在PyGame中切换显示的曲面允许用户滚动出曲面的边界

我正在用PyGame创建一个随机生成的地图。但是,我遇到了一个问题,如果用户从地图的左上角滚动,并更改显示的PyGame图面,就会发生问题。

问题是,PyGame仍然会在曲面的左上角启动它们,然后允许它们从曲面的边上滚动,因为跟踪这些边的列表, camera_pos ,现在的值不正确。

所有的表面都是相同的尺寸,我想让它使用户在相同的位置,当他们改变显示的表面。但是,我不知道如何设置pygame切换曲面时用户视图的位置。

如何将用户视图的位置切换回曲面切换时的位置?

我在下面举了一个MCV的例子,希望能有所帮助。它不是显示地图,而是在纯色周围绘制边框。我很抱歉要等多久。我不知道怎么把它缩短。

在本例中,滚动是用箭头键完成的。您可以按键盘上的r、g或b来显示不同颜色的表面。

import pygame
import numpy as np
import sys

def scroll_y(display_surface, offset):
    """
    Handles vertical scrolling.

    :param display_surface: A pyGame surface object.
    :param offset: The speed of the scroll
    """

    width, height = display_surface.get_size()

    map_copy = display_surface.copy()

    display_surface.blit(map_copy, (0, offset))

    # handle scrolling down
    if offset < 0:
        display_surface.blit(map_copy,
                             (0, height + offset),
                             (0, 0, width, -offset))

    # handle scrolling up
    else:
        display_surface.blit(map_copy,
                             (0, 0),
                             (0, height - offset, width, offset))


def scroll_x(display_surface, offset):
    """
    Handles horizontal scrolling.

    :param display_surface: A pyGame surface object.
    :param offset: The speed of the scroll
    """

    width, height = display_surface.get_size()

    map_copy = display_surface.copy()

    display_surface.blit(map_copy, (offset, 0))

    # handle scrolling right
    if offset < 0:
        display_surface.blit(map_copy,
                             (width + offset, 0),
                             (0, 0, -offset, height))

    # handle scrolling left
    else:
        display_surface.blit(map_copy,
                             (0, 0),
                             (width - offset, 0, offset, height))


def main():
    """
    This function displays the three surfaces.

    Press r to show the red surface (which is displayed by default).
    Press g to show the green surface.
    Press b to show the blue surface.
    """
    pygame.init()

    window = pygame.display.set_mode((1600, 900))

    red_surface = pygame.Surface([3200, 1800]).convert(window)
    green_surface = pygame.Surface([3200, 1800]).convert(window)
    blue_surface = pygame.Surface([3200, 1800]).convert(window)

    red_surface.fill((255, 145, 145))
    green_surface.fill((145, 255, 145))
    blue_surface.fill((145, 145, 255))

    # draw thick black lines on surface borders
    pygame.draw.rect(red_surface, (0, 0, 0), (0, 0, 3200, 1800), 40)
    pygame.draw.rect(green_surface, (0, 0, 0), (0, 0, 3200, 1800), 40)
    pygame.draw.rect(blue_surface, (0, 0, 0), (0, 0, 3200, 1800), 40)

    display_surface = red_surface.copy()

    camera_pos = np.array([0, 0])

    while True:  # <-- the pyGame loop

        event = pygame.event.poll()

        pressed = pygame.key.get_pressed()

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

        window.blit(display_surface, (0, 0))

        # handle switching display modes
        if pressed[pygame.K_g]:
            display_surface = green_surface
        elif pressed[pygame.K_b]:
            display_surface = blue_surface
        elif pressed[pygame.K_r]:
            display_surface = red_surface

        # handle scrolling, make sure you can't scroll past the borders
        if pressed[pygame.K_UP] and camera_pos[1] > 0:
            scroll_y(display_surface, 5)
            camera_pos[1] -= 5

        elif pressed[pygame.K_DOWN] and camera_pos[1] < (1800 / 2):
            scroll_y(display_surface, -5)
            camera_pos[1] += 5

        elif pressed[pygame.K_LEFT] and camera_pos[0] > 0:
            scroll_x(display_surface, 5)
            camera_pos[0] -= 5

        elif pressed[pygame.K_RIGHT] and camera_pos[0] < (3200 / 2):
            scroll_x(display_surface, -5)
            camera_pos[0] += 5

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

    pygame.quit()
    sys.exit(0)


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