Python pygame - 带有 float 的平滑移动

Question

所以我是Python新手，我正在尝试通过编写一个小汽车游戏来学习pygame模块。游戏的“引擎”基于滚动背景，当用户按下“向上”键时，背景会向下移动。

我试图使汽车减速(当用户释放“向上”键时)而不是立即停止。为此，我尝试使用 float for 循环(使用 numpy 模块)将背景移动的速度从 5 降低到 0 -0.1，但它无法正常工作。实际发生的情况是，当我释放“向上”键时，游戏卡住了一秒钟，然后背景不平滑地向下移动了几个像素。

这是我的代码，希望你能帮我解决这个问题:

import pygame
import numpy

pygame.init()
clock = pygame.time.Clock()
run = True

# screen & bg setting
wnw = 500
wnh = 700
wn = pygame.display.set_mode((wnw, wnh))
bgcolor = (70, 190, 255)
bg = pygame.image.load('road.jpg')
bgy = 0
bgy2 = -bg.get_height()

# loading objects
class Car():
    sprite = pygame.image.load('car.gif')
    w = 100
    h = 100
    x = 200
    y = 350
    ver_spd = 5
    hor_spd = 2
car = Car()

def drawbg():
    wn.blit(bg, (0, bgy))
    wn.blit(bg, (0, bgy2))
drawbg()

while run:

    clock.tick(60)

    # keys binding
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
        if car.x + car.hor_spd > 0:
            drawbg()
            car.x -= car.hor_spd
    if keys[pygame.K_RIGHT]:
        if car.x + car.hor_spd < wnw - car.w:
            drawbg()
            car.x += car.hor_spd
    if keys[pygame.K_UP]:
        if car.y - car.ver_spd > 0:
            bgy, bgy2 = bg_movement(bgy, bgy2, car.ver_spd)
    def bg_movement(bgy, bgy2, spd):
        drawbg()
        bgy += float(spd)
        bgy2 += float(spd)
        if bgy > bg.get_height():
            bgy = -bg.get_height()
        if bgy2 > bg.get_height():
            bgy2 = -bg.get_height()
        return bgy, bgy2


    for event in pygame.event.get():
        if event.type == pygame.KEYUP:
            if event.key == pygame.K_UP:
                for i in numpy.arange(5.0, 0.0, -0.1):
                    bgy, bgy2 = bg_movement(bgy, bgy2, float(i))

    wn.blit(car.sprite, (car.x, car.y))

    pygame.display.update()
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        print(event)

pygame.quit()

Answer 1

第一个 pygame.event.get()获取所有消息并将它们从队列中删除。因此，第一个或第二个循环都会获取一个事件，但两个循环都不会获取所有事件。这导致一些事件似乎被错过。
在您的应用程序中实现 1 个事件循环。

一旦释放UP，您就必须设置减速状态。只要decelerate > 0，减少变量并将每帧中的焦点向前移动一定量:

def drawbg():
    wn.blit(bg, (0, int(bgy)))
    wn.blit(bg, (0, int(bgy2)))
drawbg()

def bg_movement(bgy, bgy2, spd):
        bgy += float(spd)
        bgy2 += float(spd)
        if bgy > bg.get_height():
            bgy = -bg.get_height()
        if bgy2 > bg.get_height():
            bgy2 = -bg.get_height()
        return bgy, bgy2

decelerate = 0
while run:

    clock.tick(60)

    # keys binding
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
        if car.x + car.hor_spd > 0:

            car.x -= car.hor_spd
    if keys[pygame.K_RIGHT]:
        if car.x + car.hor_spd < wnw - car.w:
            car.x += car.hor_spd
    if keys[pygame.K_UP]:
        decelerate = 0
        if car.y - car.ver_spd > 0:
            bgy, bgy2 = bg_movement(bgy, bgy2, car.ver_spd)

    if decelerate > 0:
        bgy, bgy2 = bg_movement(bgy, bgy2, decelerate)
        decelerate -= 0.1


    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        if event.type == pygame.KEYUP:
            if event.key == pygame.K_UP:
                decelerate = car.ver_spd


    drawbg()
    wn.blit(car.sprite, (car.x, car.y))

    pygame.display.update()