class Soldier {
  // --------------------------------------------------------------------
  // CONSTANTS
  // --------------------------------------------------------------------
  int MIN_SIZE = 10;
  
  // --------------------------------------------------------------------
  // VARIABLES
  // --------------------------------------------------------------------
  float xPos, yPos;      
  float dX, dY;
  int strength;
  color colour;
  boolean isAlive;
  
  // --------------------------------------------------------------------
  // CONSTRUCTOR
  // --------------------------------------------------------------------
  Soldier(float x, float y) {
    xPos = x;
    yPos = y;
    strength = 1; 
    colour = color(random(100, 255), random(100, 255), random(100, 255)); 
    isAlive = true;
    
    // randomly set a start direction and speed
    dX = random(3);
    dY = random(3);
    if (random(1) < .5) dX *= -1;
    if (random(1) < .5) dY *= -1;
  }
  
  // --------------------------------------------------------------------
  // METHODS
  // --------------------------------------------------------------------
  /* moves the soldier and make it bounce off the walls */
  void move() {
    float radius = (strength+MIN_SIZE)/2.0;
    
    // if the soldier hit a wall, bounce back
    if (yPos+radius >= height) {
      // bottom wall
      dY *= -1;
    } else if (yPos-radius <= 0) {
      // top wall
      dY *= -1;
    }
    
    if (xPos+radius >= width) {
      // right wall
      dX *= -1;
    } else if (xPos-radius <= 0) {
      // left wall
      dX *= -1;
    }
    
    xPos += dX;
    yPos += dY;
  }

  /* draws the soldier */
  void draw() {
    // draw the shape first
    fill(colour);
    ellipse(xPos, yPos, strength+MIN_SIZE, strength+MIN_SIZE);
    
    // draw the number over it
    fill(0);
    text(strength, xPos, yPos);
  }
  
  /* checks if the current soldier collides with the passed other soldier */
  boolean collidesWith(Soldier other) {
    float distance = dist(xPos, yPos, other.xPos, other.yPos);
    float sumRadius = (strength+MIN_SIZE)/2.0 + (other.strength+MIN_SIZE)/2.0;

    if (distance < sumRadius) {
      return true;
    }
    return false;
  }
}