Initial data commit

Task/Plasma-effect/Java/plasma-effect.java

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+import java.awt.*;
+import java.awt.event.*;
+import java.awt.image.*;
+import static java.awt.image.BufferedImage.*;
+import static java.lang.Math.*;
+import javax.swing.*;
+
+public class PlasmaEffect extends JPanel {
+    float[][] plasma;
+    float hueShift = 0;
+    BufferedImage img;
+
+    public PlasmaEffect() {
+        Dimension dim = new Dimension(640, 640);
+        setPreferredSize(dim);
+        setBackground(Color.white);
+
+        img = new BufferedImage(dim.width, dim.height, TYPE_INT_RGB);
+        plasma = createPlasma(dim.height, dim.width);
+
+        // animate about 24 fps and shift hue value with every frame
+        new Timer(42, (ActionEvent e) -> {
+            hueShift = (hueShift + 0.02f) % 1;
+            repaint();
+        }).start();
+    }
+
+    float[][] createPlasma(int w, int h) {
+        float[][] buffer = new float[h][w];
+
+        for (int y = 0; y < h; y++)
+            for (int x = 0; x < w; x++) {
+
+                double value = sin(x / 16.0);
+                value += sin(y / 8.0);
+                value += sin((x + y) / 16.0);
+                value += sin(sqrt(x * x + y * y) / 8.0);
+                value += 4; // shift range from -4 .. 4 to 0 .. 8
+                value /= 8; // bring range down to 0 .. 1
+
+                // requires VM option -ea
+                assert (value >= 0.0 && value <= 1.0) : "Hue value out of bounds";
+
+                buffer[y][x] = (float) value;
+            }
+        return buffer;
+    }
+
+    void drawPlasma(Graphics2D g) {
+        int h = plasma.length;
+        int w = plasma[0].length;
+        for (int y = 0; y < h; y++)
+            for (int x = 0; x < w; x++) {
+                float hue = hueShift + plasma[y][x] % 1;
+                img.setRGB(x, y, Color.HSBtoRGB(hue, 1, 1));
+            }
+        g.drawImage(img, 0, 0, null);
+    }
+
+    @Override
+    public void paintComponent(Graphics gg) {
+        super.paintComponent(gg);
+        Graphics2D g = (Graphics2D) gg;
+        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
+                RenderingHints.VALUE_ANTIALIAS_ON);
+
+        drawPlasma(g);
+    }
+
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(() -> {
+            JFrame f = new JFrame();
+            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            f.setTitle("Plasma Effect");
+            f.setResizable(false);
+            f.add(new PlasmaEffect(), BorderLayout.CENTER);
+            f.pack();
+            f.setLocationRelativeTo(null);
+            f.setVisible(true);
+        });
+    }
+}