Question

我一直试图制作一个递归的矩形，我想让每次重复时矩形都向前移动，这样当它进入一个无限的矩形时它会产生一个动作。我试图在每次递归时使尺寸变大但失败，因为它不会递归或什么都不会出现。任何提示或如何做到这一点将不胜感激。我从pygamearcade实现了这个示例。我希望得到这样的感觉，因为一个人进入矩形，并且可以实现，因为每次经历重复时矩形变大。所以任何提示或如何做到这一点都很好。谢谢

import pygame

# Colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)


def recursive_draw(x, y, width, height):
    """ Recursive rectangle function. """
    pygame.draw.rect(screen, WHITE,
                 [x, y, width, height],
                 1)
speed = [10,0]

# Is the rectangle wide enough to draw again?
while (width > 14):
    # Scale down
                    x += width * .1
                    y += height * .1
                    width *= .8
                    height *= .8

    # Recursively draw again
                    recursive_draw(x, y, width, height)

pygame.init()
#rectanglelist = [big()] 
# Set the height and width of the screen
size = [700, 500]
screen = pygame.display.set_mode(size)

pygame.display.set_caption("My Game")

# Loop until the user clicks the close button.
done = False

# Used to manage how fast the screen updates
clock = pygame.time.Clock()

# -------- Main Program Loop -----------
while not done:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

    # Set the screen background
    screen.fill(BLACK)

    # ALL CODE TO DRAW SHOULD GO BELOW THIS COMMENT
    recursive_draw(0, 0, 700, 500)
    # ALL CODE TO DRAW SHOULD GO ABOVE THIS COMMENT

    # Go ahead and update the screen with what we've drawn.
    pygame.display.flip()

    # Limit to 60 frames per second
    clock.tick(60)

# Be IDLE friendly. If you forget this line, the program will 'hang'
# on exit.
pygame.quit()

Answer 1

问题是你的 recursive_draw() 函数实际上不是递归函数，因为递归函数是有条件地调用自身的函数< /强>：

每个设计合理的递归函数必须至少一个基本案例 [A]并且必须将问题重新定义为子问题才能实现基础案例[B]。

def countdown(n): if n < 1: print "Lift Off" #[A] else: print n countdown(n - 1) #[B]

您可以为您的代码做些什么：

首先修复代码的缩进。

其次，用'if'语句替换你的while循环 这是重要的部分或递归：该函数调用自身，除非某个条件不再为真（在您的情况下为width > 14）。有关详细信息，请参阅SO上的How can I build a recursive function in python?或Recursion function in python。

更新后的功能（来自http://www.balloonbuilding.com/的代码 Paul Vincent Craven ）：

def recursive_draw(x, y, width, height): """ Recursive rectangle function. """ pygame.draw.rect(screen, BLACK, (x, y, width, height), 1) # Is the rectangle wide enough to draw again? if(width > 14): # Scale down x += width * .1 y += height * .1 width *= .8 height *= .8 # Recursively draw again recursive_draw(x, y, width, height)

我希望这会有所帮助：）

编辑：

更新后的计划：

import pygame # Colors BLUE = (55, 155, 255) WHITE = (255, 255, 255) def recursive_draw(x, y, width, height): """ Recursive rectangle function. """ pygame.draw.rect(screen, WHITE, (x, y, width, height), 2) # Is the rectangle wide enough to draw again? if(width > 14): # Scale down x += width * .1 y += height * .1 width *= .8 height *= .8 # Recursively draw again recursive_draw(x, y, width, height) speed = [10,0] pygame.init() #rectanglelist = [big()] # Set the height and width of the screen size = [700, 500] screen = pygame.display.set_mode(size) pygame.display.set_caption("My Game") # Loop until the user clicks the close button. done = False # Used to manage how fast the screen updates clock = pygame.time.Clock() # -------- Main Program Loop ----------- while not done: for event in pygame.event.get(): if event.type == pygame.QUIT: done = True # Set the screen background screen.fill(BLUE) # ALL CODE TO DRAW SHOULD GO BELOW THIS COMMENT recursive_draw(0, 0, 700, 500) # ALL CODE TO DRAW SHOULD GO ABOVE THIS COMMENT # Go ahead and update the screen with what we've drawn. pygame.display.flip() # Limit to 60 frames per second clock.tick(60) # Be IDLE friendly. If you forget this line, the program will 'hang' # on exit. pygame.quit()

截图：

pygame中的反复游戏，使用递归矩形。（pygame）

1 个答案: