Merge pull request #78 from HarryDulaney/chapter-15-solutions

add 24 and 25
HarryDulaney · Nov 25, 2023 · 05a7945 · 05a7945
2 parents 8db4552 + fc175bc
commit 05a7945
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Showing 2 changed files with 137 additions and 11 deletions.
diff --git a/ch_15/Exercise15_24.java b/ch_15/Exercise15_24.java
@@ -3,12 +3,16 @@
 import javafx.animation.PathTransition;
 import javafx.animation.Timeline;
 import javafx.application.Application;
+import javafx.collections.ObservableList;
 import javafx.scene.Scene;
-import javafx.scene.Group;
-import javafx.scene.layout.BorderPane;
+import javafx.scene.layout.Pane;
 import javafx.scene.paint.Color;
 import javafx.scene.shape.Arc;
 import javafx.scene.shape.Circle;
+import javafx.scene.shape.Line;
+import javafx.scene.shape.Polyline;
+import javafx.scene.text.Font;
+import javafx.scene.text.Text;
 import javafx.stage.Stage;
 import javafx.util.Duration;
 
@@ -21,17 +25,16 @@
 public class Exercise15_24 extends Application {
     @Override
     public void start(Stage primaryStage) {
-        Group group = new Group();
+        Pane pane = new Pane();
+
         Circle circle = new Circle(0, 0, 10);
         circle.setFill(Color.ORANGE);
 
         Arc arc = new Arc(125, 100, 80, 40, 210, 125);
         arc.setFill(Color.WHITE);
         arc.setStroke(Color.BLACK);
-
-        group.getChildren().add(arc);
-        group.getChildren().add(circle);
-
+        pane.getChildren().add(arc);
+        pane.getChildren().add(circle);
         PathTransition pt = new PathTransition();
         pt.setDuration(Duration.millis(4000));
         pt.setPath(arc);
@@ -40,13 +43,15 @@ public void start(Stage primaryStage) {
                 PathTransition.OrientationType.ORTHOGONAL_TO_TANGENT);
         pt.setCycleCount(Timeline.INDEFINITE);
         pt.setAutoReverse(true);
-        pt.play(); // Play animation
+        pt.play();
 
-        group.setOnMousePressed(e -> pt.pause());
-        group.setOnMouseReleased(e -> pt.play());
-        Scene scene = new Scene(new BorderPane(group), 250, 200);
+        pane.setOnMousePressed(e -> pt.pause());
+        pane.setOnMouseReleased(e -> pt.play());
+
+        Scene scene = new Scene(pane, 250, 200);
         primaryStage.setTitle(getClass().getName());
         primaryStage.setScene(scene);
         primaryStage.show();
     }
 }
+
diff --git a/ch_15/Exercise15_25.java b/ch_15/Exercise15_25.java
@@ -1,7 +1,18 @@
 package ch_15;
 
+import javafx.animation.PathTransition;
 import javafx.application.Application;
+import javafx.collections.ObservableList;
+import javafx.scene.Scene;
+import javafx.scene.input.MouseButton;
+import javafx.scene.layout.Pane;
+import javafx.scene.shape.Circle;
+import javafx.scene.shape.Line;
+import javafx.scene.shape.Polyline;
+import javafx.scene.text.Font;
+import javafx.scene.text.Text;
 import javafx.stage.Stage;
+import javafx.util.Duration;
 
 /**
  * **15.25 (Animation: ball on curve) Write a program that animates a ball moving along
@@ -10,8 +21,118 @@
  * a click on the left/right mouse button.
  */
 public class Exercise15_25 extends Application {
+    private final double sceneWidth = 600;
+    private final double sceneHeight = 260;
+    private final int fontSize = 16;
+
+    private final double centerX;
+    private final double centerY;
+
+    public Exercise15_25() {
+        centerX = sceneWidth / 2;
+        centerY = sceneHeight / 2;
+    }
+
     @Override
     public void start(Stage primaryStage) throws Exception {
+        Pane pane = new Pane();
+        Polyline xAxis = new Polyline();
+        Polyline yAxis = new Polyline();
+        drawYAxis(pane, yAxis);
+        drawXAxis(pane, xAxis);
+
+        Polyline polyline1 = new Polyline();
+        ObservableList<Double> list = polyline1.getPoints();
+        int startXValue = -170;
+        int endXValue = 170;
+        for (int x = startXValue; x <= endXValue; x++) {
+            list.add(x + centerX);
+            double y = calculateY(x, centerY);
+            list.add(y);
+            if (isYIntersectingXAxis(y, centerY)) {
+                Text text = new Text(x + centerX, centerY / 0.9, getXAxisLabel(x));
+                pane.getChildren().add(text);
+            }
+
+        }
+        Circle point = new Circle(list.get(0), list.get(1), 10);
+        PathTransition path = new PathTransition(Duration.millis(4000), polyline1, point);
+        path.setCycleCount(PathTransition.INDEFINITE);
+        pane.getChildren().addAll(xAxis, yAxis, polyline1, point);
+        pane.setOnMouseClicked(e -> {
+            if (e.getButton() == MouseButton.PRIMARY) {
+                path.play();
+            } else if (e.getButton() == MouseButton.SECONDARY) {
+                path.pause();
+            }
+        });
+        primaryStage.setScene(new Scene(pane, sceneWidth, sceneHeight));
+        primaryStage.setTitle(getClass().getName());
+        primaryStage.show();
+
+    }
+
+    private double calculateY(int x, double centerY) {
+        return centerY - 50 * Math.sin((x / 100.0) * 2 * Math.PI);
+    }
+
+    private boolean isYIntersectingXAxis(double y, double centerY) {
+        return y - centerY < 0.01 && y - centerY > -0.01;
+    }
+
+    private void drawXAxis(Pane pane, Polyline xAxis) {
+        ObservableList<Double> xAxisList = xAxis.getPoints();
+        double limit = sceneWidth * 0.95;
+
+        for (double x = 0; x < limit; x++) {
+            xAxisList.add(x);
+            xAxisList.add(centerY);
+        }
 
+        Line line1 = new Line(limit, centerY, limit - sceneWidth * 0.05, centerY * 0.875);
+        Line line2 = new Line(limit, centerY, limit - sceneWidth * 0.05, centerY / 0.875);
+        Text text = new Text(limit + (sceneWidth * 0.02), centerY, "X");
+        text.setFont(Font.font(fontSize));
+        pane.getChildren().addAll(line1, line2, text);
     }
+
+    private void drawYAxis(Pane pane, Polyline yAxis) {
+
+        ObservableList<Double> yAxisList = yAxis.getPoints();
+        double limit = sceneHeight * 0.95;
+
+        for (double y = 0; y < limit; y++) {
+            yAxisList.add(centerX);
+            yAxisList.add(y + sceneHeight * 0.1);
+
+        }
+        Line line1 = new Line(centerX, sceneHeight * 0.1, centerX - sceneWidth * 0.03, sceneHeight * 0.22);
+        Line line2 = new Line(centerX, sceneHeight * 0.1, centerX + sceneWidth * 0.03, sceneHeight * 0.22);
+        Text text = new Text(limit + (sceneWidth * 0.2), sceneHeight * 0.1, "Y");
+        text.setFont(Font.font(fontSize));
+        pane.getChildren().addAll(line1, line2, text);
+    }
+
+    private String getXAxisLabel(double x) {
+        if (isRoughlyEqual(x, 0)) {
+            return "0";
+        } else if (isRoughlyEqual(x, 50)) {
+            return "π";
+        } else if (isRoughlyEqual(x, -50)) {
+            return "-π";
+        } else if (isRoughlyEqual(x, 100)) {
+            return "2π";
+        } else if (isRoughlyEqual(x, -100)) {
+            return "-2π";
+        }
+
+        return "";
+
+    }
+
+    private boolean isRoughlyEqual(double a, double b) {
+        return a - b < 0.01 && a - b > -0.01;
+    }
+
 }
+