// chaosGame.C
//
// Written 11 Feb 96 by Max Hailperin <max@gac.edu>
//
// This program plays simple versions of the "chaos game" in which the orbit
//  of a point is plotted as it moves some specified fraction of the way towards
//  a randomly chosen vertex at each iteration, where the vertices are equally
//  spaced and there are a specified number of them.
//
// For a simple but startling demo, try using 3 vertices and a compression of .5,
//  i.e., each iteration the point moves half way towards a randomly chosen vertex
//  of an equilateral triangle.  You can start with the initial point anywhere,
//  though if it is inside the triangle its behavior will more quickly become
//  "normal".  Assuming you start inside the triangle, you can ask to not show the
//  first maybe 8 or 10 iterations and see the pattern clearly.
//
// This version of the program incorporates some rather crude user interface,
//  namely waiting for the user to press enter once the drawing window is
//  displayed properly before it starts to draw on it, as a precaution in case
//  the DrawingWindow class is implemented using a simplistic implementation
//  that can't deal with drawing "off screen" and copying that onto the
//  on-screen window when appropriate.
//
// A similar wait-for-enter-key at the end prevents the window from vanishing
//  before the user gets to see it, since windows would go away on program
//  exit in most obvious implementations of the DrawingWindow abstraction.
//
// For more information, see  http://math.bu.edu/DYSYS/chaos-game/chaos-game.html

#include <iostream.h>
#include <stdlib.h>
#include "Vector.h"
#include "DrawingWindow.h"
#include "pseudoRandom.h"

Vector makeVectorPolar(float radius, float angle); // declared here, needs defining

Vector get_vec(int identifyingNumber); // snarf definition from Wang's book

Vector fractionFromTo(float f, Vector p1, Vector p2)
     // returns the Vector for the point the fraction f of the way from p1 to p2
{
  return p2*f + p1*(1-f);
}

void readThroughNewline(){
  char c;
  while(cin.get(c) && c != '\n')
    ;
}  

int main(){
  const int maxVertices = 20;
  int numVertices;
  cout << "How many vertices? ";
  cin >> numVertices;
  if(numVertices > maxVertices){
    cerr << "Sorry, this program is set up for at most " << maxVertices
      << " vertices.\n";
    exit(1);
  }
  Vector vertices[maxVertices];
  for(int i = 0; i < numVertices; i++)
    vertices[i] = makeVectorPolar(1, 2*3.14159*i/numVertices);
  float compression;
  cout << "What compression? ";
  cin >> compression;
  int iterations;
  cout << "How many iterations? ";
  cin >> iterations;
  int hiddenIterations;
  cout << "How many initial iterations should not be displayed? ";
  cin >> hiddenIterations;
  cout << "Enter staring point.\n";
  Vector point = get_vec(0);
  DrawingWindow win;
  readThroughNewline(); // to get rid of the newline at end of last input
  cout << "Press enter once window is visible.\n";
  readThroughNewline(); // to wait for this, due to lack of redrawing support
  for(i = 1; i <= iterations; i++){
    point = fractionFromTo(compression, vertices[pseudoRandom(numVertices)], point);
    if(i > hiddenIterations)
      point.drawAsPointOn(win);
  }
  cout << "Press enter when ready to exit program.\n";
  readThroughNewline(); // to wait for this, since window goes away on exit
  return 0;
}