用pymunk定义函数

Question

我在下面的代码中定义了一个名为add_spring的函数

import pymunk
import pymunk.pygame_util
import math

pygame.init()
wid, hei = 800, 700
window = pygame.display.set_mode((wid, hei))


def draw(space, window, draw_options):
    window.fill("white")
    space.debug_draw(draw_options)
    pygame.display.update()

def wall(space, wid, hei):
    rects = [
        [(wid/2, hei - 10), (wid, 20)],
        [(wid/2, 10), (wid, 20)]
    ]
    for pos, size in rects:
        body = pymunk.Body(body_type=pymunk.Body.STATIC)
        body.position = pos
        shape  = pymunk.Poly.create_box(body, size)
        shape.elasticity = 0.4
        shape.friction = 0.5
        space.add(body, shape)

def create_ball(space, radius, mass):
    body = pymunk.Body()
    body.position = (500, 350)
    shape = pymunk.Circle(body, radius)
    shape.mass = mass
    shape.color = (55, 0, 0, 100)
    space.add(body, shape)
    shape.elasticity = 0.9
    shape.friction = 0.4
    return shape

def add_ball(space):
    body = pymunk.Body()
    body.position = (500, 500)
    shape = pymunk.Circle(body, 20)
    shape.mass = 1
    shape.friction = 0.7
    space.add(body, shape)
    return body

def create_ball_a(space, radius, mass):
    body = pymunk.Body(body_type=pymunk.Body.STATIC)
    body.position = (500, 300)
    shape = pymunk.Circle(body, radius)
    shape.mass = mass
    shape.color = (55, 0, 0, 100)
    space.add(body, shape)
    shape.elasticity = 0.9
    shape.friction = 0.4
    return shape

def create_ball_b(space, radius, mass):
    body = pymunk.Body(body_type=pymunk.Body.STATIC)
    body.position = (550, 300)
    shape = pymunk.Circle(body, radius)
    shape.mass = mass
    shape.color = (55, 0, 0, 100)
    space.add(body, shape)
    shape.elasticity = 0.9
    shape.friction = 0.4
    return shape
def add_spring(var1, var2):
    dlx = pymunk.DampedSpring(var1, var2, (0, 0), (0, 0), 5, 70, 0)
    space.add(dlx)



def run(window, wid, hei):
    run = True
    clock = pygame.time.Clock()
    fps = 60
    dt = 1 / fps
    space = pymunk.Space()
    space.gravity = (0, 981)
    big_ball = create_ball(space, 30, 10)
    joina = create_ball_a(space, 5, 10)
    joinb = create_ball_b(space, 5, 10)
    j = pymunk.DampedSpring(big_ball.body, joina.body, (0, 0), (0, 0), 5, 70, 0)
    space.add(j)
    add_spring(joina, big_ball)
    space.add(pymunk.DampedSpring(big_ball.body, joinb.body, (0, 0), (0, 0), 100, 100, 10))
    wall(space, wid, hei)
    draw_options = pymunk.pygame_util.DrawOptions(window)

    while run:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
                break
        draw(space, window, draw_options)
        space.step(dt)
        clock.tick(fps)
    pygame.quit()

if __name__ == "__main__":
    run(window, wid, hei)

但是，当我运行它时，会出现下面的错误。

pygame 2.0.1 (SDL 2.0.14, Python 3.8.9)
Hello from the pygame community. https://www.pygame.org/contribute.html
Traceback (most recent call last):
  File "e:/pymunk/2D-cloth-simulation/string_d.py", line 104, in <module>
    run(window, wid, hei)
  File "e:/pymunk/2D-cloth-simulation/string_d.py", line 88, in run
    add_spring(joina, big_ball)
  File "e:/pymunk/2D-cloth-simulation/string_d.py", line 71, in add_spring
    dlx = pymunk.DampedSpring(var1, var2, (0, 0), (0, 0), 5, 70, 0)
  File "C:\Users\Kishlay\AppData\Local\Programs\Python\Python38\lib\site-packages\pymunk\constraints.py", line 617, in __init__
    _constraint = lib.cpDampedSpringNew(
TypeError: initializer for ctype 'struct cpBody *' must be a cdata pointer, not Body

当我在不为它定义函数的情况下做同样的事情时，它可以工作，但是为了保持代码的干净，我需要它将它转换成一个函数，这样我就可以不麻烦地多次完成它。

Answer 1

你有两个错误。

1. 它需要.body (就像代码中的其他DampedSpring一样) 您可以从var1，var2： dlx = pymunk.DampedSpring(var1.body，var2.body，(0，0)，(0，0)，5，70，0) 或者你可以发送.body： add_spring(joina.body，big_ball.body)
2. 您还必须将space发送到此函数(要运行space.add() ) 使它发挥作用： def add_spring(space，var1，var2)： 发送到功能： Add_spring(空间，joina.body，big_ball.body)

完整代码：

import pygame
import pymunk
import pymunk.pygame_util
import math

# --- constants ---  # PEP8: `UPPER_CASE_NAMES`

WIDTH = 800
HEIGHT = 700
FPS = 60

# --- functions ---  # PEP8: all function before main code

def draw(space, window, draw_options):
    window.fill("white")
    space.debug_draw(draw_options)
    pygame.display.update()

def wall(space, width, height):
    rects = [
        [(width/2, height - 10), (width, 20)],
        [(width/2, 10), (width, 20)]
    ]
    
    for pos, size in rects:
        body = pymunk.Body(body_type=pymunk.Body.STATIC)
        body.position = pos
        
        shape  = pymunk.Poly.create_box(body, size)
        shape.elasticity = 0.4
        shape.friction = 0.5
        
        space.add(body, shape)

def create_ball(space, radius, mass):
    body = pymunk.Body()
    body.position = (500, 350)
    
    shape = pymunk.Circle(body, radius)
    shape.mass = mass
    shape.color = (55, 0, 0, 100)
    shape.elasticity = 0.9
    shape.friction = 0.4

    space.add(body, shape)
    
    return shape

def add_ball(space):
    body = pymunk.Body()
    body.position = (500, 500)
    
    shape = pymunk.Circle(body, 20)
    shape.mass = 1
    shape.friction = 0.7
    
    space.add(body, shape)
    
    return body

def create_ball_a(space, radius, mass):
    body = pymunk.Body(body_type=pymunk.Body.STATIC)
    body.position = (500, 300)
    
    shape = pymunk.Circle(body, radius)
    shape.mass = mass
    shape.color = (55, 0, 0, 100)
    shape.elasticity = 0.9
    shape.friction = 0.4
    
    space.add(body, shape)
    
    return shape

def create_ball_b(space, radius, mass):
    body = pymunk.Body(body_type=pymunk.Body.STATIC)
    body.position = (550, 300)
    
    shape = pymunk.Circle(body, radius)
    shape.mass = mass
    shape.color = (55, 0, 0, 100)
    shape.elasticity = 0.9
    shape.friction = 0.4

    space.add(body, shape)
    
    return shape

def add_spring(space, body1, body2):
    dlx = pymunk.DampedSpring(body1, body2, (0, 0), (0, 0), 5, 70, 0)
    
    space.add(dlx)
    
    return dlx

def run(WIDTH, HEIGHT):
    pygame.init()
    window = pygame.display.set_mode((WIDTH, HEIGHT))

    dt = 1 / FPS

    clock = pygame.time.Clock()
    
    space = pymunk.Space()
    space.gravity = (0, 981)
    
    big_ball = create_ball(space, 30, 10)
    joina = create_ball_a(space, 5, 10)
    joinb = create_ball_b(space, 5, 10)
    
    j = pymunk.DampedSpring(big_ball.body, joina.body, (0, 0), (0, 0), 5, 70, 0)
    space.add(j)
    
    add_spring(space, joina.body, big_ball.body)
    
    space.add(pymunk.DampedSpring(big_ball.body, joinb.body, (0, 0), (0, 0), 100, 100, 10))
    
    wall(space, WIDTH, HEIGHT)
    draw_options = pymunk.pygame_util.DrawOptions(window)

    run = True
    while run:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
                break
            
        draw(space, window, draw_options)
        
        space.step(dt)
        clock.tick(FPS)
        
    pygame.quit()

if __name__ == "__main__":
    run(WIDTH, HEIGHT)

PEP 8 -- Python代码样式指南