判断点是否在多边形的范围内
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(point2[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);}}原文链接:http://peizhiinfo.iteye.com/blog/1237481