// Based on Example 04-08 from "Getting Started with Processing" 
// by Reas & Fry.
int x = 20;
int limit = 800;
int boardWalkWidth = 760;

void setup() {
  background(0);
  size(960, 240);
  smooth();
  strokeWeight(2);
  stroke(255, 255, 255);
  frameRate(10);
}

void draw() {
  background(0);
  x = x - 1;
  limit = limit - 1;
  for (int i = x; i < limit; i += 20) {
    line(i, 10, i + i, 160);
  }
  line(x, 10, boardWalkWidth + x , 10);
  line(2 * x, 160, 2 * boardWalkWidth + 2 * x, 160);
}