Java PathIterator順時針或逆時針？

Question

Java PathIterator是否以順時針或逆時針順序爲您提供多邊形的點？

Answer 1

它按點在多邊形中定義的順序「走」。考慮下面的代碼示例我剛颳起：

c:\files\j>java ShapeTest 
Walking clockwise 
Currently at: 2.0 5.0 
Currently at: 4.0 4.0 
Currently at: 4.0 1.0 
Currently at: 0.0 1.0 
Currently at: 0.0 3.0 
Walking counter-clockwise 
Currently at: 0.0 3.0 
Currently at: 0.0 1.0 
Currently at: 4.0 1.0 
Currently at: 4.0 4.0 
Currently at: 2.0 5.0 

由

import java.awt.Polygon; 
import java.awt.geom.PathIterator; 
class ShapeTest { 
    /** 
    * Use points to make a pentagon 
       . 2,5 
     0,3 . . 4,3 
     0,1 . . 4,1 

    */ 
    public static void main(String...args) { 
     // from the top clockwise 
     int[] xClock = new int[] { 2,4,4,0,0 }; 
     int[] yClock = new int[] { 5,4,1,1,3 }; 

     // the reverse order from the clockwise way 
     int[] xCounter = new int[] { 0,0,4,4,2 }; 
     int[] yCounter = new int[] { 3,1,1,4,5 }; 

     Polygon clock = new Polygon(xClock, yClock, 5); 
     Polygon counter = new Polygon(xCounter, yCounter, 5); 

     int index = 0; 

     System.out.println("Walking clockwise"); 
     PathIterator clockIter = clock.getPathIterator(null); 

     while(!clockIter.isDone() && index < clock.npoints) { 
      float[] coords = new float[6]; 
      clockIter.currentSegment(coords); 
      System.out.println("Currently at: " + coords[0] + " " + coords[1]); 
      clockIter.next(); 
      index++; 
     } 

     index = 0; 

     System.out.println("Walking counter-clockwise"); 
     PathIterator counterIter = counter.getPathIterator(null); 
     while(!counterIter.isDone() && index < counter.npoints) { 
      float[] coords = new float[6]; 
      counterIter.currentSegment(coords); 
      System.out.println("Currently at: " + coords[0] + " " + coords[1]); 
      counterIter.next(); 
      index++; 
     } 

    } 
}