import pygame

pygame.init()

win = pygame.display.set_mode((200, 400))  # 画布窗口的大小

pygame.display.set_caption("first game")  # 窗口标题

x, y = 85, 300  # 方块的起点

width, height = 30, 30  # 方块的宽，高

speed = 5  # 速度

run = True

isJump = False

t = 10

while run:

    # 防止cpu占用过高

    pygame.time.delay(10)

    for event in pygame.event.get():

        if event.type == pygame.QUIT:

            run = False

    keys = pygame.key.get_pressed()

    # 方向箭头响应

    if not (isJump):

        if keys[pygame.K_LEFT] and x > 0:

            x -= speed

        if keys[pygame.K_RIGHT] and x < win.get_size()[0] - width:

            x += speed

        if keys[pygame.K_UP] and y > 0:

            y -= speed

        if keys[pygame.K_DOWN] and y < win.get_size()[1] - height:

            y += speed

        if keys[pygame.K_SPACE]:

            isJump = True

    else:

        if t >= -10:

            a = 1  # 前半段减速上跳

            if t < 0:

                a = -1  # 后半段加速下落

            y -= 0.5 * a * (t ** 2)  # 匀加速直线运动的位移公式

            if y < 0:

                y = 0  # 防止跳出边界

            t -= 1

        else:

            isJump = False

            t = 10

    # 将每一帧的底色先填充成黑色

    win.fill((0, 0, 0))

    # 画方块

    pygame.draw.rect(win, (255, 0, 0), (x, y, width, height))

    # 更新画布

    pygame.display.update()

pygame.quit()