这是我创建的代码，它将是一个简单的2D游戏。我在制作另一个游戏时尝试使用类，以使其功能更强大、更有条理。但问题是，当我运行代码并尝试在main（）函数中移动玩家时，当我按下按钮时，玩家的位置并没有改变。

import pygame as pg

\#------------------------------------------------------------------------------------

# Colors

RED = (255,0,0)
GREEN = (0, 255, 0)
BLUE = (0,0,255)
WHITE = (255,255,255)
BLACK = (0,0,0)
\#------------------------------------------------------------------------------------

# Constants

FPS = 60
WIDTH, HEIGHT = 1400, 900
P_VEL = 10
\#------------------------------------------------------------------------------------

# Variables

\#------------------------------------------------------------------------------------

# Objects

\#------------------------------------------------------------------------------------

# Fonts

\#------------------------------------------------------------------------------------

# Sprites

\#------------------------------------------------------------------------------------

# Sounds

\#------------------------------------------------------------------------------------
WINDOW = pg.display.set_mode((WIDTH,HEIGHT))
pg.display.set_caption("Game Project")

\#------------------------------------------------------------------------------------
class Hero:
    def __init__(self, x_cord, y_cord, width, height):
        self.xc = x_cord
        self.yc = y_cord
        self.width = width
        self.height = height
        self.hero = pg.Rect(self.xc,self.yc,self.width,self.height)

    def player_movement(self, keys_pressed):
        if keys_pressed[pg.K_d]:
            self.xc += P_VEL
        if keys_pressed[pg.K_a]:
            self.xc -= P_VEL
        if keys_pressed[pg.K_w]:
            self.yc -= P_VEL
        if keys_pressed[pg.K_s]:
            self.yc += P_VEL
    
    def draw(self):
        pg.draw.rect(WINDOW, GREEN, self.hero)

player = Hero(500,400,40,60)

def gravis():
    WINDOW.fill(BLACK)
    player.draw()
    pg.display.update()

def main():
    clock = pg.time.Clock()
    run = True
    while run:
        clock.tick(FPS)
        for event in pg.event.get():
            if event.type == pg.QUIT:
                run = False

        keys_pressed = pg.key.get_pressed()
        
        player.player_movement(keys_pressed)
    
        gravis()

main()

我试着在youtube上搜索答案，并查看代码，但我什么也没找到。