JavaFX 類 Point3D用法及代碼示例

Point3D類是JavaFX的一部分。此類定義3D空間中的3維點。 Point3D類通過其x，y，z坐標表示3D點。

該類的構造函數是：

• Point3D(double x, double y, double z)：使用指定的坐標創建Point3D對象。

常用方法：

方法	說明
distance(double x, double y, double z)	計算此點與指定點之間的距離
distance(Point3D p)	計算此點與指定Point3D對象之間的距離
equals(java.lang.Object o)	返回該點的哈希碼值。
getX()	返回x坐標
getY()	返回y坐標
getZ()	返回z坐標
hashCode()	返回此Point3D對象的哈希碼。

下麵的程序將說明Point3D類的用法：

1. Java程序創建一個Point3D對象並顯示其坐標並找到其與原點的距離：在此程序中，我們通過傳遞其x，y，z坐標作為參數來創建一個名為point3d_1的Point3D對象。我們使用getX()，getY()，getZ()函數獲取x，y，z參數並顯示它。我們還計算點到原點的距離並顯示出來。

   // Java program to create a point 3D  
   // object and display its coordinates 
   // and find its distance from origin 
   import javafx.geometry.Point3D; 
     
   public class Point3D_1 { 
     
       // Main Method 
       public static void main(String args[]) 
       { 
     
           // Create a point3D object 
           Point3D point3d_1 = new Point3D(20.0f, 50.0f, 70.0f); 
     
           double x, y, z; 
     
           // get the coordinates of the point 
           x = point3d_1.getX(); 
           y = point3d_1.getY(); 
           z = point3d_1.getZ(); 
     
           // display the coordinates of the point 
           System.out.println("x coordinate = " + x  
                               + ", y coordinate = " 
                               + y + ", z coordinate = " + z); 
     
           // print its distance from origin 
           System.out.println("Distance From Origin = " 
                        + point3d_1.distance(0, 0, 0)); 
       } 
   }

   輸出：

   x coordinate = 20.0, y coordinate = 50.0, z coordinate = 70.0
   Distance From Origin = 88.31760866327846
   

2. Java程序創建3個Point3D對象並顯示其坐標和距原點的距離，並檢查3個點中的哪個點相似以及兩個點之間的距離：在此程序中，我們通過傳遞其x，y，z坐標作為參數來創建3個Point3D對象，分別命名為point3d_1，point3d_2，point3d_3。我們使用getX()，getY()，getZ()函數獲取x，y，z參數並顯示它。我們還計算了該點到原點的距離，並針對三個點中的每一個都顯示了該距離。我們還使用equals()函數顯示兩個點是否相等，並使用距離函數顯示兩個點之間的距離。

   // Java program to create 3 Point3D objects and  
   // display their coordinates and distance from  
   // origin and check which of the 3 points are  
   // similar and their distances between two points 
   import javafx.geometry.Point3D; 
     
   public class Point3D_2 { 
     
       // Main Method 
       public static void main(String args[]) 
       { 
     
           // create three point3D objects 
           Point3D point3d_1 = new Point3D(20.0f, 50.0f, 70.0f); 
           Point3D point3d_2 = new Point3D(20.0f, 50.0f, 70.0f); 
           Point3D point3d_3 = new Point3D(200.0f, 20.0f, 90.0f); 
     
           // display the coordinates of the 3 points 
           display(point3d_1); 
           display(point3d_2); 
           display(point3d_3); 
     
           // check whether any point is equal to other or not 
           System.out.println("Point 1 equals point 2 = " 
                          + point3d_1.equals(point3d_2)); 
     
           System.out.println("Point 2 equals point 3 = " 
                          + point3d_2.equals(point3d_3)); 
     
           System.out.println("Point 3 equals point 1 = " 
                           + point3d_3.equals(point3d_1)); 
     
           // distance between two points 
           System.out.println("Distane between point 1 and point 2 = " 
                                     + point3d_1.distance(point3d_2)); 
     
           System.out.println("Distane between point 2 and point 3 = " 
                                      + point3d_2.distance(point3d_3)); 
     
           System.out.println("Distane between point 3 and point 1 = " 
                                     + point3d_3.distance(point3d_1)); 
       } 
     
       // Display Method 
       public static void display(Point3D point3d) 
       { 
     
           double x, y, z; 
     
           // get the coordinates of the point 
           x = point3d.getX(); 
           y = point3d.getY(); 
           z = point3d.getZ(); 
     
           // display the coordinates of the point 
           System.out.println("x coordinate = " + x  
                              + ", y coordinate = " 
                              + y + ", z coordinate = " + z); 
     
           // print its distance from origin 
           System.out.println("Distance From Origin = " +  
                               point3d.distance(0, 0, 0)); 
       } 
   }

   輸出：

   x coordinate = 20.0, y coordinate = 50.0, z coordinate = 70.0
   Distance From Origin = 88.31760866327846
   x coordinate = 20.0, y coordinate = 50.0, z coordinate = 70.0
   Distance From Origin = 88.31760866327846
   x coordinate = 200.0, y coordinate = 20.0, z coordinate = 90.0
   Distance From Origin = 220.22715545545242
   Point 1 equals point 2 = true
   Point 2 equals point 3 = false
   Point 3 equals point 1 = false
   Distane between point 1 and point 2 = 0.0
   Distane between point 2 and point 3 = 183.5755975068582
   Distane between point 3 and point 1 = 183.5755975068582
   

注意：以上程序可能無法在在線IDE中運行。請使用離線編譯器。

參考：https://docs.oracle.com/javafx/2/api/javafx/geometry/Point3D.html