为什么我的pygame球在使用类时不会加速？

Question

所以我是新来的pygame/python /编码和第一次使用类。我已经做出了一个工作pygame程序的球弹跳和重力加速。但是，现在我使用了课堂，球只似乎以恒定的速度移动。请告诉我我做错了什么，以及如何改变我的代码。提前致谢！

import pygame, sys 


pygame.init() 

red = (255,0,0) 
black = (0,0,0) 
white = (255,255,255) 
blue = (0,0,255) 

pygame.mouse.set_visible(0) 
clock = pygame.time.Clock() 

displaySize = (800,600) 

screen = pygame.display.set_mode(displaySize) 

g = 30 
dt = 0.05 

class ball: 
    def __init__(self, x, y, vx, vy, r,ax,ay, color): 

     dt = 0.05 

     Cd = 0.01 
     m = 5 

     self.ay = ay 
     self.ax = ax 

     self.x = x 
     self.y = y 
     self.r = r 
     self.color = color 

     self.vx = vx 
     self.vy = vx 

def update(self, x, y): 


    x, y = physics() 
    pygame.draw.circle(screen, self.color, (int(round(x)),int(round(y))), self.r) 
    pygame.display.update() 

    def physics(self): 


     self.Dy = Cd*self.vy*abs(self.vy) 
     self.Dx = Cd*self.vx*abs(self.vx) 

     self.Fy = self.m*g - self.Dy 
     self.Fx = -self.Dx 

     self.ay = self.Fy/m 
     self.ax = self.Fx/m 

     self.vy += self.ay*dt 
     self.vx += self.ax*dt 

     self.x +=self.vx*dt 
     self.y +=self.vy*dt 

     return self.x, self.y 

one = ball(100,100,0,0,0,0,30,red) 

while 1: 
    clock.tick(30) 
    screen.fill(blue) 
    one.update() 

    for event in pygame.event.get(): 
     if event.type == pygame.QUIT: 
      pygame.quit() 
      sys.exit() 

Answer 1

self.vx和self.vy应的构造方法，而不是物理方法之内，否则它们的值将被设置回至50和0每次物理方法被称为游戏循环内，导致以恒定的速度。