namespace Yw.Curve
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{
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public static class CurvePoint_Extensions
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{
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/// <summary>
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/// 计算总长度
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/// </summary>
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public static double CalcuTotalLength(this List<CurvePoint> ptList)
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{
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if (ptList == null || ptList.Count < 1)
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{
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return default;
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}
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double length = 0;
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for (int i = 1; i < ptList.Count; i++)
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{
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length += ptList[i].Distance(ptList[i - 1]);
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}
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return length;
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}
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/// <summary>
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/// 获取Y最小的点
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/// </summary>
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public static CurvePoint GetPointByMinY(this List<CurvePoint> ptList)
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{
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if (ptList == null || ptList.Count < 1)
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{
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return default;
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}
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return ptList.OrderBy(x => x.Y).FirstOrDefault();
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}
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/// <summary>
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/// 获取Y最大的点
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/// </summary>
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public static CurvePoint GetPointByMaxY(this List<CurvePoint> ptList)
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{
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if (ptList == null || !ptList.Any())
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{
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return default;
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}
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return ptList.OrderBy(x => x.Y).LastOrDefault();
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}
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/// <summary>
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/// 获取Y最小的点索引
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/// </summary>
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public static int GetPointIndexByMinY(this List<CurvePoint> ptList)
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{
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var pt = GetPointByMinY(ptList);
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return ptList.IndexOf(pt);
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}
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/// <summary>
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/// 获取Y最大的点索引
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/// </summary>
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public static int GetPointIndexByMaxY(this List<CurvePoint> ptList)
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{
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var pt = GetPointByMaxY(ptList);
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return ptList.IndexOf(pt);
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}
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/// <summary>
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/// 根据X 获取点索引
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/// </summary>
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public static int GetPointIndexByX(this List<CurvePoint> ptList, double x)
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{
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if (ptList == null || !ptList.Any())
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{
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return -1;
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}
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int index = 0;
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foreach (var pt in ptList)
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{
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if (Math.Abs(pt.X - x) < 0.0001)
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{
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return index;
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}
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index++;
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}
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return -1;
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}
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/// <summary>
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/// 获取X方向距离最小的点
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/// </summary>
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public static CurvePoint GetClosestPointByX(this List<CurvePoint> ptList, double x)
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{
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if (ptList == null || ptList.Count < 1)
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{
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return default;
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}
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var pt = ptList.OrderBy(t => Math.Abs(t.X - x)).FirstOrDefault();
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return pt;
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}
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/// <summary>
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/// 获取X方向距离最小的点索引
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/// </summary>
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public static int GetClosestPointIndexByX(this List<CurvePoint> ptList, double x)
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{
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var pt = GetClosestPointByX(ptList, x);
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return ptList.IndexOf(pt);
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}
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/// <summary>
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/// 获得X值的坐标位置,可能有多个点(是线形插值,不是曲线上的点)
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/// </summary>
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public static List<double> GetInterPointY(this List<CurvePoint> ptList, double x)
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{
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if (ptList == null || ptList.Count < 1)
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{
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return default;
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}
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var list = ptList.ToList();
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var equalPoints = new List<double>();
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int num = ptList.Count;
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for (int i = 0; i < num - 1; i++)//少一个点
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{
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if ((x >= list[i].X && x <= list[i + 1].X) || (x <= list[i].X && x >= list[i + 1].X))
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{//直线插值
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double y;
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if (Math.Abs(list[i].X - list[i + 1].X) < 0.01)
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y = (list[i].Y + list[i + 1].Y) * 0.5;
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else
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y = list[i].Y + (list[i + 1].Y - list[i].Y) * (x - list[i].X) / (list[i + 1].X - list[i].X);
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equalPoints.Add(y);
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}
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}
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return equalPoints;
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}
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/// <summary>
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/// ptList 是一个多边形,判断点是否在多边形里
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/// 原理是 通过p做一个+X方向的射线, 偶数个交点 就是在外部,奇数个就是在内部
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/// </summary>
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public static bool IsInPolygon(this IEnumerable<CurvePoint> ptList, CurvePoint p, bool isClosed = true)
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{
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if (ptList == null || ptList.Count() < 1)
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return default;
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var list = ptList.ToList();
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int crossNum = 0;
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for (int i = 0; i < list.Count() - 1; i++)
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{
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if (p.IsIntersectLineLeft(list[i], list[i + 1]))
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{
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crossNum++;
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}
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}
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if (isClosed)
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{
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if (p.IsIntersectLineLeft(list[list.Count - 1], list[0]))
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{
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crossNum++;
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}
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}
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if ((crossNum % 2) == 0)
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return false;
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else
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return true;
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}
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}
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}
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