int x=0;
void setup( ) {
  size(800, 100);
  background(0); 
  noLoop();
}

void draw( ) {
  smoke( );
  vehicle(color(0));
  x = x+1;
  vehicle(color(255));
}
void smoke( ) {
  noStroke( );
  float d;
  fill(255, 200, 0);
  ellipse((x+40)-(x%10), 50, max(10, random(20)), max(15, random(25)));
}
void vehicle(color c) {
  stroke(0);
  fill(c);
  rect(40+x, 40, 100, 20);
  triangle(140+x, 40, 155+x, 50, 140+x, 60);
  triangle(35+x, 40, 35+x, 30, 60+x, 40);
  triangle(35+x, 60, 35+x, 70, 60+x, 60);
}

void mousePressed( ) {
  loop( );
}

void mouseReleased( ) {
  noLoop( );
}