笔记（9）

编程需要两样东西：思路和工具。Python的特点就是很直白，也很贴近生活，即使没系统学过这种语言，也能从它的逻辑中读懂大概意思。因为这门语言更贴近人的想法，而不仅仅是冰冷的机器语言，所以更容易实现个体的想法。下面是个简单的塔防游戏例子：1、防守方，敌人，子弹，时间条，血条；2、运动轨迹、子弹轨迹；3、逻辑线条、算法计算；4、优化，包括统计结果、背景音乐、图片美观、用户体验。

其中一些代码是固定套路，可以移植，重复使用。如果从本质看塔防游戏（比如“保卫萝卜”）就是个你来我射的拉锯战，就是射击，要实现的包括：位移和碰撞消减，既然是游戏，包括人机互动（按键和鼠标的实现功能，很方便地体现在pygame模块包中）。

例子来源：http://blog.jobbole.com/46308/

感兴趣的最好看原版，略作修改，Python3版本可以实现，效果如下图：

 

# 1 - Import library
import pygame
from pygame.locals import *
import math
import random

# 2 - Initialize the game
pygame.init()
width, height = 640, 480   # 设置游戏屏幕大小
screen = pygame.display.set_mode((width, height))
keys = [False, False, False, False]  # 方向键和玩家初始位置的设置，当游戏进行时，玩家位置将和兔子重合（控制兔子位置）
playerpos = [100, 100]
acc = [0, 0]
arrows = []
badtimer = 100
badtimer1 = 0
badguys = [[640, 100]]
healthvalue = 194
pygame.mixer.init()

# 3 - Load image 加载图片和背景音乐
player = pygame.image.load("resources/images/dude.png")
grass = pygame.image.load("resources/images/grass.png")
castle = pygame.image.load("resources/images/castle.png")
arrow = pygame.image.load("resources/images/bullet.png")
badguyimg1 = pygame.image.load("resources/images/badguy.png")
badguyimg = badguyimg1
healthbar = pygame.image.load("resources/images/healthbar.png")
health = pygame.image.load("resources/images/health.png")
gameover = pygame.image.load("resources/images/gameover.png")
youwin = pygame.image.load("resources/images/youwin.png")
# 3.1 - Load audio
hit = pygame.mixer.Sound("resources/audio/explode.wav")
enemy = pygame.mixer.Sound("resources/audio/enemy.wav")
shoot = pygame.mixer.Sound("resources/audio/shoot.wav")
hit.set_volume(0.05)
enemy.set_volume(0.05)
shoot.set_volume(0.05)
pygame.mixer.music.load('resources/audio/moonlight.wav')  # pygame.mixer.music.load 这一行加载游戏的背景音乐然后下一行让背景音乐一直不停的播放
pygame.mixer.music.play(-1, 0.0)
pygame.mixer.music.set_volume(0.25)  # 设置音量
#xx = list(range(width//grass.get_width()+1))
#yy = list(range(height//grass.get_height()+1))

# 4 - keep looping through
running = 1
exitcode = 0
while running:   # running变量会跟踪游戏是否结束
    badtimer -= 1
    # 5 - clear the screen before drawing it again
    screen.fill(0)
    # 6 - draw the player on the screen at X:100, Y:100
 #   for x in xx:
 #       for y in yy:
    for x in range(width//grass.get_width()+1):   # get 图片的宽和高
        for y in range(height//grass.get_height()+1):
            screen.blit(grass, (x*100, y*100))  # 双层循环嵌套，确保背景图片完全覆盖
    screen.blit(castle, (0, 30))   # 该函数表示在屏幕的特定位置安放特定图片
    screen.blit(castle, (0, 135))
    screen.blit(castle, (0, 240))
    screen.blit(castle, (0, 345))
    # 6.1 - Set player position and rotation
    position = pygame.mouse.get_pos()
    angle = math.atan2(position[1]-(playerpos[1]+32), position[0]-(playerpos[0]+26))  # atan2（y,x）[1]是y维；[0]是x维，因为兔子不是一个质点，参考位置不同就有32和26的微调
    playerrot = pygame.transform.rotate(player, 360-angle*57.29)  # 设置兔子图形转向，所以下面的playerrot既包含图形又包含转向的性质，同时需要把弧度转为角度
    playerpos1 = (playerpos[0]-playerrot.get_rect().width/2, playerpos[1]-playerrot.get_rect().height/2)
    screen.blit(playerrot, playerpos1)  # 兔子位置移动包括按键（直上直下）和鼠标操纵（转向）
    # 6.2 - Draw arrows  if表达式是检查箭头是否超出了屏幕范围，如果超出，就删除这个箭头。第二个for表达式是循环来把箭头根据相应的旋转画出来。
    for bullet in arrows:
        index = 0
        velx = math.cos(bullet[0])*10
        vely = math.sin(bullet[0])*10
        bullet[1] += velx
        bullet[2] += vely
        if bullet[1] < -64 or bullet[1] > 640 or bullet[2] < -64 or bullet[2] > 480:
            arrows.pop(index)
        index += 1
        for projectile in arrows:
            arrow1 = pygame.transform.rotate(arrow, 360-projectile[0]*57.29)
            screen.blit(arrow1, (projectile[1], projectile[2]))
    # 6.3 - Draw badgers
    if badtimer == 0:
        badguys.append([640, random.randint(50, 430)])
        badtimer = 100-(badtimer1*2)
        if badtimer1 >= 35:
            badtimer1 = 35
        else:
            badtimer1 += 5
    index = 0
    for badguy in badguys:
        if badguy[0] < -64:
            badguys.pop(index)
        badguy[0] -= 7
        # 6.3.1 - Attack castle  如果獾的x坐标离右边小于64，就删除坏蛋并且减少游戏里的健康值，减少的大小为5至20里的一个随机数。
        badrect=pygame.Rect(badguyimg.get_rect())
        badrect.top=badguy[1]
        badrect.left=badguy[0]
        if badrect.left<64:
            hit.play()
            healthvalue -= random.randint(5,20)
            badguys.pop(index)
        #6.3.2 - Check for collisions 
        index1=0
        for bullet in arrows:
            bullrect=pygame.Rect(arrow.get_rect())
            bullrect.left=bullet[1]
            bullrect.top=bullet[2]
            if badrect.colliderect(bullrect):  # 查看子弹和敌人是否碰撞
                enemy.play()
                acc[0]+=1   # 统计精确度，碰撞加一
                badguys.pop(index)
                arrows.pop(index1)  # 碰撞则消除两者
            index1+=1
        # 6.3.3 - Next bad guy
        index+=1
    for badguy in badguys:
        screen.blit(badguyimg, badguy)
    # 6.4 - Draw clock
    font = pygame.font.Font(None, 24)
    survivedtext = font.render(str((90000-pygame.time.get_ticks())//60000)+":"+str((90000-pygame.time.get_ticks())//1000%60).zfill(2), True, (0,0,0))
    textRect = survivedtext.get_rect()
    textRect.topright = [635, 5]
    screen.blit(survivedtext, textRect)
    # 6.5 - Draw health bar
    screen.blit(healthbar, (5,5))
    for health1 in range(healthvalue):
        screen.blit(health, (health1+8,8))
    # 7 - update the screen
    pygame.display.flip()
    # 8 - loop through the events
    for event in pygame.event.get():
        # check if the event is the X button 
        if event.type == pygame.QUIT:
            # if it is quit the game
            pygame.quit()
            exit(0)
        if event.type == pygame.KEYDOWN:  # 这是最有趣的地方——人机互动，你检查是否有一个键被按下或放开。然后，检查是哪一个键被按下或放开了，如果被按下或放开的键是你使用的，你就更新记录按键的变量。
            if event.key==K_w:
                keys[0]=True
            elif event.key==K_a:
                keys[1]=True
            elif event.key==K_s:
                keys[2]=True
            elif event.key==K_d:
                keys[3]=True
        if event.type == pygame.KEYUP:
            if event.key==pygame.K_w:
                keys[0]=False
            elif event.key==pygame.K_a:
                keys[1]=False
            elif event.key==pygame.K_s:
                keys[2]=False
            elif event.key==pygame.K_d:
                keys[3]=False
        if event.type==pygame.MOUSEBUTTONDOWN:  # 相应的鼠标按键检查，确定是否射击和射击初始位置及箭头（图形）旋转角度
            shoot.play()
            position=pygame.mouse.get_pos()
            acc[1]+=1
            arrows.append([math.atan2(position[1]-(playerpos1[1]+32),position[0]-(playerpos1[0]+26)),playerpos1[0]+32,playerpos1[1]+32])
                
    # 9 - Move player
    if keys[0]:   # 0、1、2、3对应W、A、S、D，对应位置以5个单位的移动变化
        playerpos[1]-=5
    elif keys[2]:
        playerpos[1]+=5
    if keys[1]:
        playerpos[0]-=5
    elif keys[3]:
        playerpos[0]+=5

    #10 - Win/Lose check   第一个if表达式是检查是否时间到了。第二个是检查城堡是否被摧毁了。第三个计算你的精准度。之后，一个if表达式是检查你是赢了还是输了，然后显示出相应的图片。
    if pygame.time.get_ticks()>=90000:
        running=0
        exitcode=1
    if healthvalue<=0:
        running=0
        exitcode=0
    if acc[1]!=0:
        accuracy=acc[0]*1.0/acc[1]*100
    else:
        accuracy=0
# 11 - Win/lose display        
if exitcode==0:
    pygame.font.init()
    font = pygame.font.Font(None, 24)
    text = font.render("Accuracy: "+str(accuracy)+"%", True, (255,0,0))
    textRect = text.get_rect()
    textRect.centerx = screen.get_rect().centerx
    textRect.centery = screen.get_rect().centery+24
    screen.blit(gameover, (0,0))
    screen.blit(text, textRect)
else:
    pygame.font.init()
    font = pygame.font.Font(None, 24)
    text = font.render("Accuracy: "+str(accuracy)+"%", True, (0,255,0))
    textRect = text.get_rect()
    textRect.centerx = screen.get_rect().centerx
    textRect.centery = screen.get_rect().centery+24
    screen.blit(youwin, (0,0))
    screen.blit(text, textRect)
while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            exit(0)
    pygame.display.flip()