Camera' to 'Camera'
Assets/Joystick Pack/Scripts/Base/Joystick.cs(71,68): error CS1503: Argument 1: cannot convert from 'Camera' to 'UnityEngine.Camera'

unityengine.cameraを暗黙的に変換できません

試したこと

プロジェクト新しいのを作ってインポート
アッセットのdemoも再生できない

該当スクリプト

unity
1using System.Collections;
2using System.Collections.Generic;
3using UnityEngine;
4using UnityEngine.EventSystems;
5
6public class Joystick : MonoBehaviour, IPointerDownHandler, IDragHandler, IPointerUpHandler
7{
8    public float Horizontal { get { return (snapX) ? SnapFloat(input.x, AxisOptions.Horizontal) : input.x; } }
9    public float Vertical { get { return (snapY) ? SnapFloat(input.y, AxisOptions.Vertical) : input.y; } }
10    public Vector2 Direction { get { return new Vector2(Horizontal, Vertical); } }
11
12    public float HandleRange
13    {
14        get { return handleRange; }
15        set { handleRange = Mathf.Abs(value); }
16    }
17
18    public float DeadZone
19    {
20        get { return deadZone; }
21        set { deadZone = Mathf.Abs(value); }
22    }
23
24    public AxisOptions AxisOptions { get { return AxisOptions; } set { axisOptions = value; } }
25    public bool SnapX { get { return snapX; } set { snapX = value; } }
26    public bool SnapY { get { return snapY; } set { snapY = value; } }
27
28    [SerializeField] private float handleRange = 1;
29    [SerializeField] private float deadZone = 0;
30    [SerializeField] private AxisOptions axisOptions = AxisOptions.Both;
31    [SerializeField] private bool snapX = false;
32    [SerializeField] private bool snapY = false;
33
34    [SerializeField] protected RectTransform background = null;
35    [SerializeField] private RectTransform handle = null;
36    private RectTransform baseRect = null;
37
38    private Canvas canvas;
39    private Camera cam;
40
41    private Vector2 input = Vector2.zero;
42
43    protected virtual void Start()
44    {
45        HandleRange = handleRange;
46        DeadZone = deadZone;
47        baseRect = GetComponent<RectTransform>();
48        canvas = GetComponentInParent<Canvas>();
49        if (canvas == null)
50            Debug.LogError("The Joystick is not placed inside a canvas");
51
52        Vector2 center = new Vector2(0.5f, 0.5f);
53        background.pivot = center;
54        handle.anchorMin = center;
55        handle.anchorMax = center;
56        handle.pivot = center;
57        handle.anchoredPosition = Vector2.zero;
58    }
59
60    public virtual void OnPointerDown(PointerEventData eventData)
61    {
62        OnDrag(eventData);
63    }
64
65    public void OnDrag(PointerEventData eventData)
66    {
67        cam = null;
68/////////////////////該当場所//////////////////////////////
69        if (canvas.renderMode == RenderMode.ScreenSpaceCamera)
70            cam = canvas.worldCamera;
71/////////////////////////////////////////////////////////////////
72        Vector2 position = RectTransformUtility.WorldToScreenPoint(cam, background.position);
73        Vector2 radius = background.sizeDelta / 2;
74        input = (eventData.position - position) / (radius * canvas.scaleFactor);
75        FormatInput();
76        HandleInput(input.magnitude, input.normalized, radius, cam);
77        handle.anchoredPosition = input * radius * handleRange;
78    }
79
80    protected virtual void HandleInput(float magnitude, Vector2 normalised, Vector2 radius, Camera cam)
81    {
82        if (magnitude > deadZone)
83        {
84            if (magnitude > 1)
85                input = normalised;
86        }
87        else
88            input = Vector2.zero;
89    }
90
91    private void FormatInput()
92    {
93        if (axisOptions == AxisOptions.Horizontal)
94            input = new Vector2(input.x, 0f);
95        else if (axisOptions == AxisOptions.Vertical)
96            input = new Vector2(0f, input.y);
97    }
98
99    private float SnapFloat(float value, AxisOptions snapAxis)
100    {
101        if (value == 0)
102            return value;
103
104        if (axisOptions == AxisOptions.Both)
105        {
106            float angle = Vector2.Angle(input, Vector2.up);
107            if (snapAxis == AxisOptions.Horizontal)
108            {
109                if (angle < 22.5f || angle > 157.5f)
110                    return 0;
111                else
112                    return (value > 0) ? 1 : -1;
113            }
114            else if (snapAxis == AxisOptions.Vertical)
115            {
116                if (angle > 67.5f && angle < 112.5f)
117                    return 0;
118                else
119                    return (value > 0) ? 1 : -1;
120            }
121            return value;
122        }
123        else
124        {
125            if (value > 0)
126                return 1;
127            if (value < 0)
128                return -1;
129        }
130        return 0;
131    }
132
133    public virtual void OnPointerUp(PointerEventData eventData)
134    {
135        input = Vector2.zero;
136        handle.anchoredPosition = Vector2.zero;
137    }
138
139    protected Vector2 ScreenPointToAnchoredPosition(Vector2 screenPosition)
140    {
141        Vector2 localPoint = Vector2.zero;
142        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(baseRect, screenPosition, cam, out localPoint))
143        {
144            Vector2 pivotOffset = baseRect.pivot * baseRect.sizeDelta;
145            return localPoint - (background.anchorMax * baseRect.sizeDelta) + pivotOffset;
146        }
147        return Vector2.zero;
148    }
149}
150
151public enum AxisOptions { Both, Horizontal, Vertical }