もじゃ

moja.pde

float offsetX;
float offsetY;
float endY;
float posX;
float posY;
float oldX;
float oldY;
float noise = 0;

void setup() {
  size(800, 800);
  background(255, 255, 255);
  reset();
}

void draw() {
  for (int i = 0; i < 100; i++) {
    drawLine();
  }
}

void reset() {
  posX = oldX = 0;
  posY = oldY = 0;
  offsetX = 0.5 + random(-1, 1) * 0.1;
  offsetY = random(0, 0.3);
  endY = min(1, offsetY + random(0.1, 1));
}

void drawLine() {
  float ratio = map(offsetY / endY, 0, 1, 0.5, 1);
  
  posX += 0.005 * ratio * (noise(noise) - 0.5);
  posY += 0.005 * ratio * (noise(noise + 1000) - 0.5);
  
  line((oldX + offsetX) * width, (oldY + offsetY) * height, (posX + offsetX) * width, (posY + offsetY) * height);
  
  if (offsetY >= endY) {
    reset();
  }
  
  offsetY += 0.001;
  oldX = posX;
  oldY = posY;
  noise += 0.01;
}

Run on http://www.processing.org/