int num = 2000;
  int range = 6;
  
  float[] ax = new float[num];
  float[] ay = new float[num]; 
  
  void setup() 
  {
    size(640, 360);
    for(int i = 0; i < num; i++) {
      ax[i] = width/2;
      ay[i] = height/2;
    }
    frameRate(30);
  }
  
  void draw() 
  {
    background(51);
    
    // Shift all elements 1 place to the left
    for(int i = 1; i < num; i++) {
      ax[i-1] = ax[i];
      ay[i-1] = ay[i];
    }
  
    // Put a new value at the end of the array
    ax[num-1] += random(-range, range);
    ay[num-1] += random(-range, range);
  
    // Constrain all points to the screen
    ax[num-1] = constrain(ax[num-1], 0, width);
    ay[num-1] = constrain(ay[num-1], 0, height);
    
    // Draw a line connecting the points
    for(int i=1; i<num; i++) {    
      float val = float(i)/num * 204.0 + 51;
      stroke(val);
      line(ax[i-1], ay[i-1], ax[i], ay[i]);
    }
  }