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python - 对角线移动使玩家走得更快

问题描述

我有这个简单的移动脚本。

if x > 0:
    if key[pygame.K_a] or key[pygame.K_LEFT]:
        rect_player.move_ip(-1 * speed, 0)
if x < SCREEN_WIDTH - 110:
    if key[pygame.K_d] or key[pygame.K_RIGHT]:
        rect_player.move_ip(speed, 0)
if y > 0:
    if key[pygame.K_w] or key[pygame.K_UP]:
        rect_player.move_ip(0, -1 * speed)
if y < SCREEN_HEIGHT - 110:
    if key[pygame.K_s] or key[pygame.K_DOWN]:
        rect_player.move_ip(0, speed)

当玩家向一个方向移动时，一切都很好。但是当它们沿对角线移动时，它会走得更快。有没有什么办法解决这一问题？

标签： pythonpygame

解决方案

由于pygame.Rect应该代表屏幕上的一个区域，一个pygame.Rect对象只能存储整数数据。

Rect 对象的坐标都是整数。[...]

我建议使用pygame.math.Vector2该问题。将对象的位置存储在一个pygame.math.Vector2对象中：

pos = pygame.math.Vector2(start_x, start_y)

根据键设置方向向量。将向量缩放到speedwith的长度scale_to_length。移动对象并更新rect_player：

key = pygame.key.get_pressed()
up = key[pygame.K_w] or key[pygame.K_UP]
down = key[pygame.K_s] or key[pygame.K_DOWN]
left = key[pygame.K_a] or key[pygame.K_LEFT]
right = key[pygame.K_d] or key[pygame.K_RIGHT]

move = pygame.math.Vector2(right - left, down - up)
if move.length_squared() > 0:
    move.scale_to_length(speed)
    pos += move  
    rect_player.topleft = round(pos.x), round(pos.y)

如果您不关心浮点精度，只需移动矩形：

key = pygame.key.get_pressed()
up = key[pygame.K_w] or key[pygame.K_UP]
down = key[pygame.K_s] or key[pygame.K_DOWN]
left = key[pygame.K_a] or key[pygame.K_LEFT]
right = key[pygame.K_d] or key[pygame.K_RIGHT]

move = pygame.math.Vector2(right - left, down - up)
if move.length_squared() > 0:
    move.scale_to_length(speed)
    rect_player.move_ip(round(move.x), round(move.y))

最小的例子：

import pygame

pygame.init()
window = pygame.display.set_mode((500, 500))
clock = pygame.time.Clock()

rect_player = pygame.Rect(0, 0, 20, 20)
rect_player.center = window.get_rect().center
speed = 5

run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False      

    key = pygame.key.get_pressed()
    up = key[pygame.K_w] or key[pygame.K_UP]
    down = key[pygame.K_s] or key[pygame.K_DOWN]
    left = key[pygame.K_a] or key[pygame.K_LEFT]
    right = key[pygame.K_d] or key[pygame.K_RIGHT]

    move = pygame.math.Vector2(right - left, down - up)
    if move.length_squared() > 0:
        move.scale_to_length(speed)
        rect_player.move_ip(round(move.x), round(move.y))       

    window.fill(0)
    pygame.draw.rect(window, (255, 0, 0), rect_player)
    pygame.display.flip()
    clock.tick(60)

pygame.quit()
exit()

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