int nlines = 5;
int nsamples = 50;

float[][] xs = new float[nlines][nsamples];

int max_height;
int pixels_per_sample;


void setup() {
  size(800,400);
  smooth();
  colorMode(HSB, 100);
  
  max_height = height / nlines;
  pixels_per_sample = width / nsamples;

  for(int i=0; i<nlines; i++) {
    for(int j=0; j<nsamples; j++) {
      xs[i][j] = noise(i*nsamples*random(1)+ j*0.3) * max_height;
    }
  }
}




void draw() {
  background(50);
  //curveTightness(map(mouseX, 0, width, -10, 10));
  float[] sums = new float[nsamples];
  for(int i=0; i<nsamples; i++) {sums[i]=0;}
  
  for(int line=0; line<nlines; line++) {
    fill(line*(100/nlines), 50, 50, 40);
    stroke(75);
    
    float[][] ys = new float[2][nsamples];
    
    beginShape();
    int x;
    for(x=0; x<nsamples; x++) {
      ys[0][x] = sums[x];
      sums[x] += xs[line][x];
      ys[1][x] = sums[x];
    }
    for(x=0; x<nsamples; x++)
      vertex(x*pixels_per_sample, height-ys[1][x]);
    for(x--; x >= 0; x--)
      vertex(x*pixels_per_sample, height-ys[0][x]);
    endShape(CLOSE);
  }
}