Plant vs Zombies Python Game: State Management and Core Modules Overview

The document showcases a Python-based Plant vs Zombies game built with Pygame, focusing on the modular state management system that drives menus, gameplay levels, and victory/defeat screens.

state/tool.py defines the core State abstract class and the Control class that handles the game loop, event processing, state transitions, and utility functions for loading graphics and assets.

import os
import json
from abc import abstractmethod
import pygame as pg
from . import constants as c

class State():
    def __init__(self):
        self.start_time = 0.0
        self.current_time = 0.0
        self.done = False
        self.next = None
        self.persist = {}
    @abstractmethod
    def startup(self, current_time, persist):
        ''abstract method''
    def cleanup(self):
        self.done = False
        return self.persist
    @abstractmethod
    def update(self, surface, keys, current_time):
        ''abstract method''

class Control():
    def __init__(self):
        self.screen = pg.display.get_surface()
        self.done = False
        self.clock = pg.time.Clock()
        self.fps = 60
        self.keys = pg.key.get_pressed()
        self.mouse_pos = None
        self.mouse_click = [False, False]  # [left, right]
        self.current_time = 0.0
        self.state_dict = {}
        self.state_name = None
        self.state = None
        self.game_info = {c.CURRENT_TIME:0.0, c.LEVEL_NUM:c.START_LEVEL_NUM}
    def setup_states(self, state_dict, start_state):
        self.state_dict = state_dict
        self.state_name = start_state
        self.state = self.state_dict[self.state_name]
        self.state.startup(self.current_time, self.game_info)
    def update(self):
        self.current_time = pg.time.get_ticks()
        if self.state.done:
            self.flip_state()
        self.state.update(self.screen, self.current_time, self.mouse_pos, self.mouse_click)
        self.mouse_pos = None
        self.mouse_click[0] = False
        self.mouse_click[1] = False
    def flip_state(self):
        previous, self.state_name = self.state_name, self.state.next
        persist = self.state.cleanup()
        self.state = self.state_dict[self.state_name]
        self.state.startup(self.current_time, persist)
    def event_loop(self):
        for event in pg.event.get():
            if event.type == pg.QUIT:
                self.done = True
            elif event.type == pg.KEYDOWN:
                self.keys = pg.key.get_pressed()
            elif event.type == pg.KEYUP:
                self.keys = pg.key.get_pressed()
            elif event.type == pg.MOUSEBUTTONDOWN:
                self.mouse_pos = pg.mouse.get_pos()
                self.mouse_click[0], _, self.mouse_click[1] = pg.mouse.get_pressed()
                print('pos:', self.mouse_pos, ' mouse:', self.mouse_click)
    def main(self):
        while not self.done:
            self.event_loop()
            self.update()
            pg.display.update()
            self.clock.tick(self.fps)
        print('game over')

def get_image(sheet, x, y, width, height, colorkey=c.BLACK, scale=1):
    image = pg.Surface([width, height])
    rect = image.get_rect()
    image.blit(sheet, (0, 0), (x, y, width, height))
    image.set_colorkey(colorkey)
    image = pg.transform.scale(image, (int(rect.width*scale), int(rect.height*scale)))
    return image

def load_image_frames(directory, image_name, colorkey, accept):
    frame_list = []
    tmp = {}
    index_start = len(image_name) + 1
    frame_num = 0
    for pic in os.listdir(directory):
        name, ext = os.path.splitext(pic)
        if ext.lower() in accept:
            index = int(name[index_start:])
            img = pg.image.load(os.path.join(directory, pic))
            if img.get_alpha():
                img = img.convert_alpha()
            else:
                img = img.convert()
                img.set_colorkey(colorkey)
            tmp[index]= img
            frame_num += 1
    for i in range(frame_num):
        frame_list.append(tmp[i])
    return frame_list

def load_all_gfx(directory, colorkey=c.WHITE, accept=(' .png', '.jpg', '.bmp', '.gif')):
    graphics = {}
    for name1 in os.listdir(directory):
        dir1 = os.path.join(directory, name1)
        if os.path.isdir(dir1):
            for name2 in os.listdir(dir1):
                dir2 = os.path.join(dir1, name2)
                if os.path.isdir(dir2):
                    for name3 in os.listdir(dir2):
                        dir3 = os.path.join(dir2, name3)
                        if os.path.isdir(dir3):
                            image_name, _ = os.path.splitext(name3)
                            graphics[image_name] = load_image_frames(dir3, image_name, colorkey, accept)
                        else:
                            image_name, _ = os.path.splitext(name2)
                            graphics[image_name] = load_image_frames(dir2, image_name, colorkey, accept)
                            break
                else:
                    name, ext = os.path.splitext(name2)
                    if ext.lower() in accept:
                        img = pg.image.load(dir2)
                        if img.get_alpha():
                            img = img.convert_alpha()
                        else:
                            img = img.convert()
                            img.set_colorkey(colorkey)
                        graphics[name] = img
    return graphics

def loadZombieImageRect():
    file_path = os.path.join('source','data','entity','zombie.json')
    f = open(file_path)
    data = json.load(f)
    f.close()
    return data[c.ZOMBIE_IMAGE_RECT]

def loadPlantImageRect():
    file_path = os.path.join('source','data','entity','plant.json')
    f = open(file_path)
    data = json.load(f)
    f.close()
    return data[c.PLANT_IMAGE_RECT]

pg.init()
pg.display.set_caption(c.ORIGINAL_CAPTION)
SCREEN = pg.display.set_mode(c.SCREEN_SIZE)
GFX = load_all_gfx(os.path.join('resources','graphics'))
ZOMBIE_RECT = loadZombieImageRect()
PLANT_RECT = loadPlantImageRect()

state/constants.py contains all game-wide constants such as screen dimensions, grid layout, color definitions, game object identifiers, health values, timing intervals, and state identifiers used throughout the engine.

START_LEVEL_NUM = 1
ORIGINAL_CAPTION = 'Plant VS Zombies Game'
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
SCREEN_SIZE = (SCREEN_WIDTH, SCREEN_HEIGHT)
GRID_X_LEN = 9
GRID_Y_LEN = 5
GRID_X_SIZE = 80
GRID_Y_SIZE = 100
WHITE = (255, 255, 255)
NAVYBLUE = (60, 60, 100)
SKY_BLUE = (39, 145, 251)
BLACK = (0, 0, 0)
LIGHTYELLOW = (234, 233, 171)
RED = (255, 0, 0)
PURPLE = (255, 0, 255)
GOLD = (255, 215, 0)
GREEN = (0, 255, 0)
SIZE_MULTIPLIER = 1.3
CURRENT_TIME = 'current time'
LEVEL_NUM = 'level num'
MAIN_MENU = 'main menu'
LOAD_SCREEN = 'load screen'
GAME_LOSE = 'game los'
GAME_VICTORY = 'game victory'
LEVEL = 'level'
MAIN_MENU_IMAGE = 'MainMenu'
OPTION_ADVENTURE = 'Adventure'
GAME_LOOSE_IMAGE = 'GameLoose'
GAME_VICTORY_IMAGE = 'GameVictory'
BACKGROUND_NAME = 'Background'
BACKGROUND_TYPE = 'background_type'
INIT_SUN_NAME = 'init_sun_value'
ZOMBIE_LIST = 'zombie_list'
MAP_EMPTY = 0
MAP_EXIST = 1
BACKGROUND_OFFSET_X = 220
MAP_OFFSET_X = 35
MAP_OFFSET_Y = 100
CHOOSEBAR_TYPE = 'choosebar_type'
CHOOSEBAR_STATIC = 0
CHOOSEBAR_MOVE = 1
CHOSSEBAR_BOWLING = 2
MENUBAR_BACKGROUND = 'ChooserBackground'
MOVEBAR_BACKGROUND = 'MoveBackground'
PANEL_BACKGROUND = 'PanelBackground'
START_BUTTON = 'StartButton'
CARD_POOL = 'card_pool'
MOVEBAR_CARD_FRESH_TIME = 6000
CARD_MOVE_TIME = 60
PLANT_IMAGE_RECT = 'plant_image_rect'
CAR = 'car'
SUN = 'Sun'
SUNFLOWER = 'SunFlower'
PEASHOOTER = 'Peashooter'
SNOWPEASHOOTER = 'SnowPea'
WALLNUT = 'WallNut'
CHERRYBOMB = 'CherryBomb'
THREEPEASHOOTER = 'Threepeater'
REPEATERPEA = 'RepeaterPea'
CHOMPER = 'Chomper'
CHERRY_BOOM_IMAGE = 'Boom'
PUFFSHROOM = 'PuffShroom'
POTATOMINE = 'PotatoMine'
SQUASH = 'Squash'
SPIKEWEED = 'Spikeweed'
JALAPENO = 'Jalapeno'
SCAREDYSHROOM = 'ScaredyShroom'
SUNSHROOM = 'SunShroom'
ICESHROOM = 'IceShroom'
HYPNOSHROOM = 'HypnoShroom'
WALLNUT_BOWLING = 'WallNutBowling'
REDWALLNUT_BOWLING = 'RedWallNutBowling'
PLANT_HEALTH = 5
WALLNUT_HEALTH = 30
WALLNUT_CRACKED1_HEALTH = 20
WALLNUT_CRACKED2_HEALTH = 10
WALLNUT_BOWLING_DAMAGE = 10
PRODUCE_SUN_INTERVAL = 7000
FLOWER_SUN_INTERVAL = 22000
SUN_LIVE_TIME = 7000
SUN_VALUE = 25
ICE_SLOW_TIME = 2000
FREEZE_TIME = 7500
ICETRAP = 'IceTrap'
CARD_SUNFLOWER = 'card_sunflower'
CARD_PEASHOOTER = 'card_peashooter'
CARD_SNOWPEASHOOTER = 'card_snowpea'
CARD_WALLNUT = 'card_wallnut'
CARD_CHERRYBOMB = 'card_cherrybomb'
CARD_THREEPEASHOOTER = 'card_threepeashooter'
CARD_REPEATERPEA = 'card_repeaterpea'
CARD_CHOMPER = 'card_chomper'
CARD_PUFFSHROOM = 'card_puffshroom'
CARD_POTATOMINE = 'card_potatomine'
CARD_SQUASH = 'card_squash'
CARD_SPIKEWEED = 'card_spikeweed'
CARD_JALAPENO = 'card_jalapeno'
CARD_SCAREDYSHROOM = 'card_scaredyshroom'
CARD_SUNSHROOM = 'card_sunshroom'
CARD_ICESHROOM = 'card_iceshroom'
CARD_HYPNOSHROOM = 'card_hypnoshroom'
CARD_REDWALLNUT = 'card_redwallnut'
BULLET_PEA = 'PeaNormal'
BULLET_PEA_ICE = 'PeaIce'
BULLET_MUSHROOM = 'BulletMushRoom'
BULLET_DAMAGE_NORMAL = 1
ZOMBIE_IMAGE_RECT = 'zombie_image_rect'
ZOMBIE_HEAD = 'ZombieHead'
NORMAL_ZOMBIE = 'Zombie'
CONEHEAD_ZOMBIE = 'ConeheadZombie'
BUCKETHEAD_ZOMBIE = 'BucketheadZombie'
FLAG_ZOMBIE = 'FlagZombie'
NEWSPAPER_ZOMBIE = 'NewspaperZombie'
BOOMDIE = 'BoomDie'
LOSTHEAD_HEALTH = 5
NORMAL_HEALTH = 10
FLAG_HEALTH = 15
CONEHEAD_HEALTH = 20
BUCKETHEAD_HEALTH = 30
NEWSPAPER_HEALTH = 15
ATTACK_INTERVAL = 1000
ZOMBIE_WALK_INTERVAL = 70
ZOMBIE_START_X = SCREEN_WIDTH + 50
IDLE = 'idle'
FLY = 'fly'
EXPLODE = 'explode'
ATTACK = 'attack'
ATTACKED = 'attacked'
DIGEST = 'digest'
WALK = 'walk'
DIE = 'die'
CRY = 'cry'
FREEZE = 'freeze'
SLEEP = 'sleep'
CHOOSE = 'choose'
PLAY = 'play'
BACKGROUND_DAY = 0
BACKGROUND_NIGHT = 1

state/main.py wires the state objects together, creates a Control instance, registers the menu, victory, lose, and level states, and starts the main game loop.

from . import tool
from . import constants as c
from .state import mainmenu, screen, level

def main():
    game = tool.Control()
    state_dict = {c.MAIN_MENU: mainmenu.Menu(),
                  c.GAME_VICTORY: screen.GameVictoryScreen(),
                  c.GAME_LOSE: screen.GameLoseScreen(),
                  c.LEVEL: level.Level()}
    game.setup_states(state_dict, c.MAIN_MENU)
    game.main()

The overall structure demonstrates a clean separation of concerns, making the game extensible and maintainable for further development or educational purposes.