射线法判断一个点是否在一个多边形内
http://hi..com/xiaoheng199110/item/a63ae6fbfab88e1efe358237
Ⅱ JAVA中正多边形的问题已知一个点到另外N个点的距离，用JAVA求出这N个点是否为正多边形，若是求边长
你好，这个题确实描述的不准确。 你可以建立一个数学模型，求解，按照求解过程去编程。
Ⅲ 判断点是否多边形内部java
//方法一
(Point2D.Doublepoint,List<Point2D.Double>polygon){
java.awt.geom.GeneralPathp=newjava.awt.geom.GeneralPath();
Point2D.Doublefirst=polygon.get(0);
p.moveTo(first.x,first.y);
for(Point2D.Doubled:polygon){
p.lineTo(d.x,d.y);
}
p.lineTo(first.x,first.y);
p.closePath();
returnp.contains(point);
}
//方法二
(Point2D.Doublepoint,List<Point2D.Double>polygon){
java.awt.Polygonp=newPolygon();
//java.awt.geom.GeneralPath
finalintTIMES=1000;
for(Point2D.Doubled:polygon){
intx=(int)d.x*TIMES;
inty=(int)d.y*TIMES;
p.addPoint(x,y);
}
intx=(int)point.x*TIMES;
inty=(int)point.y*TIMES;
returnp.contains(x,y);
}
Ⅳ Java 判断 一个点是不是在一个多边形围起来
MobilelocationEntity 是手机位置信息类 包含经度纬度
Enclosure 围栏类 每一个对象是形成多边形围栏的一个点 包含经度纬度
[java]view plain
packagecom.snicomsi.util.map;
importjava.awt.geom.Point2D;
importjava.util.ArrayList;
importjava.util.List;
importcom.snicomsi.cgzft.entity.gis.Enclosure;
importcom.snicomsi.cgzft.entity.gis.MobilelocationEntity;
/**
*
*@authorlxg
*
*/
publicclassMapTools{
/**
*判断当前位置是否在围栏内
*@parammobilelocationEntity
*@paramenclosureList
*@return
*/
(,List<Enclosure>enclosureList){
doublep_x=Double.parseDouble(mobilelocationEntity.getLongitude());
doublep_y=Double.parseDouble(mobilelocationEntity.getLatitude());
Point2D.Doublepoint=newPoint2D.Double(p_x,p_y);
List<Point2D.Double>pointList=newArrayList<Point2D.Double>();
for(Enclosureenclosure:enclosureList){
doublepolygonPoint_x=enclosure.getLongitude();
doublepolygonPoint_y=enclosure.getLatitude();
Point2D.DoublepolygonPoint=newPoint2D.Double(polygonPoint_x,polygonPoint_y);
pointList.add(polygonPoint);
}
MapToolstest=newMapTools();
returntest.checkWithJdkGeneralPath(point,pointList);
}
/**
*返回一个点是否在一个多边形区域内
*@parampoint
*@parampolygon
*@return
*/
(Point2D.Doublepoint,List<Point2D.Double>polygon){
java.awt.geom.GeneralPathp=newjava.awt.geom.GeneralPath();
Point2D.Doublefirst=polygon.get(0);
p.moveTo(first.x,first.y);
polygon.remove(0);
for(Point2D.Doubled:polygon){
p.lineTo(d.x,d.y);
}
p.lineTo(first.x,first.y);
p.closePath();
returnp.contains(point);
}
}
[java]view plain
第二种方法
[java]view plain
//方法二
//方法二
(Point2D.Doublepoint,List<Point2D.Double>polygon){
java.awt.Polygonp=newPolygon();
//java.awt.geom.GeneralPath
finalintTIMES=1000;
for(Point2D.Doubled:polygon){
intx=(int)d.x*TIMES;
inty=(int)d.y*TIMES;
p.addPoint(x,y);
}
intx=(int)point.x*TIMES;
inty=(int)point.y*TIMES;
returnp.contains(x,y);
}
Ⅳ 急求！！14号就要用！用JAVA编写：输入N个点的坐标，判断这N个点能否构成一个凸多边形。十分感谢！
/**
* 原理： 凸多边形的定义，以某一边做直线，其他各点必在该直线同一侧
* @author tjx
*
*/
public class Mshape {
/*判定点p 与直线位置，这里忽略了点p在直线l上的情况，你可以适当补充完善*/
private static boolean pointPosition(Line l,Point p){
if(l.isVertical()){
if(p.getX()- l.getC()<0) return true;
else return false;
}else{
if(p.getY()-l.getK()*p.getX()-l.getC()>0)
return true;
else
return false;
}
}
/*根据点数组判定是否是凸多边形*/
public static boolean isCp(Point[] ps){
if(ps.length<3) // 点数大于等于三
return false;
boolean isLeft = false; //某点是否在另外两点组成直线的左边
Line l = null;
for(int i=0;i<ps.length-1;i++){
boolean isFirstTime = true;
label:
for(int j=i+1;j<ps.length;j++){
l = new Line(ps[i],ps[j]);
int times = 0;
for(int k=0;k<ps.length;k++){
if(k==i || k == j)
continue;
if(isFirstTime){ //记录第一点相对直线的位置，是否在其左边
isFirstTime = false;
isLeft = pointPosition(l, ps[k]);
times ++;
}else{
boolean isL = pointPosition(l, ps[k]);
times++;
if(isLeft != isL){ //各点不在直线l的同一边，换线
continue label;
}
if(isLeft == isL && times == ps.length-2 )
return true;
}
}
}
}
return false;
}
public static void main(String[] args){
Point[] ps= new Point[4]; //这个数字可以由main参数来控制
ps[0] = new Point(1,1);
ps[1] = new Point(8,8);
ps[2] = new Point(9,0);
ps[3] = new Point(0,9);
System.out.println( Mshape.isCp(ps));
}
}
class Point{
public Point(){
}
public Point(double x,double y){
this.x = x;
this.y = y;
}
public double getX() {
return x;
}
public void setX(double x) {
this.x = x;
}
public double getY() {
return y;
}
public void setY(double y) {
this.y = y;
}
private double x;
private double y;
}
class Line {
private double k;//斜率
private double c;//常数
private boolean isVertical = false; //是否垂直直线
public Line(){};
public Line(Point p1,Point p2){
if(p1.getY()-p2.getY() != 0){
this.k = (p1.getY()-p2.getY())/(p1.getX()-p2.getX());
this.c = p1.getY()-k*p1.getX();
}else{ //垂直线
this.c = p1.getX();
this.isVertical = true;
}
}
public Line(Double k,Double c){
this.k = k;
this.c = c;
}
public double getK() {
return k;
}
public void setK(double k) {
this.k = k;
}
public double getC() {
return c;
}
public void setC(double c) {
this.c = c;
}
public boolean isVertical() {
return isVertical;
}
public void setVertical(boolean isVertical) {
this.isVertical = isVertical;
}
}
Ⅵ java中如何写一个射线法，判断点是否在多边形内
楼上的方法判断不准。
鉴定完毕。
三角形内点与顶点的连线斜率一定在对应的两直线斜率之间，斜率好计算吧