static int width = 80, height = 25;

static float[][] oldWave, newWave;

static final char[] CHARS = " .:-=+*#%@".toCharArray();

static Random rnd = new Random();

public static void main(String[] args) throws Exception {

oldWave = new float[height][width];

newWave = new float[height][width];

long delay = 50;

System.out.println("Press Ctrl+C to stop.\n");

for (int frame = 0; ; frame++) {

if (frame % 25 == 0) dropRandom(); // create ripples occasionally

simulate();

render(frame);

Thread.sleep(delay);

}

}

static void dropRandom() {

int r = rnd.nextInt(height - 4) + 2;

int c = rnd.nextInt(width - 4) + 2;

oldWave[r][c] = 5f; // splash intensity

}

static void simulate() {

for (int r = 1; r < height - 1; r++) {

for (int c = 1; c < width - 1; c++) {

// simple wave equation

newWave[r][c] = (

oldWave[r - 1][c] +

oldWave[r + 1][c] +

oldWave[r][c - 1] +

oldWave[r][c + 1]

) / 2 - newWave[r][c];

newWave[r][c] *= 0.985f; // damping

}

}

// swap

float[][] temp = oldWave;

oldWave = newWave;

newWave = temp;

}

static void render(int frame) {

StringBuilder sb = new StringBuilder("\033[H"); // move cursor home

for (int r = 0; r < height; r++) {

for (int c = 0; c < width; c++) {

float v = oldWave[r][c];

int idx = (int) Math.max(0, Math.min(CHARS.length - 1, (v + 5) / 10 * CHARS.length));

sb.append(CHARS[idx]);

}

sb.append('\n');

}

sb.append("Frame: ").append(frame).append('\n');

System.out.print(sb);

}