python pygame将随机坐标星星放在屏幕上但重叠

Question

我试图将星星放在屏幕上并给它们随机的 x,y 坐标

但是当屏幕刷新时，之前的星星仍然在屏幕上，并且与下一个星星重叠

我把setting.screen.fill((255,0,0))为什么这个背景不刷新以前的星星？是什么原因造成的？？？

代码如下:

#!/usr/bin/python
import sys
import pygame as p
from random import randint

#13-1

class Setting():
    def __init__(self,width,height):
        self.w=width
        self.h=height
        self.screen=p.display.set_mode((self.w,self.h),p.RESIZABLE,0)
        p.display.set_caption("EXE 13-1")

class Star(p.sprite.Sprite):
    def __init__(self):
        super().__init__()
        pic=p.image.load("../image/star.jpg").convert_alpha()
        self.image=p.transform.smoothscale(pic,(100,100))
        self.rect=self.image.get_rect()
        self.rect.x=(self.rect.width)/2
    def create(self,setting,stars):
        spacex=setting.w-2*self.rect.x
        numbers=int(spacex/(2*self.rect.x))
        rows=int(setting.h/(2*self.rect.height))
        for row in range(rows):
            for number in range(numbers):
                star=Star()
                star.rect.x=randint(-10,10)+2*self.rect.width*number
                star.rect.y=randint(-10,10)+2*self.rect.height*row
                stars.add(star)
    def blit(self,setting,stars):
        stars.draw(setting.screen)
        # for star in stars.sprites():
        #    setting.screen.blit(star.image,star.rect)


def game():
    p.init()
    setting=Setting(1200,800)
    star=Star()
    stars=p.sprite.Group()
    while True:
        for event in p.event.get():
            if event.type == p.QUIT:
                sys.exit()
            elif event.type == p.KEYDOWN:
                if event.key == p.K_ESCAPE:
                    sys.exit()
        setting.screen.fill((255,0,0))
        star.create(setting,stars)
        star.blit(setting,stars)
        p.display.flip()
game()

Answer 1

引起此问题的原因是，在每个帧中重新创建了整个星星并将其附加到 pygame.sprite.Group 星星。但该组永远不会被清空，并且不断增长:

while True:

   # [...]

   star.create(setting,stars) # <-- adds new objects to Group "stars" in every frame

最简单的解决方案是 empty()每帧中的组

def game():

    # [...]

    while True:

        # [...]

        # remove all stars from the group
        stars.empty()
        # create new stars
        star.create(setting,stars)

但更好的解决方案是将星星保留在组中并随机化它们的位置。请注意，在每一帧中重新创建星星将会对性能产生影响。
在主应用程序循环之前创建星星，并为主应用程序循环中的每个星星设置一个新的随机位置:

class Star(p.sprite.Sprite):

    # [...]

    def create(self,setting,stars):
        spacex=setting.w-2*self.rect.x
        numbers=int(spacex/(2*self.rect.x))
        rows=int(setting.h/(2*self.rect.height))
        for row in range(rows):
            for number in range(numbers):
                star=Star()

                # store row and colume of the stare 
                star.col = number
                star.row = row

                star.randomize()
                stars.add(star)

    # calculate random position
    def randomize(self):
        self.rect.x=randint(-10,10)+2*self.rect.width*self.col
        self.rect.y=randint(-10,10)+2*self.rect.height*self.row

def game():
    p.init()
    setting=Setting(1200,800)
    star=Star()
    stars=p.sprite.Group()
    star.create(setting,stars)
    while True:
        for event in p.event.get():
            if event.type == p.QUIT:
                sys.exit()
            elif event.type == p.KEYDOWN:
                if event.key == p.K_ESCAPE:
                    sys.exit()

        # randomize positions of stars
        for star in stars:
            star.randomize()

        setting.screen.fill((255,0,0))
        star.blit(setting,stars)
        p.display.flip()

<小时/>

最后，我建议从类方法 create 和 blit 中删除 self 参数。只需将星星的图像放置一次就足够了:

class Star(p.sprite.Sprite):
    def __init__(self, col, row, image):
        super().__init__()
        self.image = image
        self.rect = self.image.get_rect()
        self.col, self.row = col, row
        self.randomize()

    def randomize(self):
        self.rect.x=randint(-10,10)+2*self.rect.width*self.col
        self.rect.y=randint(-10,10)+2*self.rect.height*self.row

    def create(setting,stars):
        pic = p.image.load("../image/star.jpg").convert_alpha()
        pic = p.transform.smoothscale(pic,(100,100))
        numbers, rows = setting.w // 100, setting.h // 100
        for row in range(rows):
            for number in range(numbers):
                star=Star(number, row, pic)
                stars.add(star)

    def randomizeStars(stars):
        for star in stars:
            star.randomize()

    def blit(setting,stars):
        stars.draw(setting.screen)

def game():
    p.init()
    setting=Setting(1200,800)
    stars=p.sprite.Group()
    Star.create(setting,stars)
    while True:
        for event in p.event.get():
            if event.type == p.QUIT:
                sys.exit()
            elif event.type == p.KEYDOWN:
                if event.key == p.K_ESCAPE:
                    sys.exit()

        Star.randomizeStars(stars)

        setting.screen.fill((255,0,0))
        Star.blit(setting,stars)
        p.display.flip()