/*
Jasper Travers

Walk: Version 02

Walk--Inspired by Walker from the introduction of "The Nature of Code" by Daniel Shiffman
http://natureofcode.com/book/introduction/

1/13/16
*/


Walker w;

boolean[] open;
boolean end = false;

void setup() {
  size(640, 360);
  background(255);
  frameRate(240);
  strokeWeight(1);

  //Boolean array which represents all the pixels of the canvas and one more on either side 
  //to prevent IndexOutOfBoundsExceptions
  open = new boolean[(height + 2) * (width + 2)];
  //sets open boolean array to true
  for (int i = 0; i < open.length; i++) {
    open[i] = true;
  }
  //initiates Walker object
  w = new Walker();  

}

//Steps to a new point, then draws in that point
void draw() {
  w.step();
  w.display();
}

//Press any key to pause/unpause the drawing
void keyPressed() {

  //saveFrame("Walk-#####.png");


  if (end == false) {
    end = true;
    noLoop();
  } else {
    end = false;
    loop();

  }
}

/*  Name:      Walker
 *  Purpose:   To define a Walker object and specify the random variables which influence the Walker's direction
 *             Builds color gradient.
 *  Params:    None
 */

class Walker {
  //location of object which, updated by random variables
  int x;
  int y;

  //random gen variables for Walker
  int choice = 0;
  int contLine = 0;

  //variables used for color gradient
  float randR = 0;
  float randG = 0;
  float randB = 0;

  //probabilities for right, left, down, up. prob4 = max of randintgen
  int prob1 = 250;
  int prob2 = 500;
  int prob3 = 750;
  int prob4 = 1000;


  Walker() {
    //initializes first Walker to middle of screen
    //x = width / 2;
    //y = height / 2;

    //variables used to place a new walker
    int randX = 0;
    int randY = 0;

    //randomizes placement of new walkers
    while (true) {
      randX = int(random(width / 16, 15 * width / 16));
      randY = int(random(height / 16, 15 * height / 16));
      //if a walker can be placed on that point
      if (open[randX * randY] == true) {
        break;
      }
    }

    //sets location of the walker
    x = randX;
    y = randY;
  }

  //draws point, color based on location
  void display() {
    float xf = x;
    float yf = y;
    float wf = width;
    float rgb = 255;

    //determines color gradient
    //red scales left to right
    randR = xf / wf * rgb;
    //blue scales top to bottom
    randB = yf / wf * rgb;
    //green scales right to left / 2
    randG = (wf - xf) / wf * rgb / 2;

    //draws point
    stroke(randR, randG, randB);
    point(x, y);
  }

  void step() {

    boolean right = false;
    boolean left = false;
    boolean up = false;
    boolean down = false;


    while (x > 0 && x < width && y > 0 && y < height) {

      //checks which directions the walker is allowed to draw
      right = open[width * y + (x + 1)];
      left = open[width * y + (x - 1)];
      down = open[width * (y + 1) + x];
      up = open[width * (y - 1) + x];
      break;

    }

    while (true) {

      //random variable to determine how long a line goes straight or until it is forced a new direction
      if (contLine < 10) {
        //random variable determines direction based on available directions
        choice = int(random(prob4));
      }

      contLine = int(random(100));

      //if I choose right, and can go right
      if (choice < prob1 && right == true) {

        open[width * y + x] = false;        //self
        open[width * y + (x - 1)] = false;  //left
        open[width * (y + 1) + x] = false;  //down
        open[width * (y - 1) + x] = false;  //up

        //go right
        x++; 
        break;
      }

      //if I choose left, and can go left
      else if (choice < prob2 && left == true) {

        open[width * y + (x + 1)] = false;  //right
        open[width * y + x] = false;        //self
        open[width * (y + 1) + x] = false;  //down
        open[width * (y - 1) + x] = false;  //up

        //go left
        x--;
        break;
      }

      //if I choose down, and can go down
      else if (choice < prob3 && down == true) {

        open[width * y + (x + 1)] = false;  //right
        open[width * y + (x - 1)] = false;  //left
        open[width * y + x] = false;        //self
        open[width * (y - 1) + x] = false;  //up

        //go down
        y++;
        break;
      }

      //if I choose up, and can go up
      else if (choice < prob4 && up == true) {

        open[width * y + (x + 1)] = false;  //right
        open[width * y + (x - 1)] = false;  //left
        open[width * (y + 1) + x] = false;  //down
        open[width * y + x] = false;        //self

        //go up
        y--;
        break;
      }
      //if trapped, make a new walker
      else if (right == false && left == false && up == false && down == false) {
        w = new Walker();
        break;
      }
    }
  }

  int getX() {
    return x;
  }

  int getY() {
    return y;
  }

}