class Vehicle {
 float x,y,rad,dx,dy;
 Vehicle prev;
 boolean inst = false;
 
 Vehicle(float ax, float ay, float arad){
  println("I'm a car");
  x = ax;
  y = ay;
  dx = random(-7,7);
  dy = random(-7,7);
  rad = arad;
  inst = true;
 }

 void update(){
  move();
  ellipse(x,y,rad,rad);
 }
 
 void calcds(){
  /*if(prev.inst){
   dx = 0.1(prev.x-x) 
  }*/
 }
 
 void move(){
  x+=dx;
  y+=dy;
  bounds();
 }
 
 void bounds(){
   if(y<0){
     y=0;
     dy = -1*dy;
   }
   else if(y>400){
     y=400;
     dy = -1*dy;
   }
  if(x<0){
     x=0;
     dx = -1*dx;
   }
   else if(x>400){
     x=400;
     dx = -1*dx;
   }   
 }
 
}