python - 是什么导致这些物体与 pymunk 一起飞向左侧？

Question

最近我一直在尝试用 pymunk 制作一个简单的游戏。我的目标(目前)是让盒子受到重力影响，并在调用 up() 函数时“跳跃”。

这是我的代码。

import pygame
from pygame.locals import *
from pygame.color import *
import pymunk
import pymunk.pygame_util

#constants
WALL_BOUNCINESS = 0
FLOOR_FRICTION = 1
accuracy=1
WALL_PADDING=5


#pygame initiation stuff
pygame.init()
width,height=1500,750
screen = pygame.display.set_mode((width, height))

#main loop initialisations
clock = pygame.time.Clock()
running = True

#physics things
space=pymunk.Space()
space.gravity=(0,-900)

#where the magic happens
draw_options = pymunk.pygame_util.DrawOptions(screen)

#boundaries
wall_body = space.static_body
walls = [pymunk.Segment(wall_body, (WALL_PADDING,height-WALL_PADDING), (width-WALL_PADDING,height-WALL_PADDING),1),
    pymunk.Segment(wall_body, (WALL_PADDING,height-WALL_PADDING), (WALL_PADDING,WALL_PADDING), 1),
    pymunk.Segment(wall_body, (WALL_PADDING,WALL_PADDING), (width-WALL_PADDING,WALL_PADDING), 1),
    pymunk.Segment(wall_body, (width-WALL_PADDING,WALL_PADDING), (width-WALL_PADDING,height-WALL_PADDING),1)]
for wall in walls:
    wall.elasticity = WALL_BOUNCINESS
    wall.friction = FLOOR_FRICTION
space.add(walls)

#keybindings
keybindings={}

#adding objects

class player(): #using a class for neatness, not instantiation purposes
    def __init__(self, starting_coords, keyset_LUR=None):

        x,y=starting_coords[0], starting_coords[1]

        mass=10
        inertia = pymunk.moment_for_box(mass, (100,100))

        self.body = pymunk.Body(mass, inertia)

        self.shape = pymunk.Poly(self.body,((x,y),(x+100,y),(x+100,y+100),(x,y+100)))
        self.shape.elasticity = 0
        self.shape.friction = 0.5

        space.add(self.body, self.shape)

        if keyset_LUR:
            funcs=iter((self.left, self.up, self.right))
            for key in keyset_LUR:
                keybindings[key]=next(funcs)

    def left(self):...
    def right(self):...
    def up(self):
        self.body.apply_impulse_at_local_point((0,100))


p1=player((100,100),(K_a,K_w,K_d))
p2=player((1300,100),(K_LEFT,K_UP,K_RIGHT))

#main løóp
while running:
    for event in pygame.event.get():
        if event.type == QUIT: running = False
        elif event.type == KEYDOWN:
            if event.key in keybindings: keybindings[event.key]()

    screen.fill(THECOLORS["white"])

    space.debug_draw(draw_options) #so happy this exists

    dt=1/(60*accuracy)
    for _ in range(accuracy):
        space.step(dt)

    pygame.display.flip()
    clock.tick(60)

对我的非正式评论表示歉意。我尝试使用简单的变量名称，以便代码不太难以理解。我相信问题出在玩家类别上，因为它控制方 block 的行为。我的物理知识很差，而且我不太理解惯性的概念，所以如果我做了一个与物理学相关的基本概念有关的错误，我真的很感激任何可以帮助消除我的误解的解释。这就是它目前的行为方式。

PS。我正在尝试自学 pymunk/python，并且对这两者中的任何一个都没有接受过正规教育，因此我对任何“非正统”代码表示歉意，希望它不会太难理解。

谢谢:)

Answer 1

问题是玩家框没有居中。盒子的重心位于世界坐标中的 (0,0) 处。

因此，您要做的是将多边形形状设置为一个盒子 (-50,-50) 到 (50,50)。然后，为了将其放置在您想要的位置，您可以移动形状所附着的实体。

所以，首先替换

    self.shape = pymunk.Poly(self.body,((x,y),(x+100,y),(x+100,y+100),(x,y+100)))

与

    self.shape = pymunk.Poly(self.body,((-50,-50),(50,-50),(50,50),(-50,50)))

然后将 body 位置设置为 x,y

    self.body.position = x,y