67 lines
1.7 KiB
Java
67 lines
1.7 KiB
Java
import java.awt.*;
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import javax.swing.*;
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public class LargeUlamSpiral extends JPanel {
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public LargeUlamSpiral() {
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setPreferredSize(new Dimension(605, 605));
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setBackground(Color.white);
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}
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private boolean isPrime(int n) {
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if (n <= 2 || n % 2 == 0)
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return n == 2;
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for (int i = 3; i * i <= n; i += 2)
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if (n % i == 0)
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return false;
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return true;
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}
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@Override
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public void paintComponent(Graphics gg) {
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super.paintComponent(gg);
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Graphics2D g = (Graphics2D) gg;
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g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
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RenderingHints.VALUE_ANTIALIAS_ON);
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g.setColor(getForeground());
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double angle = 0.0;
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int x = 300, y = 300, dx = 1, dy = 0;
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for (int i = 1, step = 1, turn = 1; i < 40_000; i++) {
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if (isPrime(i))
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g.fillRect(x, y, 2, 2);
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x += dx * 3;
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y += dy * 3;
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if (i == turn) {
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angle += 90.0;
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if ((dx == 0 && dy == -1) || (dx == 0 && dy == 1))
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step++;
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turn += step;
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dx = (int) Math.cos(Math.toRadians(angle));
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dy = (int) Math.sin(Math.toRadians(-angle));
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}
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}
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}
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public static void main(String[] args) {
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SwingUtilities.invokeLater(() -> {
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JFrame f = new JFrame();
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f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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f.setTitle("Large Ulam Spiral");
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f.setResizable(false);
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f.add(new LargeUlamSpiral(), BorderLayout.CENTER);
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f.pack();
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f.setLocationRelativeTo(null);
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f.setVisible(true);
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});
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}
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}
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