小地图的算法

昨天研究了下小地图论坛上的代码看不懂，主要是算法，求大神解释

@script ExecuteInEditMode()
public var Enemy_ : Texture; //define enemy texture
public var Box_:Texture;//define the box texture
public var Player_:Texture;//define player texture
public var radarBG : Texture; //small map texture
public var centerObject : Transform; //chracter position
public var mapScale = 0.3; //地圖縮放
public var mapCenter = Vector2(50,50); //地圖中心
function OnGUI () {
  
    bX=centerObject.transform.position.x * mapScale;
    bY=centerObject.transform.position.z * mapScale;
      
    bX=centerObject.transform.position.x * mapScale;
    bY=centerObject.transform.position.z * mapScale;
      
    GUI.DrawTexture(Rect(mapCenter.x-55,mapCenter.y-50,128,128),radarBG);
   // 上面的mapCenter.x-32是地圖的x位置，mapCenter.y-32是y位置，64,64是地圖的大小
    DrawBlipsForEnemies();
        DrawBlipsForPlayer();
        DrawBlipsForBox();
}
function DrawBlipsForBox(){ //draw box texture in small map
  
    var gos : GameObject[];
    gos = GameObject.FindGameObjectsWithTag("Box");
    var distance = Mathf.Infinity;
    var position = transform.position;
    for (var go : GameObject in gos)  {
        drawBlip(go,Box_);
    }
}
function DrawBlipsForPlayer(){ //draw player texture in small map
  
    var gos : GameObject[];
    gos = GameObject.FindGameObjectsWithTag("Player");
    var distance = Mathf.Infinity;
    var position = transform.position;
    for (var go : GameObject in gos)  {
        drawBlip(go,Player_);
    }
}
function DrawBlipsForEnemies(){ //draw enemy texture in small map
  
    var gos : GameObject[];
    gos = GameObject.FindGameObjectsWithTag("Enemy");
    var distance = Mathf.Infinity;
    var position = transform.position;
    for (var go : GameObject in gos)  {
    drawBlip(go,Enemy_);
    }
}
function drawBlip(go,aTexture){ //draw position in small map
  
    centerPos=centerObject.position;
    extPos=go.transform.position;
  
    dist=Vector3.Distance(centerPos,extPos);
   
    dx=centerPos.x-extPos.x;
    dz=centerPos.z-extPos.z;
  
    deltay=Mathf.Atan2(dx,dz)*Mathf.Rad2Deg - 270 - centerObject.eulerAngles.y;
  
    bX=dist*Mathf.Cos(deltay * Mathf.Deg2Rad);
    bY=dist*Mathf.Sin(deltay * Mathf.Deg2Rad);
  
    bX=bX*mapScale;
    bY=bY*mapScale;
  
    if(dist<=200){
       GUI.DrawTexture(Rect(mapCenter.x+bX,mapCenter.y+bY,16,16),aTexture);
    }
}