判断点是否在多边形的范围内
程序员文章站
2022-04-01 08:53:55
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public class GeometryUtils { public final static double EPSILON=0.00001; public static double getEpsilon(double maxx, double maxy,double minx, double miny, double epsilon){ if((maxy-miny+maxx-minx)==0)return epsilon; return Math.abs(epsilon/(maxy-miny+maxx-minx)); } // / <summary> // / <para>判断点是否在多边形的范围内</para> // / <para>返回值:值为1表示点在多边形范围内;</para> // / <para>值为0表示点在多边形边上;</para> // / <para>值为-1表示点不在多边形范围内。</para> // / </summary> // / <param name="point">点坐标,长度为2</param> // / <param name="polyline">多边形节点坐标,长度为2*n,其中n应大于或等于3,即至少为三角形</param> // / <returns> // / <para>返回值:值为1表示点在多边形范围内;</para> // / <para>值为0表示点在多边形边上;</para> // / <para>值为-1表示点不在多边形范围内。</para> // / </returns> public static int polygonIsContainPoint(double[] point, double[] polyline) { int result = -1, count = 0, pointcount = 0, tempI; double maxx = 0, minx = 0, maxy = 0, miny = 0; if (polyline != null) { int i; pointcount = polyline.length / 2; maxx = minx = polyline[0]; maxy = miny = polyline[1]; for (i = 0; i < pointcount; i++) { tempI = i + i; if (maxx < polyline[tempI]) maxx = polyline[tempI]; if (minx > polyline[tempI]) minx = polyline[tempI]; if (maxy < polyline[tempI + 1]) maxy = polyline[tempI + 1]; if (miny > polyline[tempI + 1]) miny = polyline[tempI + 1]; } } double epsilon = getEpsilon(maxx, maxy, minx, miny, EPSILON); if (point != null) { // 首先判断是否在面的外框范围内 if (point[0] < minx || point[0] > maxx || point[1] < miny || point[1] > maxy) { System.out.println("直接out"); return result; } else { int i, j; j = pointcount - 1; double[] point1, point2; double tempValue; for (i = 0; i < pointcount; i++) { point1 = new double[2]; point2 = new double[2]; tempI = i + i; point1[0] = polyline[tempI]; point1[1] = polyline[tempI + 1]; tempI = j + j; point2[0] = polyline[tempI]; point2[1] = polyline[tempI + 1]; if ((lt(point1[0] , point[0],epsilon) && (eq(point2[0],point[0],epsilon) || gt(point2[0] , point[0],epsilon) ) ) || (lt(point2[0] , point[0],epsilon) && (eq(point1[0],point[0],epsilon)) || gt(point1[0], point[0],epsilon) )) { tempValue = point1[1] + (point[0] - point1[0]) / (point2[0] - point1[0]) * (point2[1] - point1[1]); if (tempValue < point[1]) { count++; } else if (eq(tempValue ,point[1],epsilon)) { count = -1; break; } } j = i; } } } if (count == -1) { result = 0;// 点在线段上 } else { tempI = count % 2; if (tempI == 0)// 为偶数 { result = -1; } else { result = 1; } } return result; } public static boolean eq(double a,double b, double epsilon){ return Math.abs(a-b)<epsilon; } public static boolean gt(double a,double b, double epsilon){ return a-b>=epsilon; } public static boolean lt(double a,double b, double epsilon){ return b-a>=epsilon; } public static void main(String[] args){ int result = polygonIsContainPoint(new double[]{106.63,35.85}, new double[]{106.61502,35.84901, 106.61605,35.85133, 106.62112,35.85416, 106.62635,35.85305, 106.63725,35.85219, 106.64867,35.84953, 106.65021,35.84627, 106.65202,35.84052, 106.64472,35.84352, 106.63991,35.84781, 106.63399,35.84798, 106.62807,35.84549, 106.62258,35.84704, 106.61674,35.84841}); System.out.println(result); result = polygonIsContainPoint(new double[]{106.61502,35.84901}, new double[]{106.61502,35.84901, 106.61605,35.85133, 106.62112,35.85416, 106.62635,35.85305, 106.63725,35.85219, 106.64867,35.84953, 106.65021,35.84627, 106.65202,35.84052, 106.64472,35.84352, 106.63991,35.84781, 106.63399,35.84798, 106.62807,35.84549, 106.62258,35.84704, 106.61674,35.84841}); System.out.println(result); result = polygonIsContainPoint(new double[]{10,10}, new double[]{106.61502,35.84901, 106.61605,35.85133, 106.62112,35.85416, 106.62635,35.85305, 106.63725,35.85219, 106.64867,35.84953, 106.65021,35.84627, 106.65202,35.84052, 106.64472,35.84352, 106.63991,35.84781, 106.63399,35.84798, 106.62807,35.84549, 106.62258,35.84704, 106.61674,35.84841}); System.out.println(result); } }
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