我在pygame中编写了这个物理模拟，并且碰撞机制无法正常工作。当我从墙的上方或左侧将玩家角色与墙碰撞时似乎起作用，而对于底部或右侧的碰撞则无效
一段时间以来，我一直在尝试查找此错误，但对于可能导致此错误的原因我一无所知。我正在使用python 3.7.3和pygame 1.9.5（截止到目前为最新版本）
很抱歉粘贴整个文件，但我不知道问题出在哪里
import pygame # import the pygame library to have access to game building tools
import math
# these variables will be used to hold game objects and draw them
rigid_bodies = []
g = 100
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
PURPLE = (127, 0, 255)
RED = (200, 0, 0)
GREEN = (0, 200, 0)
BLUE = (0, 0, 200)
class RigidBody(pygame.Rect):
"""
represents a rectangular object that acts according to newton's laws of motion
"""
def __init__(self, canvas, color, m, u, x, y, w, h):
"""
called automatically when a new object is created to initialize the object
:param canvas: the canvas on which to draw the object
:param color: the color of the object
:param m: the mass of the object
:param u: Coefficient of friction
:param x: the starting position of the object on the x axis
:param y: the starting position of the object on the y axis
:param w: the width of the object
:param h: the height of the object
"""
super().__init__(x, y, w, h) # initialize the parent Rect object
self.canvas = canvas
self.color = color
self.m = m
self.u = u
self.x_speed = 0 # the speed of the object on the x axis
self.y_speed = 0 # the speed of the object on the y axis
def apply_force(self, axis, F, initiator=None):
"""
used to apply force on the object
:param axis: the axis of the force
:param F: the amount of force to apply
:param initiator: the object that is applying the force
"""
a = F / self.m # calculate the acceleration the object should have
if axis == 'y':
self.y_speed += a
elif axis == 'x':
self.x_speed += a
if initiator:
initiator.apply_force(axis, -1 * F) # apply normal force
print('colliding')
def inertia(self):
"""
shall be run every frame to make the object move according to its speed
if possible and take the necessary steps if not
"""
# go:
self.x += self.x_speed
self.y += self.y_speed
for body in rigid_bodies:
if self.colliderect(body): # if collide with another object:
self.x -= self.x_speed # go back
self.y -= self.y_speed
body.apply_force('x', self.m * self.x_speed, self) # and apply force on that object
body.apply_force('y', self.m * self.y_speed, self)
break
def draw(self):
"""
shall be run every frame to draw the object on the canvas
"""
pygame.draw.rect(self.canvas, self.color, (self.x, self.y, self.w, self.h))
class Controller:
def __init__(self, character, F):
"""
initialize the controller object
:param character: the character to control
:param F: the force to apply to the character for every frame a button is being pressed
"""
self.character = character
self.up = 0 # whether to move up or not
self.down = 0 # whether to move down or not
self.left = 0 # whether to move left or not
self.right = 0 # whether to move right or not
self.F = F
def stop(self):
"""
stops applying force on the object
"""
self.up = 0
self.down = 0
self.left = 0
self.right = 0
def run(self):
"""
shall be run every frame to apply force on the character according to user input
"""
self.character.apply_force('y', -self.F * self.up)
self.character.apply_force('y', self.F * self.down)
self.character.apply_force('x', -self.F * self.left)
self.character.apply_force('x', self.F * self.right)
def main():
"""
the main function contains the main loop
that runs repeatedly while the game is running
"""
crashed = False # tells if the program crashed or if the window was closed
pygame.init() # required to use pygame
canvas = pygame.display.set_mode((1000, 700)) # define the canvas
clock = pygame.time.Clock() # will be used to limit the number of times a loop runs per second
pygame.display.set_caption('the dot game V2')
character = RigidBody(canvas, WHITE, 1000, 0.3, 500, 500, 20, 50) # initialize the character
player = Controller(character, 500) # initialize the controller
rigid_bodies.append(RigidBody(canvas, WHITE, math.inf, 0, 300, 300, 300, 20)) # initialize the wall
while not crashed:
# handle inputs:
for event in pygame.event.get():
if event.type == pygame.QUIT:
crashed = True
elif event.type == pygame.MOUSEBUTTONUP:
pass
elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_UP:
player.up = 1
elif event.key == pygame.K_DOWN:
player.down = 1
elif event.key == pygame.K_LEFT:
player.left = 1
elif event.key == pygame.K_RIGHT:
player.right = 1
elif event.type == pygame.KEYUP:
player.stop()
player.run()
character.inertia()
canvas.fill(BLACK)
character.draw()
for body in rigid_bodies:
body.draw()
pygame.display.update()
clock.tick(60)
if __name__ == '__main__':
main()
我怀疑问题出在“惯性”或“ apply_force”函数上，但我只是无法弄清楚这些函数出了什么问题
角色每次碰到墙壁时都应该停止移动，但是当它从下方或从右侧碰到墙壁时，它会卡住并且只能向上或向左移动
答案 0 :(得分：3)
此问题是由将浮点值强制转换为int引起的，可以通过以下方法解决：
stored_pos = (self.x, self.y)
self.x += self.x_speed
self.y += self.y_speed
for body in rigid_bodies:
if self.colliderect(body): # if collide with another object:
self.x, self.y = stored_pos
注意，
self.x -= self.x_speed self.y -= self.y_speed
不是...的逆运算
self.x += self.x_speed self.y += self.y_speed
例如：a = 2和b = 0.5
int(a + b) == int(2 + 0.5) == 2
int(a - b) == int(2 - 0.5) == 1
解决方案是存储self.x和self.y的原始值
stored_pos = (self.x, self.y)
，并在发生碰撞时将其恢复：
self.x, self.y = stored_pos