03. Creating a Snake Game.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# <center><u>Introduction to curses in Python (Part-3)</u></center><br><center>Creating a Snake Game</center>\n",
    "\n",
    "![](images/5.png)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 1. Creating a game box area\n",
    "\n",
    "Instead of covering the whole screen, we would like to use a rectangular box as our game area. Remaining parts can be used for showing some other useful info like score, remaining attempts, etc.\n",
    "\n",
    "> The `curses.textpad` module provides a `Textbox` class that handles elementary text editing in a curses window. The module also provides a rectangle-drawing function useful for framing text boxes or for other purposes.\n",
    "\n",
    "\n",
    "### `textpad.rectangle(stdscr, uly, ulx, lry, lrx)`\n",
    "\n",
    "Draws a rectangle. The first argument must be a window object; the remaining arguments are coordinates relative to that window. The second and third arguments are the y and x coordinates of the upper left hand corner of the rectangle to be drawn; the fourth and fifth arguments are the y and x coordinates of the lower right hand corner.\n",
    "\n",
    "![](images/6.png)\n",
    "\n",
    "\n",
    "From the diagram shown above, the game area box has coordinates:\n",
    "- upper-left corner: `(3,3)`\n",
    "- lower-right corner: `(sw-3, sh-3)`\n",
    "\n",
    "where `sh` and `sw` are screen height and width, respectively.\n",
    "\n",
    "So, we define box coordinates as:\n",
    "\n",
    "```python\n",
    "box = [[3,3], [sh-3, sw-3]]\n",
    "```\n",
    "\n",
    "**Note:** curses follows `(y,x)` system to represent coordinates.\n",
    "\n",
    "Now, rectangle can be drawn as:\n",
    "\n",
    "```python\n",
    "textpad.rectangle(stdscr, box[0][0], box[0][1], box[1][0], box[1][1])\n",
    "```\n",
    "\n",
    "## Example 7\n",
    "\n",
    "```python\n",
    "import curses\n",
    "from curses import textpad\n",
    "\n",
    "\n",
    "def main(stdscr):\n",
    "\tcurses.curs_set(0)\n",
    "\tsh, sw = stdscr.getmaxyx()\n",
    "\tbox = [[3,3], [sh-3, sw-3]]\n",
    "\ttextpad.rectangle(stdscr, box[0][0], box[0][1], box[1][0], box[1][1])\n",
    "\tstdscr.getch()\n",
    "\n",
    "\n",
    "curses.wrapper(main)\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Let's create the snake game now!\n",
    "\n",
    "## Example 8\n",
    "\n",
    "```python\n",
    "import random\n",
    "import curses\n",
    "from curses import textpad\n",
    "\n",
    "OPPOSITE_DIRECTION_DICT = {\n",
    "    curses.KEY_UP: curses.KEY_DOWN,\n",
    "    curses.KEY_DOWN: curses.KEY_UP,\n",
    "    curses.KEY_RIGHT: curses.KEY_LEFT,\n",
    "    curses.KEY_LEFT: curses.KEY_RIGHT\n",
    "}\n",
    "\n",
    "DIRECTIONS_LIST = [curses.KEY_RIGHT, curses.KEY_LEFT, curses.KEY_DOWN, curses.KEY_UP]\n",
    "\n",
    "\n",
    "def create_food(snake, box):\n",
    "\t\"\"\"Simple function to find coordinates of food which is inside box and not on snake body\"\"\"\n",
    "\tfood = None\n",
    "\twhile food is None:\n",
    "\t\tfood = [random.randint(box[0][0]+1, box[1][0]-1), \n",
    "\t\trandom.randint(box[0][1]+1, box[1][1]-1)]\n",
    "\t\tif food in snake:\n",
    "\t\t\tfood = None\n",
    "\treturn food\n",
    "\n",
    "\n",
    "def main(stdscr):\n",
    "\t# initial settings\n",
    "\tcurses.curs_set(0)\n",
    "\tstdscr.nodelay(1)\n",
    "\tstdscr.timeout(100)\n",
    "\n",
    "\t# create a game box\n",
    "\tsh, sw = stdscr.getmaxyx()\n",
    "\tbox = [[3,3], [sh-3, sw-3]]  # [[ul_y, ul_x], [dr_y, dr_x]]\n",
    "\ttextpad.rectangle(stdscr, box[0][0], box[0][1], box[1][0], box[1][1])\n",
    "\t\n",
    "\t# create snake and set initial direction\n",
    "\tsnake = [[sh//2, sw//2+1], [sh//2, sw//2], [sh//2, sw//2-1]]\n",
    "\tdirection = curses.KEY_RIGHT\n",
    "\n",
    "\t# draw snake\n",
    "\tfor y,x in snake:\n",
    "\t\tstdscr.addstr(y, x, '#')\n",
    "\n",
    "\t# create food\n",
    "\tfood = create_food(snake, box)\n",
    "\tstdscr.addstr(food[0], food[1], '*')\n",
    "\n",
    "\t# print score\n",
    "\tscore = 0\n",
    "\tscore_text = \"Score: {}\".format(score)\n",
    "\tstdscr.addstr(1, sw//2 - len(score_text)//2, score_text)\n",
    "\n",
    "\twhile 1:\n",
    "\t\t# non-blocking input\n",
    "\t\tkey = stdscr.getch()\n",
    "\n",
    "\t\t# set direction if user pressed any arrow key and that key is not opposite of current direction\n",
    "        if key in DIRECTIONS_LIST and key != OPPOSITE_DIRECTION_DICT[direction]:\n",
    "            direction = key\n",
    "\t\t\t\n",
    "\n",
    "\t\t# find next position of snake head\n",
    "\t\thead = snake[0]\n",
    "\t\tif direction == curses.KEY_RIGHT:\n",
    "\t\t\tnew_head = [head[0], head[1]+1]\n",
    "\t\telif direction == curses.KEY_LEFT:\n",
    "\t\t\tnew_head = [head[0], head[1]-1]\n",
    "\t\telif direction == curses.KEY_DOWN:\n",
    "\t\t\tnew_head = [head[0]+1, head[1]]\n",
    "\t\telif direction == curses.KEY_UP:\n",
    "\t\t\tnew_head = [head[0]-1, head[1]]\n",
    "\n",
    "\t\t# insert and print new head\n",
    "\t\tstdscr.addstr(new_head[0], new_head[1], '#')\n",
    "\t\tsnake.insert(0, new_head)\n",
    "\t\t\n",
    "\t\t# if sanke head is on food\n",
    "\t\tif snake[0] == food:\n",
    "\t\t\t# update score\n",
    "\t\t\tscore += 1\n",
    "\t\t\tscore_text = \"Score: {}\".format(score)\n",
    "\t\t\tstdscr.addstr(1, sw//2 - len(score_text)//2, score_text)\n",
    "\t\t\t\n",
    "\t\t\t# create new food\n",
    "\t\t\tfood = create_food(snake, box)\n",
    "\t\t\tstdscr.addstr(food[0], food[1], '*')\n",
    "\n",
    "\t\t\t# increase speed of game\n",
    "\t\t\tstdscr.timeout(100 - (len(snake)//3)%90)\n",
    "\t\telse:\n",
    "\t\t\t# shift snake's tail\n",
    "\t\t\tstdscr.addstr(snake[-1][0], snake[-1][1], ' ')\n",
    "\t\t\tsnake.pop()\n",
    "\n",
    "\t\t# conditions for game over\n",
    "\t\tif (snake[0][0] in [box[0][0], box[1][0]] or \n",
    "\t\t\tsnake[0][1] in [box[0][1], box[1][1]] or \n",
    "\t\t\tsnake[0] in snake[1:]):\n",
    "\t\t\tmsg = \"Game Over!\"\n",
    "\t\t\tstdscr.addstr(sh//2, sw//2-len(msg)//2, msg)\n",
    "\t\t\tstdscr.nodelay(0)\n",
    "\t\t\tstdscr.getch()\n",
    "\t\t\tbreak\n",
    "\n",
    "curses.wrapper(main)\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "![](images/7.jpeg)"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.8.5"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}