/// <summary>
/// 判断复合多边形是否部分或者完全位于矩形盒内
/// </summary>
/// <returns></returns>
public static bool IsMultiPolygonPartiallyWithinBox(WEMultiPolygon multiPolygon, WERectangle box)
{
WERectangle multipolygonBox = multiPolygon.MBR; //矩形盒不相交
if (!IsTwoBoxesIntersect(multipolygonBox, box))
{
return(false);
}
int sPolygonCount = multiPolygon.Polygons.Count();
for (int j = 0; j < sPolygonCount; j++) //遍历每个简单多边形判断是否有顶点位于矩形盒内
{
WEPolygon thisPolygon = (WEPolygon)multiPolygon.GetPolygon(j);
int sPointCount = thisPolygon.PointCount;
for (int i = 0; i < sPointCount; i++)
{
if (IsPointInBox(thisPolygon.Points[i], box))
{
return(true);
}
}
}
WEPoint LeftTop = new WEPoint(box.MinX, box.MaxY);
WEPoint LeftBottom = new WEPoint(box.MinX, box.MinY);
WEPoint RightTop = new WEPoint(box.MaxX, box.MaxY);
WEPoint RightBottom = new WEPoint(box.MaxX, box.MinY);
//判断矩形盒是否有顶点位于复合多边形内
if (IsPointInMultiPolygon(LeftTop, multiPolygon) || IsPointInMultiPolygon(LeftBottom, multiPolygon) ||
IsPointInMultiPolygon(RightBottom, multiPolygon) || IsPointInMultiPolygon(RightTop, multiPolygon))
{
return(true);
}
for (int j = 0; j < sPolygonCount; j++) //遍历每个简单多边形判断是否有边与矩形盒相交
{
WEPolygon thisPolygon = (WEPolygon)multiPolygon.GetPolygon(j);
int sPointCount = thisPolygon.PointCount;
WEPoint startPoint, endPoint;
for (int i = 0; i < sPointCount - 1; i++)
{
startPoint = thisPolygon.Points[i];
endPoint = thisPolygon.Points[i + 1];
if (IsSegmentIntersectsBox(startPoint, endPoint, box))
{
return(true);
}
}
startPoint = thisPolygon.Points[sPointCount - 1];
endPoint = thisPolygon.Points[0];
if (IsSegmentIntersectsBox(startPoint, endPoint, box))
{
return(true);
}
}
return(false);
}
/// <summary>
/// 判断点是否在复合多边形内
/// </summary>
/// <param name="point"></param>
/// <param name="multiPolygon"></param>
/// <returns></returns>
public static bool IsPointInMultiPolygon(WEPoint point, WEMultiPolygon multiPolygon)
{
WERectangle box = multiPolygon.MBR;
if (!IsPointInBox(point, box))
{
return(false);
}
int sPolygonCount = multiPolygon.Polygons.Count();
int sIntersectionCount = 0; //射线与边的交点数
for (int j = 0; j < sPolygonCount; j++) //遍历每个简单多边形求射线交点个数
{
WEPolygon thisPolygon = (WEPolygon)multiPolygon.GetPolygon(j);
if (thisPolygon.PointCount < 3)
{
continue;
}
int sPointCount = thisPolygon.PointCount;
WEPoint startPoint, endPoint; //线段起点、终点
for (int i = 0; i < sPointCount - 1; i++)
{
startPoint = thisPolygon.Points[i];
endPoint = thisPolygon.Points[i + 1];
if (IsRayIntersectsSegment(point, startPoint, endPoint))
{
sIntersectionCount++;
}
}
startPoint = thisPolygon.Points[sPointCount - 1];
endPoint = thisPolygon.Points[0];
if (IsRayIntersectsSegment(point, startPoint, endPoint)) //最后一条边
{
sIntersectionCount++;
}
}
if (sIntersectionCount % 2 == 1) //奇数个交点
{
return(true);
}
return(false);
}