迷雾系统-1 地图及其区块

创建UGUI地图,每块地块（Image）上添加AreaNode脚本，根据PolygonCollider2D可视化编辑碰撞体形状，并以此生成Mesh

Mc_AreaNode脚本：

    private GameObject _objPrefab; //创建的Mesh预制体
    private float _canvasPosZ;
    private Vector3 _scale;
    public GameObject creatObj; //实例化出来的Mesh
    public Material mat;  //实例化的Mesh的Mat

    private PolygonCollider2D _collider;
    private Mesh _colliderMesh;
    private List<Vector2> _currentPoints = new List<Vector2>();
    private List<Vector2> _tempPoints = new List<Vector2>();
    private Vector3 _currentPosition;
      
    public void SetPrefab(GameObject prefab,float z,Vector3 scale)
    {
        _objPrefab = prefab;
        _canvasPosZ = z;
        _scale = scale;
    }
    
    public void CreatMesh(Action click=null)
    {
        RefreshMesh();
        creatObj = Instantiate(_objPrefab);
        creatObj.transform.localPosition = new Vector3(0f, 0f, _canvasPosZ - 1f);
        creatObj.GetComponent<MeshCollider>().sharedMesh = _colliderMesh;
        creatObj.GetComponent<MeshFilter>().mesh = _colliderMesh;
        creatObj.GetComponent<Mc_AreaMesh>().SetCallBack(click);
        creatObj.transform.localScale = _scale;
        mat = creatObj.GetComponent<MeshRenderer>().material;
    }

    private void Awake()
    {
        _collider = GetComponent<PolygonCollider2D>();
    }
    
    private void OnDrawGizmos()
    {
        RefreshMesh();
        if (_colliderMesh)
        {
            Gizmos.color = new Color32(212, 199, 21, 128);
            Gizmos.DrawMesh(_colliderMesh);
            Gizmos.color = Color.white;
        }
    }

    public int GetMine()
    {
        return mineNum;
    }

    private void RefreshMesh()
    {
        if (!_collider) return;
        
        bool recreateMesh = false;
        do
        {
            if (!_colliderMesh)
            {
                recreateMesh = true;
                break;
            }
            
            if (transform.position != _currentPosition)
            {
                recreateMesh = true;
                _currentPosition = transform.position;
                break;
            }
            
            _tempPoints.Clear();
            _collider.GetPath(0, _tempPoints);
            if (_tempPoints.Count != _currentPoints.Count)
            {
                recreateMesh = true;
                _currentPoints.Clear();
                _currentPoints.AddRange(_tempPoints);
                break;
            }
            
            for (int i = 0; i < _tempPoints.Count; ++i)
            {
                if (_tempPoints[i] != _currentPoints[i])
                {
                    recreateMesh = true;
                    _currentPoints.Clear();
                    _currentPoints.AddRange(_tempPoints);
                    break;
                }
            }
        } while (false);
        
        if (recreateMesh)
        {
            _colliderMesh = _collider.CreateMesh(true, true);
            _colliderMesh.RecalculateNormals();
            _colliderMesh.UploadMeshData(true);
        }
    }

生成Mesh的预制体，使用的材质球是Unlit/Color,这种材质球就不受光照影响，最开始设置为黑色
创建一个摄像机，专门照射生成的Mesh的层级，创建一个renderTexture,将摄像机设置为此RenderTexture,黑雾，创建一个Shader，当像素点为红色时，此像素点位透明，将材质球设置为黑雾（image）的材质球（点亮地块就将Mesh变为红色）

shader

Shader "Unlit/FogOfWar"
{
     Properties
    {
        _MainTex ("Main Texture", 2D) = "white" {}
       // _FogText("Fog Texture",2D) ="white" {}
        _alpha("alpah",float) = 0.02
    }
    SubShader
    {
        Blend SrcAlpha OneMinusSrcAlpha
        Tags
        {
            "Queue" = "Transparent"
        }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            sampler2D _MainTex;
            float _alpha;
          //  sampler2D _FogText;

            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv);
               // fixed4 fogCol =  tex2D(_FogText, i.uv);
                //红色是走过的路径，蓝色是当前人的视野范围
                // red = 1,blue=1,我们显示完全透明的黑色
                // red =1,blue=0，我们显示半透明黑色，表示走过，但是现在不在这个位置
                //red=0,blue=0,我们显示不透明的黑色
                //任何超过一的h值都会变成1
                 col.a = 1-col.r;
                return fixed4(0,0,0,col.a-_alpha);
            }
            ENDCG
        }
    }
}