Polyspiral

Polyspiral is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

A Polyspiral is a spiral made of multiple line segments, whereby each segment is larger (or smaller) than the previous one by a given amount. Each segment also changes direction at a given angle.

The task: animate a series of polyspirals, by drawing a complete spiral then incrementing the angle, and (after clearing the background) drawing the next, and so on.

WHILE true

    x = width / 2
    y = height / 2
    set length

    FOR 1 TO 150
        drawline
        change direction by angle
        increment length
    ENDFOR

    increment angle MOD 360

If animation is not practical in your programming environment, you may show 3 frames from different stages of the animation instead.

Java

Works with: Java version 8

<lang java>import java.awt.*; import java.awt.event.ActionEvent; import javax.swing.*;

public class PolySpiral extends JPanel {

   double inc = 0;

   public PolySpiral() {
       setPreferredSize(new Dimension(640, 640));
       setBackground(Color.white);

       new Timer(40, (ActionEvent e) -> {
           inc = (inc + 0.05) % 360;
           repaint();
       }).start();
   }

   void drawSpiral(Graphics2D g, int len, double angleIncrement) {

       double x1 = getWidth() / 2;
       double y1 = getHeight() / 2;
       double angle = angleIncrement;

       for (int i = 0; i < 150; i++) {

           g.setColor(Color.getHSBColor(i / 150f, 1.0f, 1.0f));

           double x2 = x1 + Math.cos(angle) * len;
           double y2 = y1 - Math.sin(angle) * len;
           g.drawLine((int) x1, (int) y1, (int) x2, (int) y2);
           x1 = x2;
           y1 = y2;

           len += 3;

           angle = (angle + angleIncrement) % (Math.PI * 2);
       }
   }

   @Override
   public void paintComponent(Graphics gg) {
       super.paintComponent(gg);
       Graphics2D g = (Graphics2D) gg;
       g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
               RenderingHints.VALUE_ANTIALIAS_ON);

       drawSpiral(g, 5, Math.toRadians(inc));
   }

   public static void main(String[] args) {
       SwingUtilities.invokeLater(() -> {
           JFrame f = new JFrame();
           f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           f.setTitle("PolySpiral");
           f.setResizable(true);
           f.add(new PolySpiral(), BorderLayout.CENTER);
           f.pack();
           f.setLocationRelativeTo(null);
           f.setVisible(true);
       });
   }

}</lang>