如何在PyGame中按时间增量在屏幕上显示精灵

Question

I'm making a game in Pygame in which the some characters appear on one side of the screen and move to the other, where they teleport to the place they started from and do it again. I want the sprites to appear one at a time, with a random time increment between their spawning. I have created a class for the sprites, and I have put them in a group called "monsters". My blitting them looks like this:

for monster in monsters:
            monster.render(screen)
            time.sleep(0.5)

What this does is make the screen go black until all the monsters spawn. I want them to spawn one at a time and for the player to be able to see that. Here's the whole class that code above is in:

import pygame, sys, random, time
from monster import *

pygame.init()

class Main:
    clock = pygame.time.Clock()

    screenSize = (500,500)
    background = pygame.image.load("C:/Users/Nathan/PycharmProjects/Monsters II A Dark Descent/images/background.jpg")

    screen = pygame.display.set_mode(screenSize)
    pygame.display.set_caption("MONSTERS!")

    monsters = pygame.sprite.Group()

    counter = 0

    x = 450
    while counter < 5:
            y = random.randint(50,450)
            monster = Monster(x,y)
            monsters.add(monster)
            counter = counter + 1

    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()

        screen.blit(background,(0,0))

        for monster in monsters:
            monster.render(screen)
            time.sleep(0.5)


        x=x-1

        clock.tick(60)

        pygame.display.flip()


Main()

I am also having a second issue. I want the sprites to move a random speed (their current position(x) plus a random number) once they spawn. I also want them to teleport where they started and do it again once they reach the end of the screen. Here is the sprite movement class:

def move(self):
        if(self.x > 500):
            self.x = 450
        self.x -= random.randint(1,5)

Currently them move at varying speeds and just go off the edge of the screen. Here is the whole sprite class:

import random, pygame

class Monster(pygame.sprite.Sprite):

    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)
        self.x = x
        self.y = y
        self.image = pygame.image.load("C:\Users\Nathan\PycharmProjects\Monsters II A Dark Descent\images\monster.png")

    def move(self):
        if(self.x > 500):
            self.x = 450
        self.x -= random.randint(1,5)

    def render(self, screen):
        screen.blit(self.image, (self.x, self.y))

Thank you for your time. If you need any more details let me know.

Answer 1

Nothing will happen during

time.sleep(...)

so the whole game stops while you wait for each monster to be blit ted.

You need to allow the while True loop to keep running, but control the monsters that are being displayed. For example, you could keep a count of visible_monsters which is added to after a suitable interval:

elapsed, visible_monsters = 0, 0

while True:

    elapsed += clock.tick(60)

    for event in pygame.event.get():
        ...

    screen.blit(background,(0,0))

    if elapsed >= 500:
        elapsed = 0
        visible_monsters += 1

    for monster in monsters[:visible_monsters]:
        monster.render(screen)

For your second problem, keep the monster 's init_x and init_y so you can reuse them later and check that they are inside the screen when you render them (eg 0 <= self.x <= screenSize[0] ).

Answer 2

To have various sprites appear at different timings you should you use a timer loop as John says. The code he has given is correct. That is the only way you can do this without slowing down the entire game loop.

elapsed, visible_monsters = 0,0

means he is assigning two varables in one line. It could also be written as

elapsed = visible_monsters = 0

Answer 3

time.sleep() would only pause your program obviously and the only way you can spawn your monsters at different timing is using the Clock.tick function, of cause you must have already called the pygame.time.Clock() into a variable. i used that a lot of times in my snake game too. you could also use the Pygame USEREVENT probably you should read the pygame documentation and see how to do cool things with the pygame time module. and the fact that you have two while loops there with no means of ending them probably turns your game surface black while running the game and i feel that jonrsharpe ans is a good go check your code again and just fix the issues