如何在 PyGame 中滚动背景表面？

Question

我正在尝试在基于 pyGame 的随机地图生成器中设置滚动。但是，我无法弄清楚如何使显示远离 "smearing" 背景，而不是仅仅在其上滚动。我为 Stack Overflow 制作了一个仅显示彩色方块的 MCV 示例。它有同样的问题。

怎样才能让显示滚动不拖屏？

这是我滚动了一下后地图生成器显示的内容：

MCV 示例：

""" This example just displays colored squares. """

import pygame
import sys


def main():

    pygame.init()

    screen = pygame.display.set_mode((800, 800))

    x_pos = 0
    y_pos = 0
    yellow = (255, 255, 0)
    blue = (0, 0, 255)

    # draw pattern of yellow and blue squares
    for y in range(100):
        for x in range(100):

            if (y + x) % 2 == 0:
                pygame.draw.rect(screen, yellow, (x_pos, y_pos, 50, 50))
            else:
                pygame.draw.rect(screen, blue, (x_pos, y_pos, 50, 50))

            x_pos += 50

        y_pos += 50
        x_pos = 0

    while True:  # <-- the pyGame loop

        event = pygame.event.poll()
        pressed = pygame.key.get_pressed()

        # handle window closing
        if event.type == pygame.QUIT:
            break

        # handle scrolling
        if pressed[pygame.K_UP]:
            screen.scroll(0, 2)
        elif pressed[pygame.K_DOWN]:
            screen.scroll(0, -2)
        elif pressed[pygame.K_LEFT]:
            screen.scroll(2, 0)
        elif pressed[pygame.K_RIGHT]:
            screen.scroll(-2, 0)

        # updates what the window displays
        pygame.display.update()

    pygame.quit()
    sys.exit(0)


if __name__ == "__main__":
    # runs the pyGame loop
    main()

初始 MCVE 图像

滚动后MCVE显示：

Answer 1

pygame.Surface.scroll() 没有达到您的预期。它不会无缝滚动表面。请参阅文档：

scroll() Shift the surface image in place

[...] Areas of the surface that are not overwritten retain their original pixel values. [...]

你必须编写你自己的 scroll 函数，将被移出的部分表面放置在表面的另一侧。

例如编写 2 个函数（scrollX 和 scrollY），它们可以 沿轴滚动 ：

def scrollX(screenSurf, offsetX):
    width, height = screenSurf.get_size()
    copySurf = screenSurf.copy()
    screenSurf.blit(copySurf, (offsetX, 0))
    if offsetX < 0:
        screenSurf.blit(copySurf, (width + offsetX, 0), (0, 0, -offsetX, height))
    else:
        screenSurf.blit(copySurf, (0, 0), (width - offsetX, 0, offsetX, height))

def scrollY(screenSurf, offsetY):
    width, height = screenSurf.get_size()
    copySurf = screenSurf.copy()
    screenSurf.blit(copySurf, (0, offsetY))
    if offsetY < 0:
        screenSurf.blit(copySurf, (0, height + offsetY), (0, 0, width, -offsetY))
    else:
        screenSurf.blit(copySurf, (0, 0), (0, height - offsetY, width, offsetY))

if pressed[pygame.K_UP]:
    scrollY(screen, 2)
elif pressed[pygame.K_DOWN]:
    scrollY(screen, -2)
elif pressed[pygame.K_LEFT]:
    scrollX(screen, 2)
elif pressed[pygame.K_RIGHT]:
    scrollX(screen, -2)

如何在 PyGame 中滚动背景表面？

How to scroll the background surface in PyGame?

python

scroll

pygame

2d

python-2.7