java判断某个点是否在所画范围内(多边形/圆形)

超、凢脫俗 2022-06-05 03:44 690阅读 0赞

如题：

IsPtInPoly.java

package com.ardo.util.circle;
    
    import java.util.ArrayList;
    import java.util.List;
    
    /** 
     * java判断某个点是否在所画范围内(多边形【isPtInPoly】/圆形【distencePC】) 
     * @param point 检测点 
     * @param pts   多边形的顶点 
     * @return      点在多边形内返回true,否则返回false 
     * @author 		ardo
     */ 
    public class IsPtInPoly {
    	
    	/** 
    	 * 判断点是否在多边形内 
    	 * @param point 检测点 
    	 * @param pts   多边形的顶点 
    	 * @return      点在多边形内返回true,否则返回false 
    	 */  
    	public static boolean isPtInPoly(Point2D point, List<Point2D> pts){  
    	      
    	    int N = pts.size();  
    	    boolean boundOrVertex = true; //如果点位于多边形的顶点或边上，也算做点在多边形内，直接返回true  
    	    int intersectCount = 0;//cross points count of x   
    	    double precision = 2e-10; //浮点类型计算时候与0比较时候的容差  
    	    Point2D p1, p2;//neighbour bound vertices  
    	    Point2D p = point; //当前点  
    	      
    	    p1 = pts.get(0);//left vertex          
    	    for(int i = 1; i <= N; ++i){//check all rays              
    	        if(p.equals(p1)){  
    	            return boundOrVertex;//p is an vertex  
    	        }  
    	          
    	        p2 = pts.get(i % N);//right vertex              
    	        if(p.x < Math.min(p1.x, p2.x) || p.x > Math.max(p1.x, p2.x)){//ray is outside of our interests                  
    	            p1 = p2;   
    	            continue;//next ray left point  
    	        }  
    	          
    	        if(p.x > Math.min(p1.x, p2.x) && p.x < Math.max(p1.x, p2.x)){//ray is crossing over by the algorithm (common part of)  
    	            if(p.y <= Math.max(p1.y, p2.y)){//x is before of ray                      
    	                if(p1.x == p2.x && p.y >= Math.min(p1.y, p2.y)){//overlies on a horizontal ray  
    	                    return boundOrVertex;  
    	                }  
    	                  
    	                if(p1.y == p2.y){//ray is vertical                          
    	                    if(p1.y == p.y){//overlies on a vertical ray  
    	                        return boundOrVertex;  
    	                    }else{//before ray  
    	                        ++intersectCount;  
    	                    }   
    	                }else{//cross point on the left side                          
    	                    double xinters = (p.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x) + p1.y;//cross point of y                          
    	                    if(Math.abs(p.y - xinters) < precision){//overlies on a ray  
    	                        return boundOrVertex;  
    	                    }  
    	                      
    	                    if(p.y < xinters){//before ray  
    	                        ++intersectCount;  
    	                    }   
    	                }  
    	            }  
    	        }else{//special case when ray is crossing through the vertex                  
    	            if(p.x == p2.x && p.y <= p2.y){//p crossing over p2                      
    	                Point2D p3 = pts.get((i+1) % N); //next vertex                      
    	                if(p.x >= Math.min(p1.x, p3.x) && p.x <= Math.max(p1.x, p3.x)){//p.x lies between p1.x & p3.x  
    	                    ++intersectCount;  
    	                }else{  
    	                    intersectCount += 2;  
    	                }  
    	            }  
    	        }              
    	        p1 = p2;//next ray left point  
    	    }  
    	      
    	    if(intersectCount % 2 == 0){//偶数在多边形外  
    	        return false;  
    	    } else { //奇数在多边形内  
    	        return true;  
    	    }  
    	      
    	} 
    	
    	/**
    	 * 判断是否在圆形内
    	 * @param p
    	 * @param c
    	 * @return
    	 */
    	public static String distencePC(Point2D p,Circle c){//判断点与圆心之间的距离和圆半径的关系
            String s ;
            double d2 = Math.hypot( (p.getX() - c.getCC().getX() ), (p.getY() - c.getCC().getY()) );
            System.out.println("d2=="+d2);
            double r = c.getR();
            if(d2 > r){
                  s = "圆外";
            }else if(d2 < r){
                 s = "圆内";
            }else{
                  s = "圆上";
            }
            return s;
    	}
    
    	
    	
    	
    	public static void main(String[] args) {  
    	      
    	    Point2D point = new Point2D(116.404072, 39.916605);  
    	      
    	    // 测试一个点是否在多边形内  
    	    List<Point2D> pts = new ArrayList<Point2D>();  
    	    pts.add(new Point2D(116.395, 39.910));  
    	    pts.add(new Point2D(116.394, 39.914));  
    	    pts.add(new Point2D(116.403, 39.920));  
    	    pts.add(new Point2D(116.402, 39.914));  
    	    pts.add(new Point2D(116.410, 39.913));  
    	      
    	    if(isPtInPoly(point, pts)){  
    	        System.out.println("点在多边形内");  
    	    }else{  
    	        System.out.println("点在多边形外");  
    	    }  
    	    
    	    // 测试一个点是否在圆形内  
    	    Point2D centerPoint = new Point2D(116.404172, 39.916605);  
    	    Circle c = new Circle();
            c.setCC(centerPoint);
            c.setR(0.0056);
            String s = distencePC(point,c);
            System.out.println("点是否在圆内："+s);
    	} 
    	
    }

Circle.java

/**
     * 圆形类
     * @author ardo
     *
     */
    public class Circle {
    	 private double r;
         private Point2D cc;
         
         public void setR(double a){
               r = a;
         }
         public void setCC(Point2D centerOfCir){
               cc = centerOfCir;
         }
         public double getR(){
               return r;
         }
         public Point2D getCC(){
               return cc;
         }
    }

Point2D.java

public class Point2D {
    	
    	public double x;
    	public double y;
    	
    	public Point2D(double x, double y) {
    		super();
    		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;
    	}
    	
    }