private VoronoiCell FindCircumferencePolygon(Point point, out PointPolygonRelation relation)
{
for (int i = 0; i < polygons.Count; i++)
{
VoronoiCell result = GetPolygon(polygons[i].GetHashCode());
PointPolygonRelation tempValue = result.GetRelationTo(point);
if (tempValue == PointPolygonRelation.Out)
{
continue;
}
else
{
relation = tempValue;
return(result);
}
}
throw new NotImplementedException();
}
public static PointPolygonRelation CalcPointPolygonRelation(double x, double y, IList polygon)
{
if (polygon.Count < 3)
{
return(PointPolygonRelation.OutOfPolygon);
}
IVector start = (IVector)polygon[polygon.Count - 2];
if (start == null)
{
return(PointPolygonRelation.OutOfPolygon);
}
IVector middle = (IVector)polygon[polygon.Count - 1];
IVector end;
PointPolygonRelation result = PointPolygonRelation.OutOfPolygon;
int num = 0;
double minX, minY, maxX, maxY;
for (int i = 0; i < polygon.Count; i++, start = middle, middle = end)
{
end = (IVector)polygon[i];
//如果点刚好在顶点上，则直接返回
if ((x == start.X && y == start.Y) || (x == middle.X && y == middle.Y) || (x == end.X && y == end.Y))
{
result = PointPolygonRelation.OnPolygonVertex;
goto Return;
}
if (middle.X == end.X && middle.Y == end.Y)
{
continue;
}
minX = Math.Min(middle.X, end.X);
maxX = Math.Max(middle.X, end.X);
//如果X不落在最大X值和最小X值之间，则跳过
if (x > maxX || x < minX)
{
continue;
}
minY = Math.Min(middle.Y, end.Y);
maxY = Math.Max(middle.Y, end.Y);
//如果Y大于最大Y值则跳过，因为向上做射线不可能相交
if (y > maxY)
{
continue;
}
if (minX == maxX)//需要判断相交的线段为Y轴平行线
{
if (y > minY && y < maxY)
{
result = PointPolygonRelation.OnPolygonBorder;
goto Return;
}
else if (y < minY)//如果在最小的Y之下，因为目标线段为Y轴平行线，所以记为1次
{
num++;
}
}
else
{
double k = (middle.Y - end.Y) / (middle.X - end.X);
double b = middle.Y - k * middle.X;
double crossY = k * x + b;
if (crossY < y)
{
continue; //如果交点小于y则跳过，因为我们是向上做射线
}
if (crossY == y)
{
result = PointPolygonRelation.OnPolygonBorder;
goto Return;
}
if (x == maxX || x == minX)
{
if ((start.X > middle.X && end.X < middle.X) || (start.X < middle.X && end.X > middle.X))
{
num++;
}
}
else
{
num++;
}
}
}
if (num % 2 != 0)
{
result = PointPolygonRelation.InPolygon;
}
Return:
return(result);
}
