using RichCreator.Utility.Structs;
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace RichCreator.Utility.Utilitys
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{
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/// <summary>
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/// 几何体之间的关系类型
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/// </summary>
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public enum Intersection
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{
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None,//没关系
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Tangent,//切线，正切
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Intersection,//相交，交叉
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Containment//包含
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}
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/// <summary>
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/// 与几何相关的辅助类
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/// </summary>
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public static class GeometryHelper
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{
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/// <summary>
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/// 获取点到点的距离
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/// </summary>
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/// <param name="a"></param>
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/// <param name="b"></param>
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/// <returns></returns>
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public static double GetPointDistance(ZTPoint a, ZTPoint b)
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{
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return Math.Sqrt((a.X - b.X) * (a.X - b.X) + (a.Y - b.Y) * (a.Y - b.Y));
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}
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/// <summary>
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/// 获取点到直线的距离
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/// </summary>
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/// <param name="line"></param>
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/// <param name="point"></param>
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/// <returns></returns>
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public static double GetNearestDistance(ZTLinePoint line, ZTPoint point)
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{
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double a, b, c;
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a = GetPointDistance(line.P2, point);
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if (a <= 0.00001)
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{
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return 0.0f;
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}
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b = GetPointDistance(line.P1, point);
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if (b <= 0.00001)
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{
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return 0.0f;
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}
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c = GetPointDistance(line.P1, line.P2);
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if (c <= 0.00001)
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{
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//如果PA和PB坐标相同，则退出函数，并返回距离
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return a;
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}
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if (a * a >= b * b + c * c)
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{
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return b; //如果是钝角返回b
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}
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if (b * b >= a * a + c * c)
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{
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return a; //如果是钝角返回a
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}
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double l = (a + b + c) / 2; //周长的一半
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double s = Math.Sqrt(Math.Abs(l * (l - a) * (l - b) * (l - c))); //海伦公式求面积，也可以用矢量求
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return 2 * s / c;
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}
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/// <summary>
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/// 判断线段与多边形的关系
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/// </summary>
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/// <param name="line"></param>
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/// <param name="polygon"></param>
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/// <returns></returns>
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public static Intersection IntersectionOf(ZTLinePoint line, ZTPolygon polygon)
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{
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if (polygon.Length == 0)
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{
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return Intersection.None;
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}
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if (polygon.Length == 1)
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{
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return IntersectionOf(polygon[0], line);
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}
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bool tangent = false;
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for (int index = 0; index < polygon.Length; index++)
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{
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int index2 = (index + 1) % polygon.Length;
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Intersection intersection = IntersectionOf(line, new ZTLinePoint(polygon[index], polygon[index2]));
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if (intersection == Intersection.Intersection)
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{
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return intersection;
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}
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if (intersection == Intersection.Tangent)
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{
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tangent = true;
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}
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}
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return tangent ? Intersection.Tangent : IntersectionOf(line.P1, polygon);
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}
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/// <summary>
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/// 判断点与多边形的关系
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/// </summary>
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/// <param name="point"></param>
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/// <param name="polygon"></param>
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/// <returns></returns>
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public static Intersection IntersectionOf(ZTPoint point, ZTPolygon polygon)
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{
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switch (polygon.Length)
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{
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case 0:
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return Intersection.None;
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case 1:
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if (polygon[0].X == point.X && polygon[0].Y == point.Y)
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{
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return Intersection.Tangent;
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}
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else
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{
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return Intersection.None;
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}
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case 2:
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return IntersectionOf(point, new ZTLinePoint(polygon[0], polygon[1]));
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}
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int counter = 0;
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int i;
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ZTPoint p1;
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int n = polygon.Length;
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p1 = polygon[0];
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if (point == p1)
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{
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return Intersection.Tangent;
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}
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for (i = 1; i <= n; i++)
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{
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ZTPoint p2 = polygon[i % n];
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if (point == p2)
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{
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return Intersection.Tangent;
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}
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if (point.Y > Math.Min(p1.Y, p2.Y))
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{
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if (point.Y <= Math.Max(p1.Y, p2.Y))
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{
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if (point.X <= Math.Max(p1.X, p2.X))
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{
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if (p1.Y != p2.Y)
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{
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double xinters = (point.Y - p1.Y) * (p2.X - p1.X) / (p2.Y - p1.Y) + p1.X;
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if (p1.X == p2.X || point.X <= xinters)
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counter++;
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}
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}
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}
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}
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p1 = p2;
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}
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return (counter % 2 == 1) ? Intersection.Containment : Intersection.None;
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}
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/// <summary>
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/// 判断点与直线的关系
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/// </summary>
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/// <param name="point"></param>
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/// <param name="line"></param>
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/// <returns></returns>
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public static Intersection IntersectionOf(ZTPoint point, ZTLinePoint line)
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{
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float bottomY = Math.Min(line.Y1, line.Y2);
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float topY = Math.Max(line.Y1, line.Y2);
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bool heightIsRight = point.Y >= bottomY &&
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point.Y <= topY;
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//Vertical line, slope is divideByZero error!
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if (line.X1 == line.X2)
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{
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if (point.X == line.X1 && heightIsRight)
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{
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return Intersection.Tangent;
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}
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else
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{
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return Intersection.None;
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}
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}
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float slope = (line.X2 - line.X1) / (line.Y2 - line.Y1);
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bool onLine = (line.Y1 - point.Y) == (slope * (line.X1 - point.X));
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if (onLine && heightIsRight)
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{
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return Intersection.Tangent;
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}
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else
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{
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return Intersection.None;
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}
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}
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/// <summary>
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/// 判断直线与直线的关系
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/// </summary>
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/// <param name="line1"></param>
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/// <param name="line2"></param>
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/// <returns></returns>
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public static Intersection IntersectionOf(ZTLinePoint line1, ZTLinePoint line2)
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{
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// Fail if either line segment is zero-length.
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if (line1.X1 == line1.X2 && line1.Y1 == line1.Y2 || line2.X1 == line2.X2 && line2.Y1 == line2.Y2)
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return Intersection.None;
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if (line1.X1 == line2.X1 && line1.Y1 == line2.Y1 || line1.X2 == line2.X1 && line1.Y2 == line2.Y1)
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return Intersection.Intersection;
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if (line1.X1 == line2.X2 && line1.Y1 == line2.Y2 || line1.X2 == line2.X2 && line1.Y2 == line2.Y2)
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return Intersection.Intersection;
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// (1) Translate the system so that point A is on the origin.
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line1.X2 -= line1.X1; line1.Y2 -= line1.Y1;
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line2.X1 -= line1.X1; line2.Y1 -= line1.Y1;
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line2.X2 -= line1.X1; line2.Y2 -= line1.Y1;
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// Discover the length of segment A-B.
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double distAB = Math.Sqrt(line1.X2 * line1.X2 + line1.Y2 * line1.Y2);
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// (2) Rotate the system so that point B is on the positive X axis.
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double theCos = line1.X2 / distAB;
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double theSin = line1.Y2 / distAB;
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double newX = line2.X1 * theCos + line2.Y1 * theSin;
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line2.Y1 = (Int32)(line2.Y1 * theCos - line2.X1 * theSin); line2.X1 = (Int32)newX;
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newX = line2.X2 * theCos + line2.Y2 * theSin;
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line2.Y2 = (Int32)(line2.Y2 * theCos - line2.X2 * theSin); line2.X2 = (Int32)newX;
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// Fail if segment C-D doesn't cross line A-B.
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if (line2.Y1 < 0 && line2.Y2 < 0 || line2.Y1 >= 0 && line2.Y2 >= 0)
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return Intersection.None;
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// (3) Discover the position of the intersection point along line A-B.
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double posAB = line2.X2 + (line2.X1 - line2.X2) * line2.Y2 / (line2.Y2 - line2.Y1);
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// Fail if segment C-D crosses line A-B outside of segment A-B.
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if (posAB < 0 || posAB > distAB)
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return Intersection.None;
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// (4) Apply the discovered position to line A-B in the original coordinate system.
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return Intersection.Intersection;
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}
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}
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}
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