Box2D b2Body对象没有属性“ GetLinearVelocity”

问题描述

我想用pygame和Box2D在Python上用球制作一个简单的物理游戏，但是当我尝试使用一种众所周知的方法来获取球的速度时，出现了这个错误。可能是什么问题？

class Ball:
    def __init__(self,x,y,radius,world,color,fric=0.3,maxspeed=20,density=0.01,restitution=0.5):
        self.x = x
        self.y = y
        self.radius = radius
        self.fric = fric
        self.maxspeed = maxspeed
        self.density = density
        self.restitution = restitution
        self.color = color

        #body
        self.bodyDef = Box2d.b2BodyDef()
        self.bodyDef.type = Box2d.b2_dynamicBody
        self.bodyDef.position = (x,y)

        self.body = world.CreateBody(self.bodyDef)

        #shape
        self.sd = Box2d.b2CircleShape()
        self.sd.radius = radius

        #fixture
        self.fd = Box2d.b2FixtureDef()
        self.fd.shape = self.sd


        #phys params
        self.fd.density = density
        self.fd.friction = fric
        self.fd.restitution = restitution

        self.body.CreateFixture(self.fd)

player = Ball(width / 3,height / 2,30,(150,150,150))

v = player.body.GetLinearVeLocity()

错误：

Traceback (most recent call last):
  File "D:\projs\Box2d\bonk\main.py",line 60,in <module>
    keyIsDown(pygame.key.get_pressed())
  File "D:\projs\Box2d\bonk\main.py",line 35,in keyIsDomn
    v = player.body.GetLinearVeLocity()
AttributeError: 'b2Body' Object has no attribute 'GetLinearVeLocity'

screenshot of error

解决方法

看来GetLinearVelocity方法仅在C库中可用。 Python包装器仅使用linearVelocity：

v = player.body.linearVelocity

将来，如果您想知道变量类型是什么以及可用的方法\属性，可以使用type和dir函数：

print(type(player.body))  # class name  # <class 'Box2D.Box2D.b2Body'>
print(dir(player.body))   # all methods and properties  # ['ApplyAngularImpulse','ApplyForce',....,'linearVelocity',...]

box2d box2d pygame python