19. 經典遊戲(四): Sprite引擎介紹與小精靈

15th鐵人賽

r4forth

2023-09-20 00:13:50

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Sprite 精靈圖介紹

精靈圖(Sprite)又叫做「拚合圖」，可將許多單一的小圖片合併成一張大圖，透過索引與座標來控制圖像的顯示。可減少檔案讀取時間，增加系統反應速度。精靈圖源於1974年街機興起，唯讀記憶體中的精靈圖被大量使用，增加遊戲畫面的可看性與顯示速度。

近年來網路技術興起，CSS 拼合圖(CSS Sprite)技術也借鏡早期精靈圖的核心，將需要分別顯示的多張圖片整合成單一大圖，利用CSS分別定位顯示各圖的技術，減少瀏覽器下載圖片的數量，提高網頁顯示速度。

玩學機內建的 Sprite 引擎

玩學機除了物聯網的應用外，另外一個強項就是拿來開發復古小遊戲。玩學機團隊中，就有當年開發紅白機遊戲的資深工程師。團隊為了要引導孩子「做中學、玩中學」的玩學精神，特地在系統內建了一張 Sprite 圖。程式教學的教師與學生，可利用這些素材，做出生動有趣的小遊戲，讓學習者了解當年製作遊戲的許多技巧，更能理解電腦圖學教科書中的許多理論知識。

因為 Sprite 圖形已經燒錄到系統中，我們是無法直接修改它。為了要知道裡面有什麼元件，我們先寫一個小程式來抓出裡面的排列規則。

wb.blitpal()
while True:
    for i in range(0, 80):
        wb.blitbuf()
        wb.blitimg(i*16, 0, 0, 128, 128)
        if wb.getkey() == 1:					    # 我們運用一個技巧，按住右邊黃鍵
            time.sleep(20)                      # 暫停20秒，可拿出手機拍攝記錄
        wb.blit()
        time.sleep(0.1)

透過擷取這些照片，我們可以推斷規則，這樣學員便可快速找出圖片的索引值，方便使用。幾個簡單的規則，整理如下:

英文數字符號規則
WiFiBoy Logo
小精靈遊戲素材
坦克大戰素材

其他還有許多圖案，有興趣的同學可以自行研究。

取出數字、符號與字元

內建的 Sprite 圖檔為 128X640 大小的圖形，裡面的數字、符號與字元元素是 8x8 的像素圖檔，128 / 8 = 16，640 / 8 = 80，每一個像素圖檔有索引值可以呼叫指定的圖形。

列出字型檔全部圖案X: 8 * 16 = 128，Y: 8 * 6 = 48 wb.blitimg(0, 8, 64, 128, 48) # 畫出圖型
印出大寫A wb.blitimg(65-32, 8, 64, 8, 8) # 畫出圖型
印白色WiFiBoy.org wb.blitimg(96, 8, 56, 64, 8)
印藍色WiFiBoy.org wb.blitimg(104, 8, 64, 64, 8)

wb.blitpal()							   # 啟動調色盤
for i in range(0,1024):					   # 啟動列印像素圖迴圈
    wb.blitbuf()						   # 清除記憶空間
    wb.blitimg(i, 8, 64, 8, 8)	           # 畫出圖型
    if wb.getkey() == 64:                  # 按下右上方 menu 綠色按鍵暫停 10 秒
        time.sleep(10)
    wb.blit()
    time.sleep(0.1)

印出 WiFiBoy 的 Logo

# 印出藍白商標圖
for i in range(0,2):						# 啟動列印像素圖迴圈
    wb.blitbuf()							# 清除記憶空間
    # 印白色WiFiBoy.org
    wb.blitimg(96, 8, 56, 64, 8)
    # 印藍色WiFiBoy.org
    wb.blitimg(104, 8, 64, 64, 8)
    wb.blit()
    time.sleep(0.1)

小精靈的素材

畫出小精靈地圖

wb.cls()
wb.blitbuf()
wb.blitimg(464, 20, 4, 120, 16) # 地圖上面一排，索引第 464 個圖案，起點(20,4)，長度120，原始圖案為16X16，取8x8 即為上半部
# 畫垂直邊界
for i in range(14):
    wb.blitimg(424, 131, 12+i*8) # 右邊界圖像
    wb.blitimg(421, 21, 12+i*8)  # 左邊界圖像

wb.blitimg(480, 20, 124, 120, 8) # 地圖最下面一排。
# 畫地圖中間兩個牆壁
wb.blitimg(400, 40, 52, 8, 32); wb.blitimg(400, 112, 52, 8, 32)
# 畫地圖上方兩個牆壁
wb.blitimg(401, 40, 28, 32, 8); wb.blitimg(401, 88, 28, 32, 8)
# 畫地圖上方兩個牆壁
wb.blitimg(401, 40, 100, 32, 8); wb.blitimg(401, 88, 100, 32, 8)
# 畫地圖最中間的方塊，鬼出現的基地
wb.blitimg(405, 64, 52, 32, 32);
# 畫櫻桃
wb.blitimg(368, 72, 56, 16, 16)
# 畫地圖中間的豆子
for i in range(13):
    for j in range(13):
        if bean[i+j*13]==1: wb.blitimg(417, 28+i*8, 16+j*8)
        elif bean[i+j*13]==2: wb.blitimg(418, 28+i*8, 16+j*8)
        elif bean[i+j*13]==3: wb.blitimg(368, 72, 84, 16, 16)

wb.blit() # blit all to refresh display

坦克大戰素材

PacBoy 特製版小精靈

感謝玩學運算科技公司提供底下的範例程式，讓我們可以了解如何在短短兩百九十行內寫完一個這麼有趣的小精靈遊戲。

# WiFiBoy OK:ESP32 Pacman Clone Game (BLITENGINE)
# Jan 3, 2020, by Peter Gabriel under CC-BY-4.0 license
# Modifiy By Daniel Teng 2023.09.18
import machine, time
try:
    if snd: snd.deinit()
except: pass

machine.Pin(17,3).value(1)
snd=machine.PWM(machine.Pin(25, 3))
snd.duty(0)

env1=[90,60,30,0,0,0,0,0]
env2=[90,60,30,20,15,10,5,0]
env3=[20,90,20,80,20,60,5,0]
env4=[90,20,90,20,10,20,10,0]

f=[round(110*2**(x/12)) for x in range(51)]

mel1=[22,13,0,0]
mel2=[30,32,34,36]
mel3=[30,32,38,0]
mel4=[16,22,28,0,26,0,28,0]
mel5=[39,0,51,0,46,0,43,0, 51,46,0,0,43,0,0,0,
      40,0,52,0,47,0,44,0,52,0,47,0,44,0,0,0,
      39,0,51,0,46,0,43,0, 51,46,0,0,43,0,0,0,
      44,44,0,45,0,45,46,0,47,0,47,48,49,0,51,51,0]
mel6=[40,0,42,0,44,0,45,0,47,0,49,0,51,0,0]
mel7=[40,41,0,0,0,0,0,40,0,0]

def play(dt, mel, env, shift): # melody engine
    for i in range(0, len(mel)):
        if (mel[i]!=0):
            snd.freq(f[mel[i]+shift])
            ei=0
        for j in range(0, 4):
            if (ei<8):snd.duty(env[ei])
            time.sleep(dt)
            ei=ei+1
            
def soundit(f):
    snd.freq(f)
    snd.duty(90)
    time.sleep(0.005)
    snd.duty(0)

cposx = [0,48,96,0,24,48,72,96,0,24,48,72,96,0,48,96]
cposy = [0,0,0,24,24,24,24,24,72,72,72,72,72,96,96,96]
cturn = [1,6,2,5,6,8,6,7,5,8,6,8,7,3,8,4]
dirx=[0, 2, 0, -2] # up,right,down,left
diry=[-2, 0, 2, 0]
level = 1; life = 5
score = pwrcount = kbr = pani = pflp = 0

def reset_ghost():
    global gx, gy, gdx, gdy, gtype, pwrcount
    gx = [0, 96, 24, 72, 48, 0, 96, 96, 48]
    gy = [0, 24, 48, 48, 24, 96, 96, 0, 0]
    gdx = [1, 0, 0, 0, 1, 0, -1, -1, 0]
    gdy = [0, -1, -1, 1, 0, -1, 0, 0, 1]
    gtype = [0,0,0,0,0,0,0,0,0]
    pwrcount=0
    
def reset_game():
    global bean, bcount, px, py, dx, dy, pwrcount
    bean = [2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2,
            1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1,
            1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1,
            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
            1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,
            1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,
            1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,
            1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,
            1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1,
            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
            1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1,
            1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1,
            2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2]
    px = 48; py = 72
    bcount = dx = dy = 0
    pwrcount=0
    reset_ghost()
    play(0.012, mel5, env1, -24)
# 繪製場景
def draw_scene():
    wb.blitbuf()
    wb.blitimg(464, 20, 4, 120, 8)
    for i in range(14): wb.blitimg(424, 131, 12+i*8); wb.blitimg(421, 21, 12+i*8)
    wb.blitimg(480, 20, 124, 120, 8)
    for i in range(13):
        for j in range(13):
            if bean[i+j*13]==1: wb.blitimg(417, 28+i*8, 16+j*8)
            elif bean[i+j*13]==2: wb.blitimg(418, 28+i*8, 16+j*8)
            elif bean[i+j*13]==3: wb.blitimg(368, 72, 84, 16, 16)
    wb.blitimg(400, 40, 52, 8, 32); wb.blitimg(400, 112, 52, 8, 32)
    wb.blitimg(401, 40, 28, 32, 8); wb.blitimg(401, 88, 28, 32, 8)
    wb.blitimg(401, 40, 100, 32, 8); wb.blitimg(401, 88, 100, 32, 8)
    wb.blitimg(405, 64, 52, 32, 32); wb.blitimg(368, 72, 56, 16, 16)
    
def draw_score():
    wb.blitstr("SCORE "+str(score)+" Lv"+str(level),20,0)
    wb.blitstr("x"+str(life),71,72);
    wb.blit() # blit all to refresh display
    
def caught():
    global life, level, score, px, py, dx, dy, bean
    dx=dy=0
    for i in range(8):
        draw_scene()
        wb.blitimg(304+i*2, px+24, py+12, 16, 16)
        draw_score()
        for j in range(8): soundit(90*(9-i)+j*50)
    life -= 1
    draw_scene()
    if life==0: wb.blitstr("GAME OVER!", 40,24)
    else: wb.blitstr("CAUGHT!!", 48,24)
    wb.blitstr("PRESS A KEY", 37,96)
    draw_score()  
    if life==0: life=5; score=0; level=1; reset_game()
    else: px = 48; py = 72; dx = dy = 0
    while wb.getkey()!=0: pass
    while wb.getkey()==0: pass
    reset_ghost()
    if bean[123]==3: bean[123]=0 #clean 1up bonus

def eat_ghost(n):
    global score, gx, gy, gdx, gdy, gtype
    score+=100
    gx[n]=gy[n]=48
    gdx[n]=0; gdy[n]=-1
    gtype[n]=0
    play(0.005, mel6, env2, -24)

def ghost_turn2(n, a, b):
    r = wb.rand(2)
    if r==1: gdx[n]=dirx[a]; gdy[n]=diry[a]
    else: gdx[n]=dirx[b]; gdy[n]=diry[b]

def ghost_turn3(n, a, b, c):
    r = wb.rand(3)
    if r==1: gdx[n]=dirx[a]; gdy[n]=diry[a]
    elif r==2: gdx[n]=dirx[b]; gdy[n]=diry[b]
    else: gdx[n]=dirx[c]; gdy[n]=diry[c]

def ghost_go():
    global gx, gy, gdx, gdy
    for i in range(level):
        if gx[i]==px and gy[i]==py: 
            if gtype[i]==1: eat_ghost(i)
            else: caught()
            return
        gx[i] += gdx[i]
        gy[i] += gdy[i]
        if gx[i]==px and gy[i]==py: 
            if gtype[i]==1: eat_ghost(i)
            else: caught()
            return
        if (gx[i]%8!=0) and (gy[i]%8!=0): return
        for j in range(16):
            if (gx[i]==cposx[j] and gy[i]==cposy[j]):
                if cturn[j]==1: ghost_turn2(i, 1, 2)
                elif cturn[j]==2: ghost_turn2(i, 2, 3)
                elif cturn[j]==4: ghost_turn2(i, 0, 3)
                elif cturn[j]==3: ghost_turn2(i, 0, 1)
                elif cturn[j]==5: ghost_turn3(i, 0, 1, 2)
                elif cturn[j]==6: ghost_turn3(i, 1, 2, 3)
                elif cturn[j]==7: ghost_turn3(i, 0, 2, 3)
                elif cturn[j]==8: ghost_turn3(i, 0, 1, 3)
    
def check_input():
    global px, py, dx, dy, bcount, score, level, pwrcount, life
    px += dx
    py += dy
    if (px%8!=0) and (py%8!=0): return
    if pwrcount>0: soundit(200)
    pos = int(px/8)+int(py/8)*13
    if bean[pos] == 1: 
        bean[pos]=0 
        score += 10
        if pwrcount>0: play(0.001, mel3, env3, 0)
        else: soundit(300) 
        bcount += 1
        if bcount==80: # level done
            dx=dy=0
            draw_scene()
            pac_go()
            wb.blitstr("CLEAN!!", 56,40)
            wb.blitstr("NEXT LEVEL..", 36,112)
            draw_score()
            level += 1
            if level > 9: level=9                
            while wb.getkey()!=0: pass
            while wb.getkey()==0: pass
            reset_game()
            return
        elif bcount==60: #60-bean 1up
            if bean[0]+bean[12]+bean[156]+bean[168]>5: 
                bean[123]=3
                play(0.005, mel1, env1, 0)
    elif bean[pos] == 2: 
        bean[pos]=0 # power bean
        play(0.005, mel2, env1, 0)
        pwrcount=100
        for i in range(level): gtype[i]=1
    elif bean[pos] == 3:
        life += 1; bean[pos] = 0
        if life>9: life=9
        play(0.005, mel7, env2, -2)   
    for i in range(16):
        if (px==cposx[i] and py==cposy[i]):
            kb = wb.getkey()
            if cturn[i]==1: #corner 0
                if kb&4==4: dx=2; dy=0
                elif kb&16==16: dx=0; dy=2
                else: dx=0; dy=0
            elif cturn[i]==2:
                if kb&8==8: dx=-2; dy=0
                elif kb&16==16: dx=0; dy=2
                else: dx=0; dy=0
            elif cturn[i]==4:
                if kb&32==32: dx=0; dy=-2
                elif kb&8==8: dx=-2; dy=0
                else: dx=0; dy=0
            elif cturn[i]==3:
                if kb&32==32: dx=0; dy=-2
                elif kb&4==4: dx=2; dy=0
                else: dx=0; dy=0
            elif cturn[i]==5:
                if kb&32==32: dx=0; dy=-2
                elif kb&16==16: dx=0; dy=2
                elif kb&4==4: dx=2; dy=0
                elif dy==0: dx=0
            elif cturn[i]==6:
                if kb&16==16: dx=0; dy=2
                elif kb&8==8: dx=-2; dy=0
                elif kb&4==4: dx=2; dy=0
                elif dx==0: dy=0    
            elif cturn[i]==7:
                if kb&32==32: dx=0; dy=-2
                elif kb&16==16: dx=0; dy=2
                elif kb&8==8: dx=-2; dy=0    
                elif dy==0: dx=0
            elif cturn[i]==8:
                if kb&32==32: dx=0; dy=-2
                elif kb&8==8: dx=-2; dy=0
                elif kb&4==4: dx=2; dy=0 
                elif dx==0: dy=0
            return
    kb = wb.getkey()
    if kb&32==32 and dy==2: dy=-2
    elif kb&16==16 and dy==-2: dy=2
    elif kb&8==8 and dx==2: dx=-2
    elif kb&4==4 and dx==-2: dx=2

def pac_go():
    global pani, pflp, pwrcount
    pani+=1
    if pani%4==0: pflp = 1-pflp
    if pwrcount>0:
        pwrcount -= 1
        if pwrcount==0:
            for i in range(level): gtype[i]=0
    #ghost
    for i in range(level):
        if gtype[i]==1: wb.blitimg(376+pflp*2, gx[i]+24, gy[i]+12, 16,16)
        else: wb.blitimg(336+(i%4)*4+pflp*2, gx[i]+24, gy[i]+12, 16,16)
    #pacman        
    if dx>0: wb.blitimg(272+pflp*2, px+24, py+12, 16, 16)
    elif dx<0: wb.blitimg(280+pflp*2, px+24, py+12, 16, 16)
    elif dy<0: wb.blitimg(284+pflp*2, px+24, py+12, 16, 16)
    elif dy>0: wb.blitimg(276+pflp*2, px+24, py+12, 16, 16)
    else: wb.blitimg(304, px+24, py+12, 16, 16)
        
wb.blitbuf()
wb.blitimg(272, 41, 40, 16, 16)
wb.blitimg(336, 61, 40, 16, 16)
wb.blitimg(340, 81, 40, 16, 16)
wb.blitimg(344, 101, 40, 16, 16)
wb.blitstr("PacBoy Demo 2023", 16, 70)
wb.blit()
reset_game()

while True:
    draw_scene()
    check_input()
    ghost_go()
    pac_go()
    draw_score()

堅持到現在真是不簡單，明天我們將要介紹「45行寫出小蜜蜂遊戲」。