python - 我的 Pygame Flappy Bird 克隆中的管道出现滞后和摇晃，而不是流畅移动

Question

下面是创建和管理游戏管道的基本代码:

import pygame as pg
import sys,os,math,time,random

# colours
white = (255,255,255)
red = (255,0,0)
green = (0,255,0)

# general stuff
WIDTH = 1024
HEIGHT = 576
FPS = 60

# other
all_events = [pg.QUIT, pg.ACTIVEEVENT, pg.KEYDOWN, pg.KEYUP, pg.MOUSEMOTION,
              pg.MOUSEBUTTONUP, pg.MOUSEBUTTONDOWN, pg.VIDEORESIZE,
              pg.VIDEOEXPOSE, pg.USEREVENT]

pg.init()
screen = pg.display.set_mode((WIDTH, HEIGHT))
clock = pg.time.Clock()

# Class to manage Pipes
class Pipe_Manager:

    def __init__(self):
        self.pipe_width = 50
        self.pipes = []
        self.pipe_speed = 5
        self.max_tick = 75
        self.spawn_tick = self.max_tick

    def manage_pipes(self):
        self.spawner()
        self.manage()
        self.display()

    def make_pipe(self):

        height = random.randint(100,326)
        gap = random.randint(100,250)
        surf1 = pg.Surface((self.pipe_width, height))
        surf1.fill(green)
        surf2 = pg.Surface((self.pipe_width, HEIGHT - (height + gap)))
        surf2.fill(green)

            # surface, (x,y) and vertical height
        pipe = [surf1, [WIDTH, 0], height]
        pipe2 = [surf2, [WIDTH, height + gap], HEIGHT - (height + gap)]
        self.pipes.append(pipe)
        self.pipes.append(pipe2)

    def spawner(self):  

        if self.spawn_tick == self.max_tick:
            self.make_pipe()
            self.spawn_tick = 0

        self.spawn_tick += 1

    def manage(self):

        for pipe in self.pipes: 

            # move the pipe
            pipe[1][0] -= self.pipe_speed 

            # check if it's off screen           
            if pipe[1][0] + self.pipe_width < 0:
                self.pipes.remove(pipe)

    def display(self):
        for pipe in self.pipes:
            screen.blit(pipe[0], (pipe[1][0], pipe[1][1]))

################################################################################

pg.event.set_blocked(all_events)
pg.event.set_allowed([pg.QUIT, pg.KEYDOWN])

pipe_manager = Pipe_Manager()
loop = True
while loop:
    screen.fill(white)
    pipe_manager.manage_pipes()
    pg.display.update()
    clock.tick(FPS)

管道在水平移动时似乎会摇晃，有时顶部管道与底部管道未对齐。

我希望这不是我的计算机特有的问题，因为我已经抽象出了大量的 flappy-bird-clone 代码，并且这个管道滞后问题的根源一定就在这里。

Answer 1

问题是这段代码:

    for pipe in self.pipes: 

        # move the pipe
        pipe[1][0] -= self.pipe_speed 

        # check if it's off screen           
        if pipe[1][0] + self.pipe_width < 0:
            self.pipes.remove(pipe)

您可以在此处更改当前正在迭代的列表。一旦管道从列表中删除，下一个管道就会错过一个移动步骤。

看一下下面的示例，您可以在其中自己发现问题(看看输出中如何缺少 5，因为我们删除了 4):

>>> l = [1,2,3,4,5,6,7,8,9,10]
>>> for x in l:
...   if x == 4:
...     l.remove(x)
...   print(x)
...
1
2
3
4
6
7
8
9
10
>>>

(其他语言禁止更改您当前迭代的序列是有原因的)。

一个简单的修复方法是首先复制列表:

    for pipe in self.pipes[:]: 

<小时/>

为了使运动更顺畅，请尝试提高帧速率并使用时间步长。这是一种可能的方法:

import pygame as pg
import sys,os,math,time,random

# colours
white = (255,255,255)
red = (255,0,0)
green = (0,255,0)

# general stuff
WIDTH = 1024
HEIGHT = 576
FPS = 120

# other
all_events = [pg.QUIT, pg.ACTIVEEVENT, pg.KEYDOWN, pg.KEYUP, pg.MOUSEMOTION,
              pg.MOUSEBUTTONUP, pg.MOUSEBUTTONDOWN, pg.VIDEORESIZE,
              pg.VIDEOEXPOSE, pg.USEREVENT]

pg.init()
screen = pg.display.set_mode((WIDTH, HEIGHT))
clock = pg.time.Clock()


class Pipe:
    def __init__(self, img, pos):
        self.img = img
        self.pos = pos

# Class to manage Pipes
class Pipe_Manager:

    def __init__(self):
        self.pipe_width = 50
        self.pipes = []
        self.pipe_speed = 0.3
        self.max_tick = 1500
        self.spawn_tick = self.max_tick

    def manage_pipes(self, dt):
        self.spawner(dt)
        self.manage(dt)
        self.display()

    def make_pipe(self):

        height = random.randint(100,326)
        gap = random.randint(100,250)
        surf1 = pg.Surface((self.pipe_width, height))
        surf1.fill(green)
        surf2 = pg.Surface((self.pipe_width, HEIGHT - (height + gap)))
        surf2.fill(green)

        pipe = Pipe(surf1, pg.Vector2(WIDTH, 0))
        pipe2 = Pipe(surf2, pg.Vector2(WIDTH, height + gap))
        self.pipes.append(pipe)
        self.pipes.append(pipe2)

    def spawner(self, dt):

        if self.spawn_tick >= self.max_tick:
            self.make_pipe()
            self.spawn_tick = 0

        self.spawn_tick += dt

    def manage(self, dt):

        for pipe in self.pipes[:]: 

            # move the pipe
            pipe.pos.x -= self.pipe_speed * dt

            # check if it's off screen           
            if pipe.pos.x + self.pipe_width < 0:
                self.pipes.remove(pipe)

    def display(self):
        for pipe in self.pipes:
            screen.blit(pipe.img, pipe.pos)

################################################################################

pg.event.set_blocked(all_events)
pg.event.set_allowed([pg.QUIT, pg.KEYDOWN])

pipe_manager = Pipe_Manager()
loop = True
dt=0
while loop:
    for e in pg.event.get():
        if e.type == pg.QUIT:
            loop = False
    screen.fill(white)
    pipe_manager.manage_pipes(dt)
    pg.display.update()
    dt=clock.tick(FPS)