added MovingPolygon

ChrisMayfield · ChrisMayfield · commit 4eb70014ac4b · 2019-08-31T17:28:38.000-04:00
diff --git a/ch15/MovingPolygon.java b/ch15/MovingPolygon.java
@@ -0,0 +1,56 @@
+/**
+ * A polygon that moves around the screen.
+ */
+public class MovingPolygon extends RegularPolygon {
+
+    private int dx;
+    private int dy;
+
+    /**
+     * Constructs a moving polygon.
+     * 
+     * @param nsides the number of sides
+     * @param length length of each side
+     */
+    public MovingPolygon(int nsides, int length) {
+        super(nsides, length);
+        this.dx = 10;
+        this.dy = 5;
+    }
+
+    /**
+     * @param dx how many pixels to move left/right
+     */
+    public void setDx(int dx) {
+        this.dx = dx;
+    }
+
+    /**
+     * @param dy how many pixels to move up/down
+     */
+    public void setDy(int dy) {
+        this.dy = dy;
+    }
+
+    @Override
+    public void act() {
+
+        // edge detection
+        for (int i = 0; i < npoints; i++) {
+            if (xpoints[i] < 0 || xpoints[i] > 800) {
+                dx *= -1;
+                break;
+            }
+        }
+        for (int i = 0; i < npoints; i++) {
+            if (ypoints[i] < 0 || ypoints[i] > 600) {
+                dy *= -1;
+                break;
+            }
+        }
+
+        // move one step
+        translate(dx, dy);
+    }
+
+}
diff --git a/ch15/RegularPolygon.java b/ch15/RegularPolygon.java
@@ -73,7 +73,7 @@ public void act() {
 
     @Override
     public void draw(Graphics g) {
-        System.out.println(this);
+        // System.out.println(this);
         g.drawPolygon(this);
     }
 
diff --git a/ch15/Sim3.java b/ch15/Sim3.java
@@ -0,0 +1,44 @@
+import javax.swing.JFrame;
+
+/**
+ * Example simulation of stationary objects.
+ */
+public class Sim3 {
+
+    /**
+     * Test program that draws a few polygons.
+     * 
+     * @param args command-line arguments
+     */
+    public static void main(String[] args) {
+
+        MovingPolygon mp = new MovingPolygon(8, 30);
+        mp.translate(100, 100);
+        Drawing drawing = new Drawing(800, 600);
+        drawing.add(mp);
+
+        JFrame frame = new JFrame("Drawing");
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.setResizable(false);
+        frame.add(drawing);
+        frame.pack();
+        frame.setVisible(true);
+
+        // main simulation loop
+        while (true) {
+
+            // update the drawing
+            drawing.nextact();
+            drawing.repaint();
+
+            // delay the simulation
+            try {
+                Thread.sleep(1000 / 50);
+                frame.getToolkit().sync();
+            } catch (InterruptedException e) {
+                // do nothing
+            }
+        }
+    }
+
+}
diff --git a/ch15/Sim4.java b/ch15/Sim4.java
@@ -0,0 +1,45 @@
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+
+import javax.swing.JFrame;
+
+/**
+ * Example simulation of stationary objects.
+ */
+public class Sim4 implements ActionListener {
+
+    private Drawing drawing;
+    private JFrame frame;
+
+    public Sim4() {
+        MovingPolygon mp = new MovingPolygon(8, 30);
+        mp.translate(100, 100);
+        drawing = new Drawing(800, 600);
+        drawing.add(mp);
+
+        frame = new JFrame("Drawing");
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.setResizable(false);
+        frame.add(drawing);
+        frame.pack();
+        frame.setVisible(true);
+    }
+
+    /**
+     * Test program that draws a few polygons.
+     *
+     * @param args command-line arguments
+     */
+    public static void main(String[] args) {
+        Sim4 sim = new Sim4();
+        new javax.swing.Timer(1000 / 50, sim).start();
+    }
+
+    @Override
+    public void actionPerformed(ActionEvent e) {
+        drawing.nextact();
+        drawing.repaint();
+        frame.getToolkit().sync();
+    }
+
+}

Original file line number	Diff line number	Diff line change
`@@ -73,7 +73,7 @@ public void act() {`
`73`	`73`
`74`	`74`	`@Override`
`75`	`75`	`public void draw(Graphics g) {`
`76`		`- System.out.println(this);`
	`76`	`+ // System.out.println(this);`
`77`	`77`	`g.drawPolygon(this);`
`78`	`78`	`}`
`79`	`79`