pygame中的加速和减速 [英] Acceleration and Deceleration in pygame
问题描述
我在编码方面没有太多经验，我一直试图让我的角色在按住键时加速到恒定速度并在松开键时减速.我在网上找到了一些代码，但我似乎无法正确地将它实现到我的中.如果你不介意的话，如果你彻底解释了答案会很有帮助，这样我就可以正确地理解我做错了什么.
I do not have much experience in coding, and I have been stuck on trying to make my character accelerate to a constant speed when key is held and decelerate when key is let go of. I found some code online on it but I cannot seem to properly implement it into mine. If you don't mind it would be helpful if you thoroughly explained the answer so I can properly understand what I am doing wrong.
这是我的代码
"""Dot Game"""
#Imports
import pygame, sys
#Constants
WIDTH, HEIGHT = 1000, 1000
TITLE = "Dot."
#pygame initialization
pygame.init()
win = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption(TITLE)
#fps
FPS = 60
fpsclock = pygame.time.Clock()
#colors
bgc = (247, 226, 222)
pc = (152, 193, 217)
pc2 = (61, 90, 128)
ec = (119, 2, 26)
ec2 = (220, 66, 73)
#accel
x_change = 0
y_change = 0
accel_x = 0
accel_y = 0
max_speed = 6
display_width, display_height = pygame.display.get_surface().get_size()
x = display_width * 0.45
y = display_height * 0.8
#Player Class
class Player:
def __init__(self, x, y):
self.x = int(x)
self.y = int(y)
self.radius = 32
self.width = 2
self.color = pc
self.color2 = pc2
self.velX = 0
self.velY = 0
self.left_pressed = False
self.right_pressed = False
self.up_pressed = False
self.down_pressed = False
self.speed = 3
self.hitbox = (self.x -20, self.y -20, 40, 40)
def draw(self, win):
pygame.draw.circle(win, self.color2, (self.x,self.y), 20)
pygame.draw.circle(win, self.color, (self.x,self.y), 14)
self.hitbox = (self.x -20, self.y -20, 40, 40)
#pygame.draw.rect(win,(255,0,0), self.hitbox,2)
def update(self):
self.velX = 0
self.velY = 0
if self.left_pressed:
self.velX = -self.speed
if self.right_pressed:
self.velX = self.speed
if self.up_pressed:
self.velY = -self.speed
if self.down_pressed :
self.velY = self.speed
self.x += self.velX
self.y += self.velY
self.rect = pygame.Rect(int(self.x), int(self.y), 32, 32)
def collide(self):
print('hit')
pass
#Player Initialization
player = Player(WIDTH/2, HEIGHT/2)
#Main Loop
collide = False
while not collide:
for event in pygame.event.get():
if event.type == pygame.QUIT:
collide == True
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
accel_x = -.2
player.left_pressed = True
elif event.key == pygame.K_RIGHT:
accel_x = .2
player.right_pressed = True
elif event.key == pygame.K_UP:
accel_y = -.2
player.up_pressed = True
elif event.key == pygame.K_DOWN:
accel_y = .2
player.down_pressed = True
elif event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT:
accel_x = 0
accel_y = 0
player.left_pressed = False
elif event.key == pygame.K_RIGHT:
accel_x = 0
accel_y = 0
player.right_pressed = False
elif event.key == pygame.K_UP:
accel_x = 0
accel_y = 0
player.up_pressed = False
elif event.key == pygame.K_DOWN:
accel_x = 0
accel_y = 0
player.down_pressed = False
x_change += accel_x # Accelerate.
if abs(x_change) >= max_speed: # If max_speed is exceeded.
# Normalize the x_change and multiply it with the max_speed.
x_change = x_change/abs(x_change) * max_speed
y_change += accel_y # Accelerate.
if abs(y_change) >= max_speed: # If max_speed is exceeded.
# Normalize the x_change and multiply it with the max_speed.
y_change = y_change/abs(y_change) * max_speed
# Decelerate if no key is pressed.
if accel_x == 0:
if x_change > 0:
x_change -= 0.2
if x_change < 0.2:
x_change = 0
elif x_change < 0:
x_change += 0.2
if x_change > -0.2:
x_change = 0
if accel_y == 0:
if y_change > 0:
y_change -= 0.2
if y_change < 0.2:
y_change = 0
elif y_change < 0:
y_change += 0.2
if y_change > -0.2:
y_change = 0
x += x_change # Move the object.
y += y_change
#Draw
win.fill((bgc))
player.draw(win)
#update
player.update()
pygame.display.update()
fpsclock.tick(FPS)
运动本身有效，但没有加速和减速
The movement itself works, however there is no acceleration and deceleration
推荐答案
在你的代码中，速度总是恒定的，因为你设置了 self.velX = 0 和 self.velY = 0 在 update 的开头.因此速度的大小总是 0 或 3.不要重置self.velX 和self.velY.用加速度改变速度，但限制在最大速度.加速度必须是一个小值.只要按下一个键，这个小值就会被添加到每帧一次的速度上.这会慢慢将速度提高到最大.
通过将速度乘以摩擦来提高物理性能.摩擦的值必须小于 1，或者 1 表示没有摩擦:
In your code the speed is always constant because you set self.velX = 0 and self.velY = 0 at the beginning of update. Therefore the amount of the speed is always 0 or 3.
Do not reset self.velX and self.velY. Change the speed with the acceleration, but limit it at the maximum speed. The acceleration must be a small value. As long as a key is pressed, this small value is added to the speed once per frame. This slowly increases the speed to the maximum.
Improve physics by multiplying speed by friction. The value for the friction must be less than 1, or 1 for no friction:
class Player:
def __init__(self, x, y):
# [...]
self.acceleration = 0.1
self.friction = 0.99 # = 1 if you don't want any friction
def update(self):
if self.left_pressed:
if self.velX > -max_speed:
self.velX -= self.acceleration
if self.right_pressed:
if self.velX < max_speed:
self.velX += self.acceleration
if self.up_pressed:
if self.velY > -max_speed:
self.velY -= self.acceleration
if self.down_pressed :
if self.velY < max_speed:
self.velY += self.acceleration
self.x += self.velX
self.y += self.velY
self.velX *= self.friction
self.velY *= self.friction
self.rect = pygame.Rect(int(self.x), int(self.y), 32, 32)
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