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我想在背景上保留图像一秒钟（或更长时间）然后它应该消失，我尝试在 if 语句内部调用的函数（image_draw）中使用 blit，但图像出现的时间很短，如果我在函数 image_draw 中更改了图像的时间，我没有看到任何变化。

在代码中，我有一条粗线连续向右和向左移动，每次它触及其中一个框架边框时，它都会改变方向，当方向改变发生时会出现图像，我的问题是如何控制时间背景上的图像？函数 image_draw 没有帮助，这里是代码。 

import pygame
import sys
import time
import math

from pygame.locals import *

def image_draw(IMAGE, RECT_FOR_IMAGE, IMAGE_TIME ):
    while IMAGE_TIME > 0:
        windowSurface.blit(IMAGE, RECT_FOR_IMAGE)
        IMAGE_TIME -= 1

pygame.init()

windowSurface = pygame.display.set_mode((300, 600), 0, 32)
pygame.display.set_caption("line and image")

WHITE = (255, 255, 255)
BLUE = (0, 0, 255)
GREEN = (0, 255, 0)
BLACK = (0, 0, 0)
MYCOLOR= (200, 240, 50)
OTHER_LINE_COLOR = (180, 0, 0)



OUR_LINE_START_X = 50
OUR_LINE_START_Y = 400
OUR_LINE_END_X = 250
OUR_LINE_END_Y = 400

OTHER_LINE_START_X = 0
OTHER_LINE_START_Y = 415
OTHER_LINE_END_X = 300
OTHER_LINE_END_Y = 415





IMAGE = pygame.image.load("cherry.png")
LEFT_IMAGE = 250
TOP_IMAGE = 530
WIDTH_IMAGE = 40
HIGHT_IMAGE = 40
IMAGE_TIME = 10
RECT_FOR_IMAGE_1 = pygame.Rect(LEFT_IMAGE, TOP_IMAGE, WIDTH_IMAGE, HIGHT_IMAGE)
RECT_FOR_IMAGE_2 = pygame.Rect(LEFT_IMAGE - 200, TOP_IMAGE, WIDTH_IMAGE, HIGHT_IMAGE)
SOUND = pygame.mixer.Sound("pickup.wav")

MOVE_SPEED = 1


DIRECTION = "left"



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



    if DIRECTION == "right" :
        OUR_LINE_START_X += MOVE_SPEED
        OUR_LINE_END_X += MOVE_SPEED

    elif DIRECTION == "left":
        OUR_LINE_START_X -= MOVE_SPEED
        OUR_LINE_END_X -= MOVE_SPEED

    if OUR_LINE_START_X < 0:
        DIRECTION = "right"
        SOUND.play()
        image_draw(IMAGE, RECT_FOR_IMAGE_1, IMAGE_TIME )


    if OUR_LINE_END_X > 300:
        DIRECTION = "left"
        SOUND.play()
        image_draw(IMAGE, RECT_FOR_IMAGE_2, IMAGE_TIME )




    pygame.draw.line(windowSurface, MYCOLOR, (OUR_LINE_START_X, OUR_LINE_START_Y), (OUR_LINE_END_X, OUR_LINE_END_Y), 30)
    pygame.draw.line(windowSurface, OTHER_LINE_COLOR, (OTHER_LINE_START_X, OTHER_LINE_START_Y), (OTHER_LINE_END_X, OTHER_LINE_END_Y), 3)
    pygame.display.update()
    time.sleep(0.02)

先感谢您。

4

1 回答 1

3

您的 while 循环是游戏帧循环。

当您使用 image_draw 绘图时，您在一帧内从 10 倒数到 0，然后对图像进行 blitting。此外，因为您在同名函数内引用 IMAGE_TIME 变量，所以变量的范围仅在该函数内。

正在发生的事情的视觉描述：

Game Loop:
  draw_image:
    10 - 0
      blit
  next frame

为了使这项工作正常工作，您可以将 IMAGE_TIME 变量排除在 image_draw 方法签名之外并使用全局 IMAGE_TIME。从 image_draw 中删除 while 循环，让它在每一帧上修改全局，然后当你想再次绘制图像时需要重置它。

IMAGE_TIME = 10

def image_draw(IMAGE, RECT_FOR_IMAGE):
  if IMAGE_TIME > 0:
    windowSurface.blit(IMAGE, RECT_FOR_IMAGE)
    IMAGE_TIME -= 1

# ... other code left out for brevity

if OUR_LINE_START_X < 0:
    DIRECTION = "right"
    SOUND.play()
    if IMAGE_TIME == 0:
      IMAGE_TIME = 10
    image_draw(IMAGE, RECT_FOR_IMAGE_1)


if OUR_LINE_END_X > 300:
    DIRECTION = "left"
    SOUND.play()
    if IMAGE_TIME == 0:
      IMAGE_TIME = 10
    image_draw(IMAGE, RECT_FOR_IMAGE_2)

还值得指出的是，在 pygame 中控制帧速率的适当方法是创建一个时钟对象并以所需的帧速率对其进行标记：

clock = pygame.Clock()
while True:
  # do your stuff here
  clock.tick(60) # 60 frames per second

这意味着游戏循环每秒将执行大约 60 次，因此您可以通过设置轻松将图像的显示控制为 1 秒IMAGE_TIME = 60。

于 2013-05-24T23:57:16.200 回答