在一个虚拟鱼缸里观看你自己的虚拟鱼，里面有气泡器和海藻植物。每次你运行这个程序，它会用不同的鱼类型和颜色随机生成鱼。休息一下，享受这个软件水族馆的平静安详，或者尝试在一些虚拟鲨鱼中编程来恐吓它的居民！您不能从 IDE 或编辑器中运行该程序。该程序使用bext模块，必须从命令提示符或终端运行才能正确显示。关于bext模块的更多信息可以在pypi.org/project/bext找到。
图 27-1 显示了运行fishtank.py时的输出。
:鱼缸程序的输出，有几条鱼、海藻和泡泡
现代图形程序通常通过擦除整个窗口并每秒重绘 30 或 60 次来生成动画。这给了他们每秒 30 或 60 帧（FPS）的帧速率。FPS 越高，动画运动就越流畅。
绘制到终端窗口要慢得多。如果我们擦除整个终端窗口，用bext模块重新绘制它的内容，我们通常只能得到大约 3 或 4 FPS。这将导致窗口明显闪烁。
我们可以通过只在终端窗口发生变化的部分绘制字符来加快速度。鱼缸程序的大部分输出是空白空间，所以为了让元素移动，clearAquarium()只需要在鱼、海藻和泡泡当前所在的地方画出' '个空格字符。这增加了我们的帧速率，减少了闪烁，并使鱼缸动画更加令人愉快。
"""Fish Tank, by Al Sweigart email@protected
A peaceful animation of a fish tank. Press Ctrl-C to stop.
Similar to ASCIIQuarium or @EmojiAquarium, but mine is based on an
older ASCII fish tank program for DOS.
https://robobunny.com/projects/asciiquarium/html/
https://twitter.com/EmojiAquarium
This code is available at https://nostarch.com/big-book-small-python-programming
Tags: extra-large, artistic, bext"""
import random, sys, time
try:
import bext
except ImportError:
print('This program requires the bext module, which you')
print('can install by following the instructions at')
print('https://pypi.org/project/Bext/')
sys.exit()
# Set up the constants:
WIDTH, HEIGHT = bext.size()
# We can't print to the last column on Windows without it adding a
# newline automatically, so reduce the width by one:
WIDTH -= 1
NUM_KELP = 2 # (!) Try changing this to 10.
NUM_FISH = 10 # (!) Try changing this to 2 or 100.
NUM_BUBBLERS = 1 # (!) Try changing this to 0 or 10.
FRAMES_PER_SECOND = 4 # (!) Try changing this number to 1 or 60.
# (!) Try changing the constants to create a fish tank with only kelp,
# or only bubblers.
# NOTE: Every string in a fish dictionary should be the same length.
FISH_TYPES = [
{'right': ['><>'], 'left': ['<><']},
{'right': ['>||>'], 'left': ['<||<']},
{'right': ['>))>'], 'left': ['<[[<']},
{'right': ['>||o', '>||.'], 'left': ['o||<', '.||<']},
{'right': ['>))o', '>)).'], 'left': ['o[[<', '.[[<']},
{'right': ['>-==>'], 'left': ['<==-<']},
{'right': [r'>\\>'], 'left': ['<//<']},
{'right': ['><)))*>'], 'left': ['<*(((><']},
{'right': ['}-[[[*>'], 'left': ['<*]]]-{']},
{'right': [']-<)))b>'], 'left': ['<d(((>-[']},
{'right': ['><XXX*>'], 'left': ['<*XXX><']},
{'right': ['_.-._.-^=>', '.-._.-.^=>',
'-._.-._^=>', '._.-._.^=>'],
'left': ['<=^-._.-._', '<=^.-._.-.',
'<=^_.-._.-', '<=^._.-._.']},
] # (!) Try adding your own fish to FISH_TYPES.
LONGEST_FISH_LENGTH = 10 # Longest single string in FISH_TYPES.
# The x and y positions where a fish runs into the edge of the screen:
LEFT_EDGE = 0
RIGHT_EDGE = WIDTH - 1 - LONGEST_FISH_LENGTH
TOP_EDGE = 0
BOTTOM_EDGE = HEIGHT - 2
def main():
global FISHES, BUBBLERS, BUBBLES, KELPS, STEP
bext.bg('black')
bext.clear()
# Generate the global variables:
FISHES = []
for i in range(NUM_FISH):
FISHES.append(generateFish())
# NOTE: Bubbles are drawn, but not the bubblers themselves.
BUBBLERS = []
for i in range(NUM_BUBBLERS):
# Each bubbler starts at a random position.
BUBBLERS.append(random.randint(LEFT_EDGE, RIGHT_EDGE))
BUBBLES = []
KELPS = []
for i in range(NUM_KELP):
kelpx = random.randint(LEFT_EDGE, RIGHT_EDGE)
kelp = {'x': kelpx, 'segments': []}
# Generate each segment of the kelp:
for i in range(random.randint(6, HEIGHT - 1)):
kelp['segments'].append(random.choice(['(', ')']))
KELPS.append(kelp)
# Run the simulation:
STEP = 1
while True:
simulateAquarium()
drawAquarium()
time.sleep(1 / FRAMES_PER_SECOND)
clearAquarium()
STEP += 1
def getRandomColor():
"""Return a string of a random color."""
return random.choice(('black', 'red', 'green', 'yellow', 'blue',
'purple', 'cyan', 'white'))
def generateFish():
"""Return a dictionary that represents a fish."""
fishType = random.choice(FISH_TYPES)
# Set up colors for each character in the fish text:
colorPattern = random.choice(('random', 'head-tail', 'single'))
fishLength = len(fishType['right'][0])
if colorPattern == 'random': # All parts are randomly colored.
colors = []
for i in range(fishLength):
colors.append(getRandomColor())
if colorPattern == 'single' or colorPattern == 'head-tail':
colors = [getRandomColor()] * fishLength # All the same color.
if colorPattern == 'head-tail': # Head/tail different from body.
headTailColor = getRandomColor()
colors[0] = headTailColor # Set head color.
colors[-1] = headTailColor # Set tail color.
# Set up the rest of fish data structure:
fish = {'right': fishType['right'],
'left': fishType['left'],
'colors': colors,
'hSpeed': random.randint(1, 6),
'vSpeed': random.randint(5, 15),
'timeToHDirChange': random.randint(10, 60),
'timeToVDirChange': random.randint(2, 20),
'goingRight': random.choice([True, False]),
'goingDown': random.choice([True, False])}
# 'x' is always the leftmost side of the fish body:
fish['x'] = random.randint(0, WIDTH - 1 - LONGEST_FISH_LENGTH)
fish['y'] = random.randint(0, HEIGHT - 2)
return fish
def simulateAquarium():
"""Simulate the movements in the aquarium for one step."""
global FISHES, BUBBLERS, BUBBLES, KELP, STEP
# Simulate the fish for one step:
for fish in FISHES:
# Move the fish horizontally:
if STEP % fish['hSpeed'] == 0:
if fish['goingRight']:
if fish['x'] != RIGHT_EDGE:
fish['x'] += 1 # Move the fish right.
else:
fish['goingRight'] = False # Turn the fish around.
fish['colors'].reverse() # Turn the colors around.
else:
if fish['x'] != LEFT_EDGE:
fish['x'] -= 1 # Move the fish left.
else:
fish['goingRight'] = True # Turn the fish around.
fish['colors'].reverse() # Turn the colors around.
# Fish can randomly change their horizontal direction:
fish['timeToHDirChange'] -= 1
if fish['timeToHDirChange'] == 0:
fish['timeToHDirChange'] = random.randint(10, 60)
# Turn the fish around:
fish['goingRight'] = not fish['goingRight']
# Move the fish vertically:
if STEP % fish['vSpeed'] == 0:
if fish['goingDown']:
if fish['y'] != BOTTOM_EDGE:
fish['y'] += 1 # Move the fish down.
else:
fish['goingDown'] = False # Turn the fish around.
else:
if fish['y'] != TOP_EDGE:
fish['y'] -= 1 # Move the fish up.
else:
fish['goingDown'] = True # Turn the fish around.
# Fish can randomly change their vertical direction:
fish['timeToVDirChange'] -= 1
if fish['timeToVDirChange'] == 0:
fish['timeToVDirChange'] = random.randint(2, 20)
# Turn the fish around:
fish['goingDown'] = not fish['goingDown']
# Generate bubbles from bubblers:
for bubbler in BUBBLERS:
# There is a 1 in 5 chance of making a bubble:
if random.randint(1, 5) == 1:
BUBBLES.append({'x': bubbler, 'y': HEIGHT - 2})
# Move the bubbles:
for bubble in BUBBLES:
diceRoll = random.randint(1, 6)
if (diceRoll == 1) and (bubble['x'] != LEFT_EDGE):
bubble['x'] -= 1 # Bubble goes left.
elif (diceRoll == 2) and (bubble['x'] != RIGHT_EDGE):
bubble['x'] += 1 # Bubble goes right.
bubble['y'] -= 1 # The bubble always goes up.
# Iterate over BUBBLES in reverse because I'm deleting from BUBBLES
# while iterating over it.
for i in range(len(BUBBLES) - 1, -1, -1):
if BUBBLES[i]['y'] == TOP_EDGE: # Delete bubbles that reach the top.
del BUBBLES[i]
# Simulate the kelp waving for one step:
for kelp in KELPS:
for i, kelpSegment in enumerate(kelp['segments']):
# 1 in 20 chance to change waving:
if random.randint(1, 20) == 1:
if kelpSegment == '(':
kelp['segments'][i] = ')'
elif kelpSegment == ')':
kelp['segments'][i] = '('
def drawAquarium():
"""Draw the aquarium on the screen."""
global FISHES, BUBBLERS, BUBBLES, KELP, STEP
# Draw quit message.
bext.fg('white')
bext.goto(0, 0)
print('Fish Tank, by Al Sweigart Ctrl-C to quit.', end='')
# Draw the bubbles:
bext.fg('white')
for bubble in BUBBLES:
bext.goto(bubble['x'], bubble['y'])
print(random.choice(('o', 'O')), end='')
# Draw the fish:
for fish in FISHES:
bext.goto(fish['x'], fish['y'])
# Get the correct right- or left-facing fish text.
if fish['goingRight']:
fishText = fish['right'][STEP % len(fish['right'])]
else:
fishText = fish['left'][STEP % len(fish['left'])]
# Draw each character of the fish text in the right color.
for i, fishPart in enumerate(fishText):
bext.fg(fish['colors'][i])
print(fishPart, end='')
# Draw the kelp:
bext.fg('green')
for kelp in KELPS:
for i, kelpSegment in enumerate(kelp['segments']):
if kelpSegment == '(':
bext.goto(kelp['x'], BOTTOM_EDGE - i)
elif kelpSegment == ')':
bext.goto(kelp['x'] + 1, BOTTOM_EDGE - i)
print(kelpSegment, end='')
# Draw the sand on the bottom:
bext.fg('yellow')
bext.goto(0, HEIGHT - 1)
print(chr(9617) * (WIDTH - 1), end='') # Draws '░' characters.
sys.stdout.flush() # (Required for bext-using programs.)
def clearAquarium():
"""Draw empty spaces over everything on the screen."""
global FISHES, BUBBLERS, BUBBLES, KELP
# Draw the bubbles:
for bubble in BUBBLES:
bext.goto(bubble['x'], bubble['y'])
print(' ', end='')
# Draw the fish:
for fish in FISHES:
bext.goto(fish['x'], fish['y'])
# Draw each character of the fish text in the right color.
print(' ' * len(fish['left'][0]), end='')
# Draw the kelp:
for kelp in KELPS:
for i, kelpSegment in enumerate(kelp['segments']):
bext.goto(kelp['x'], HEIGHT - 2 - i)
print(' ', end='')
sys.stdout.flush() # (Required for bext-using programs.)
# If this program was run (instead of imported), run the game:
if __name__ == '__main__':
try:
main()
except KeyboardInterrupt:
sys.exit() # When Ctrl-C is pressed, end the program. 在输入源代码并运行几次之后，尝试对其进行实验性的修改。标有(!)的注释对你可以做的小改变有建议。你也可以自己想办法做到以下几点：
- 加上在沙质海底移动的螃蟹。
- 添加一个随机出现在沙底的 ASCII 艺术画城堡。
- 让鱼在短时间内随机提高速度。
试着找出下列问题的答案。尝试对代码进行一些修改，然后重新运行程序，看看这些修改有什么影响。
- 如果把 51 行的
LONGEST_FISH_LENGTH = 10改成LONGEST_FISH_LENGTH = 50会怎么样？ - 如果把 121 行的
'right': fishType['right']改成'right': fishType['left']会怎么样？ - 如果把 249 行的
bext.fg('green')改成bext.fg('red')会怎么样？ - 如果删除或注释掉第 92 行的
clearAquarium()会发生什么？ - 如果把 245 行的
bext.fg(fish['colors'][i])改成bext.fg('random')会怎么样？ - 如果把 161 行的
random.randint(10, 60)改成1会怎么样？