float angle = 0;
  float px = 0, py = 0;
  float amplitude = 30;
  float frequency = 0;
  float fillGap = 2.5;
  color c;
  
  void setup() {
    size(200, 200);
    background(200,200,200);
    noLoop();
  }
  
  void draw() {
    for (int i =- 75; i < height+75; i++){
      // Reset angle to 0, so waves stack properly
      angle = 0;
      // Increasing frequency causes more gaps
      frequency+=.006;
      for (float j=0; j<width+75; j++){
        py = i+sin(radians(angle))*amplitude;
        angle+=frequency;
        c =  color(abs(py-i)*255/amplitude, 255-abs(py-i)*255/amplitude, j*(255.0/(width+50)));
        // Hack to fill gaps. Raise value of fillGap if you increase frequency
        for (int filler = 0; filler<fillGap; filler++){
          set(int(j-filler), int(py)-filler, c);
          set(int(j), int(py), c);
          set(int(j+filler), int(py)+filler, c);
        }
      }
    }
  }