/////////////////////////////////////////////////////////////////////////////////////////////////////////
#region LOS视线检测相关
//---------------------------------------------------------------------------------------------------------
//松弛疗法，微调pos，直到该点真正地处于某个多边形中为止
//【遗留问题】没有考虑松弛过程中发生进入不可进入区域的情况
Belong_Status RelaxPostion(ref Vector2 pos, out Polygon poly)
{
Vector2 p = pos;
Object obj = null;
Belong_Status ret = GetPointLocation(p, out obj); //第一次
if (ret == Belong_Status.Invalid)
{
poly = null;
return(ret); //不用松弛了，直接返回
}
Random rand = new Random((int)DateTime.Now.Ticks);
bool ok = (ret == Belong_Status.Polygon);
while (!ok)
{
p.X = pos.X + (float)(rand.NextDouble() - 0.5d) / 10f;
p.Y = pos.Y + (float)(rand.NextDouble() - 0.5d) / 10f;
ret = GetPointLocation(p, out obj);
ok = (ret == Belong_Status.Polygon);
}
pos = p;
poly = (Polygon)obj;
return(ret);
}
//点与单个多边形的关系检测
//- 如果点在多边形内部，retobj返回该多边形
//- 如果点在多边形的边上，retobj返回该边
//- 如果点在多边形的顶点上，retobj返回该点
//- 如果点在多边形之外，retobj返回null
public Belong_Status PointPolygonRelationshipTest(Vector2 pos, Polygon poly, out Object retobj)
{
//默认情况：点处于多边形以内
retobj = poly;
Belong_Status result = Belong_Status.Polygon;
foreach (Edge e in poly.edges)
{
Vector2 between = new Vector2(e.to.x - e.from.x, e.to.y - e.from.y);
Vector2 from = new Vector2(pos.X - e.from.x, pos.Y - e.from.y);
float test = Vector2.Ccw(between, from);
if (FloatEqual(test, 0)) //在边上或在顶点上
{
Vector2 to = new Vector2(pos.X - e.to.x, pos.Y - e.to.y);
if (FloatEqual(from.LengthSq(), 0)) //在顶点e.from上
{
retobj = e.from;
result = Belong_Status.Vertex;
}
else if (FloatEqual(to.LengthSq(), 0)) //在顶点e.to上
{
retobj = e.to;
result = Belong_Status.Vertex;
}
else //在边上
{
retobj = e;
result = Belong_Status.Edge;
}
break;
}
if (test < 0) //点处于polygon之外
{
retobj = null;
result = Belong_Status.OutOfPolygon;
break;
}
}
return(result);
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////
#region 快速检测点处于哪个多边形中
//快速检测点的位置
//- retobj: 要么返回一个多边形，要么返回一条边，要么返回一个点
//- 返回值: true，成功检测出了点的位置；false，点处于不合法位置
public Belong_Status GetPointLocation(Vector2 p, out Object retobj)
{
retobj = null;
Belong_Status ret = Belong_Status.Invalid;
for (int i = 0; i < polys.Length; i++)
{
Polygon poly = polys[i];
if ((p.X >= poly.min.X && p.X <= poly.max.X) &&
(p.Y >= poly.min.Y && p.Y <= poly.max.Y))
{
Object obj;
Belong_Status result = PointPolygonRelationshipTest(p, poly, out obj);
if (result == Belong_Status.Polygon)
{
ret = result; retobj = obj;
Debug.WriteLine(string.Format("(点位置检测) P:{0}", poly.idx));
break;
}
else if (result == Belong_Status.Edge)
{
ret = result; retobj = obj;
Edge e = (Edge)obj;
Debug.WriteLine(string.Format("(点位置检测) P:{0} E:({1}-{2})", poly.idx, e.belong_poly, e.neighbor_poly));
break;
}
else if (result == Belong_Status.Vertex)
{
ret = result; retobj = obj;
FPoint pos = (FPoint)obj;
Debug.WriteLine(string.Format("(点位置检测) P:{0} V:({1},{2})", poly.idx, pos.x, pos.y));
break;
}
}
}
return(ret);
}
