Chapter 1: Tank Game Course

var TankGame = (function() {
  var TARGET_WIDTH = 801; // Desired width
  var TARGET_HEIGHT = 601;
  var WIDTH; // Actual width of game, scaled to fit screen
  var HEIGHT;
  var GUI_HEIGHT = 150;
  var DEBUG = false;
  // WASD
  var P1_UP = 87;
  var P1_DOWN = 83;
  var P1_LEFT = 65;
  var P1_RIGHT = 68;
  var P1_FIRE = 49;

  // Arrow keys
  var P2_UP = 38;
  var P2_DOWN = 40;
  var P2_LEFT = 37;
  var P2_RIGHT = 39;
  var P2_FIRE = 189;

  // Other settings
  var TANK_SIZE = 15;
  var TANK_SPEED = 1;
  var TANK_TURN_SPEED = 5;
  var WALL_WIDTH = 2;
  var CELL_SIZE = 50;
  var RESET_COUNTER_MAX = 200;
  var EPSILON = 0.001;


  var MAX_DIST_FOR_COLLISIONS = 2; // (this is multiplied by CELL_SIZE)
  var TANK_P1, TANK_P2;
  var CELLS_X, CELLS_Y;
  var CANVAS, CTX, KEYSTATE, GAME_OBJECTS;
  var PRERENDERED_CANVAS, PRERENDERED_CTX, PRERENDERED_REDRAW_NEEDED;
  var GUI_REDRAW_NEEDED;
  var END_ROUND = false;
  var RESET_COUNTER;

  var P1 = 1;
  var P2 = 2;
  var P1_SCORE = 0;
  var P2_SCORE = 0;