Javafx 简明教程

JavaFX - PerspectiveTransform

通常，2D 对象只能在二维平面中绘制，且仅用两个维度进行测量。但是，借助 JavaFX 应用程序，你可以对 2D 对象提供 3D 错觉。这种效果被称为透视变换效果。

Usually, 2D objects are objects that can only be drawn on two-dimensional planes and are measured with two dimensions only. However, using the JavaFX application you can provide a 3D illusion of a 2D object. This effect is known as a Perspective Transform Effect.

透视变换效果将在 Z 轴方向创建透视，使得物体看起来仿佛可以在 XYZ 平面中进行测量，而实际上它只是在 XY 平面中测量。这种效果提供了非仿射变换，其中源对象中线的直线性在输出对象中得到保留。但是，与仿射变换不同，平行性会丢失。

The Perspective Transform effect will create a perspective in the direction of the Z-axis such that the object looks like it can be measured on the XYZ-plane while it actually is just measured on the XY-plane. This effect provides non-affine transformation where the straightness of lines in the source object is preserved in the output object. However, the parallelism is lost; unlike the affine transformation.

你可以使用 javafx.scene.effect 包中的 PerspectiveTransform 类将这种效果应用于 JavaFX 节点。此类具有以下属性：

You can apply this effect on a JavaFX node using the PerspectiveTransform class in the javafx.scene.effect package. This class has the following properties −

  1. input − The input for this Effect.

  2. llx − The x coordinate of the output location onto which the lower left corner of the source is mapped.

  3. lly − The y coordinate of the output location onto which the lower left corner of the source is mapped.

  4. lrx − The x coordinate of the output location onto which the lower right corner of the source is mapped.

  5. lry − The y coordinate of the output location onto which the lower right corner of the source is mapped.

  6. ulx − The x coordinate of the output location onto which the upper left corner of the source is mapped.

  7. uly − The y coordinate of the output location onto which the upper left corner of the source is mapped.

  8. urx − The x coordinate of the output location onto which the upper right corner of the source is mapped.

  9. ury − The y coordinate of the output location onto which the upper right corner of the source is mapped.

Example

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.shape.Rectangle;
import javafx.scene.effect.Effect;
import javafx.scene.effect.PerspectiveTransform;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.scene.text.Text;

public class PerspectiveTransformExample extends Application {
   @Override
   public void start(Stage stage) {
      PerspectiveTransform prst = new PerspectiveTransform();
      prst.setUlx(10.0);
      prst.setUly(10.0);
      prst.setUrx(310.0);
      prst.setUry(40.0);
      prst.setLrx(310.0);
      prst.setLry(60.0);
      prst.setLlx(10.0);
      prst.setLly(90.0);

      Group g = new Group();
      g.setEffect(prst);
      g.setCache(true);

      Rectangle rect = new Rectangle();
      rect.setX(10.0);
      rect.setY(10.0);
      rect.setWidth(280.0);
      rect.setHeight(80.0);
      rect.setFill(Color.BLUE);

      Text text = new Text();
      text.setX(20.0);
      text.setY(65.0);
      text.setText("JavaFX App");
      text.setFill(Color.WHITE);
      text.setFont(Font.font(null, FontWeight.BOLD, 36));

      g.getChildren().addAll(rect, text);

	  //Creating a Group object
      Group root = new Group(g);

      //Creating a scene object
      Scene scene = new Scene(root, 600, 300);

      //Setting title to the Stage
      stage.setTitle("Perspective Transform Effect");

      //Adding scene to the stage
      stage.setScene(scene);

      //Displaying the contents of the stage
      stage.show();
   }
   public static void main(String args[]){
      launch(args);
   }
}

使用以下命令，从命令提示符编译并执行已保存的 java 文件。

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 PerspectiveTransformExample.java
java --module-path %PATH_TO_FX% --add-modules javafx.controls PerspectiveTransformExample

Output

执行后，上述程序会生成如下所示的 JavaFX 窗口。

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

perspectivetransform