JavaFX - Rotation Transformation

In rotation, we rotate the object at a particular angle θ (theta) from its origin. From the following figure, we can see that the point P(X, Y) is located at angle φ from the horizontal X coordinate with distance r from the origin.

Rotation

Rotation Transformation in JavaFX

Rotation Transformation is applied on JavaFX nodes using the Rotate class of the javafx.scene.transform package. In this transformation, an affine object is rotated at a specified angle with certain coordinates set as anchor point.

Example 1

Following is the program which demonstrates the rotation transformation in JavaFX. In here, we are creating 2 rectangular nodes at the same location, with the same dimensions but with different colors (Burlywood and Blue). We are also applying rotation transformation on the rectangle with Burlywood color.

Save this code in a file with the name RotationExample.java.

import javafx.application.Application; 
import javafx.scene.Group; 
import javafx.scene.Scene; 
import javafx.scene.paint.Color; 
import javafx.scene.shape.Rectangle; 
import javafx.scene.transform.Rotate; 
import javafx.stage.Stage; 
         
public class RotationExample extends Application { 
   @Override 
   public void start(Stage stage) { 
      //Drawing Rectangle1 
      Rectangle rectangle1 = new Rectangle(150, 75, 200, 150); 
      rectangle1.setFill(Color.BLUE); 
      rectangle1.setStroke(Color.BLACK);  
      
      //Drawing Rectangle2 
      Rectangle rectangle2 = new Rectangle(150, 75, 200, 150); 
      
      //Setting the color of the rectangle 
      rectangle2.setFill(Color.BURLYWOOD); 
      
      //Setting the stroke color of the rectangle 
      rectangle2.setStroke(Color.BLACK); 
       
      //creating the rotation transformation 
      Rotate rotate = new Rotate(); 
      
      //Setting the angle for the rotation 
      rotate.setAngle(20); 
      
      //Setting pivot points for the rotation 
      rotate.setPivotX(150); 
      rotate.setPivotY(225); 
        
      //Adding the transformation to rectangle2 
      rectangle2.getTransforms().addAll(rotate); 
        
      //Creating a Group object
      Group root = new Group(rectangle1, rectangle2); 
         
      //Creating a scene object 
      Scene scene = new Scene(root, 600, 300);  
      
      //Setting title to the Stage 
      stage.setTitle("Rotation transformation example"); 
         
      //Adding scene to the stage 
      stage.setScene(scene); 
         
      //Displaying the contents of the stage 
      stage.show(); 
   } 
   public static void main(String args[]){ 
      launch(args); 
   } 
}

Compile and execute the saved java file from the command prompt using the following commands.

javac --module-path %PATH_TO_FX% --add-modules javafx.controls RotationExample.java 
java --module-path %PATH_TO_FX% --add-modules javafx.controls RotationExample

Output

On executing, the above program generates a javaFx window as shown below.

Rotation Transformation

Example 2

In this example, we are trying to rotate a 3D object, say box. Here, let us create two boxes: one representing its original position, and the other displaying the transformed position.

Save this code in a file with the name RotationExample3D.java.

import javafx.application.Application; 
import javafx.scene.Group; 
import javafx.scene.Scene; 
import javafx.scene.shape.Box;
import javafx.scene.transform.Rotate; 
import javafx.scene.transform.Translate; 
import javafx.stage.Stage; 
         
public class RotationExample3D extends Application { 
   @Override 
   public void start(Stage stage) { 
      //Drawing a Box 
      Box box1 = new Box();
      Box box2 = new Box();	  
      
      //Setting the properties of the Box 
      box1.setWidth(150.0); 
      box1.setHeight(150.0);   
      box1.setDepth(150.0);

      //Setting the properties of the Box 
      box2.setWidth(150.0); 
      box2.setHeight(150.0);   
      box2.setDepth(150.0);	  
       
      //Creating the translation transformation 
      Translate translate = new Translate();       
      translate.setX(200); 
      translate.setY(150); 
      translate.setZ(25);  
       
      Rotate rxBox = new Rotate(0, 0, 0, 0, Rotate.X_AXIS); 
      Rotate ryBox = new Rotate(0, 0, 0, 0, Rotate.Y_AXIS); 
      Rotate rzBox = new Rotate(0, 0, 0, 0, Rotate.Z_AXIS); 
      rxBox.setAngle(30); 
      ryBox.setAngle(50); 
      rzBox.setAngle(30); 
      box2.getTransforms().addAll(translate,rxBox, ryBox, rzBox); 
        
      //Creating a Group object  
      Group root = new Group(box1, box2); 
         
      //Creating a scene object 
      Scene scene = new Scene(root, 400, 300);  
      
      //Setting title to the Stage 
      stage.setTitle("Transformation of a Box"); 
         
      //Adding scene to the stage 
      stage.setScene(scene); 
         
      //Displaying the contents of the stage 
      stage.show(); 
   }      
   public static void main(String args[]){ 
      launch(args); 
   } 
}

Compile and execute the saved java file from the command prompt using the following commands.

javac --module-path %PATH_TO_FX% --add-modules javafx.controls RotationExample3D.java 
java --module-path %PATH_TO_FX% --add-modules javafx.controls RotationExample3D

Output

On executing, the above program generates a JavaFX window as shown below. We can observe that the original position of the box is not completely within the application; hence, applying the transformation becomes necessary.

Rotation Transformation
Advertisements