#include "library.h"

const int edge = 50;
const double timestep = 1.0;

struct actor
{ double posx, posy, speed;
  int colour;
  string name, success;
  actor * destination;
  
  void setpos(int x, int y)
  { posx = x + edge;
    posy = y + edge; }
    
  void setspeed(double s)
  { speed = s; }
  
  void setup(string n, int c, string s, actor * d)
  { name = n;
    colour = c;
    success = s;
    destination = d; }
    
  void update(double t)
  { double dx = destination->posx;
    double dy = destination->posy;
    double direction = atan((dx-posx)/(dy-posy));
    double changex = speed * t * sin(direction);
    double changey = speed * t * cos(direction);
    posx += changex;
    posy += changey; }

  void showself()
  { set_pen_color(colour);
    set_pen_width(3);
    move_to(posx, posy);
    draw_point(); }
};

struct universe
{ int width, length, topx, topy;
  actor cast[10];
  int castsize;

  universe(int l, int w)
  { width = w;
    length = l;
    topx = edge;
    topy = edge; }

  void make_window()
  { ::make_window(length+2*edge, width+2*edge); }
  
  void display()
  { set_pen_color(color::black);
    move_to(topx, topy);
    draw_to(topx+length, topy);
    draw_to(topx+length, topy+width);
    draw_to(topx, topy+width);
    draw_to(topx, topy);
    for (int i=0; i<castsize; i+=1)
      cast[i].showself(); }
      
  void update(double t)
  { for (int i=0; i<castsize; i+=1)
      cast[i].update(t); }
};

void main()
{ universe U(600, 500);
  actor boy, bull, tree;
  boy.setpos(200, U.width);
  bull.setpos(300, 50);
  tree.setpos(500, 200);
  boy.setspeed(21);
  bull.setspeed(35);
  tree.setspeed(0);
  boy.setup("boy", color::blue, "I'm safe", & tree);
  bull.setup("bull", color::red, "Chomp!", & boy);
  tree.setup("tree", color::green, "", NULL);
  U.cast[0] = boy;
  U.cast[1] = bull;
  U.cast[2] = tree;
  U.castsize = 3; 
  
  U.make_window();
  U.display();
  for (int i=0; i<10; i+=1)
  { U.update(timestep);
    U.display(); } }