///////////////////////////////////////
/**************************************
 //www.geneatcg.com/
  
 Processing 101 - 05
 Wriiten by Gene Kao
 Date --- 2013/04/16
  
 **************************************/
///////////////////////////////////////
 
 
Pipe[][] grids;
 
int width = 650; 
int height = 450;
int x = 20; 
int y = 15;
int gridx = width/x; 
int gridy = height/y; 
int w = 15; 
 
void setup() {
 
  size(width, height);
  smooth(); 
  background(200);
  rectMode(CENTER);
  frameRate(10);
 
  grids = new Pipe[2*x][2*y];
 
  for (int i = 0; i < 2*x-1; i++) {
    for (int j = 0; j < 2*y-1; j++) {
      if (i % 2 == 0 || j % 2 ==0) {
        PVector pos = new PVector(i*gridx/2+gridx/2, j*gridy/2+gridy/2);
        grids[i][j] = new Pipe(pos, i, j, false);
      } 
      else {
        PVector o = new PVector(0, 0);
        grids[i][j] = new Pipe(o, i, j, false);
      }
    }
  }
  rand();
}
 
void draw() {
 
  background(200);
 
  for (int i = 0; i < 2*x-1; i++) {
    for (int j = 0; j < 2*y-1; j++) {
      if (i % 2 == 0 || j % 2 ==0) {
        if (i % 2 == 0 && j % 2 ==0) fill(255, 0, 0);
        else fill(255);
        strokeWeight(1);
        ellipse(grids[i][j].loc.x, grids[i][j].loc.y, 5, 5);
 
        if (i % 2 == 0 && j % 2 ==0) {
 
          strokeWeight(w);
          grids[i][j].testLeftUP();
        }
      }
    }
  }
}
 
void mousePressed() {
  startover();
  rand();
}
 
 
void rand() {
  for (int i = 0; i < 2*x-1; i++) {
    for (int j = 0; j < 2*y-1; j++) {
      if (i % 2 == 0 || j % 2 ==0) {
        if (i % 2 == 0 && j % 2 ==0) fill(255, 0, 0);
        else fill(255);
        //strokeWeight(1);
        //ellipse(grids[i][j].loc.x, grids[i][j].loc.y, 5, 5);
        if (i % 2 == 0 && j % 2 ==0) {
 
          grids[i][j].randomize();
        }
      }
    }
  }
}
 
void startover() {
  for (int i = 0; i < 2*x-1; i++) {
    for (int j = 0; j < 2*y-1; j++) {
      grids[i][j].initial();
    }
  }
}
 
 
 
class Pipe {
 
  PVector loc; 
  int i; 
  int j; 
  boolean taken = false;
 
  Pipe(PVector loc, int i, int j, boolean taken) {
    this.loc = loc; 
    this.i = i; 
    this.j = j; 
    this.taken = taken;
  }
 
  void starter() {
    if (i == 0 && j == 0) {
      if (random(1)>0.5) {
        grids[0][1].taken = true;
      }
      if (random(1)>0.5) {
        grids[1][0].taken = true;
      }
    }
  }
 
  void testLeftUP() {
 
    if ( ( i > 0 && j > 0 ) && (i<2*x-2 && j<2*y-2) ) {
 
      if (grids[i][j-1].taken == true) {
        line(loc.x, loc.y, grids[i][j-2].loc.x, grids[i][j-2].loc.y);
      }
      if (grids[i-1][j].taken == true) {
        line(loc.x, loc.y, grids[i-2][j].loc.x, grids[i-2][j].loc.y);
      }
    }
  }
 
  void randomize() {
 
    if ((j>0 && j < 2*y-2) && (i>0 && i < 2*x-2)) {
 
      if (random(1)>0.5) {
        grids[i][j+1].taken = true;
      }
      if (random(1)>0.5) {
        grids[i+1][j].taken = true;
      }
    }
  }
 
  void initial() {
    grids[i][j].taken = false;
  }
}