球体力学问题Python

Question

我试着让一个球在一个盒子里正确的反弹，特别是处理在特定角度的角落和处理一个角落的头部。我有个问题，因为我的球总是从禁区里出来。我有一个函数，它可以告诉你我的球是否在盒子里，它可以处理角落和墙壁。代码如下：

    if ((self._x > self._Grid.getWidth()) or (self._x < 0)):
        print("RandomNode:outside paramaters: x! self._x = %s , self._velx = %s" % (self._x , self._velx))
    if ((self._y > self._Grid.getLength())  or (self._y < 0)):
        print("RandomNode:outside paramaters: y!")
    if ((self._velx + self._x) > self._Grid.getWidth()):
        diff = self._Grid.getWidth()-self._x
        self._velx *= -1
        if (diff == 0):
            self._x -= self._velx
        else:
            self._x+= diff
        tampered = True
        #print("eqn1: self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))

    if (self._velx + self._x < 0):
        diff = self._x
        self._velx *= -1
        if (diff == 0):
            self._x += self._velx
        else:
            self._x-= diff
        tampered = True
        #print("eqn2: self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))


    if ((self._vely + self._y) > self._Grid.getLength()):
        diff = self._Grid.getLength()-self._y
        self._vely *= -1
        if (diff == 0):
            self._y -= self._vely
            if (tampered == True):
                if ((self._velx * -1 == self._vely) or (self._velx == self._vely)):
                    self._x += self._velx
                    self._y += self._vely
                    #print("eqn31:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
                else:
                    self._x += (self._velx - diff)
                    self._y += self._vely
                    #print("eqn32:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
            else:
                tampered = True
                #print("eqn33:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))


        else:
            self._y+= diff
            if (tampered == True):
                if ((self._velx * -1 == self._vely) or (self._velx == self._vely)):
                    self._x += self._velx
                    self._y += self._vely
                    #print("eqn31:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
                else:
                    self._x += (self._velx - diff)
                    self._y += self._vely
                    #print("eqn32:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
            else:
                tampered = True
                #print("eqn33:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))

    if (self._vely + self._y < 0):
        diff = self._y
        self._vely *= -1
        if (diff == 0):
            self._y += self._vely
            if (tampered == True):
                if ((self._velx * -1 == self._vely) or (self._velx == self._vely)):
                    self._x += self._velx
                    self._y += self._vely
                    #print("eqn41:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
                else:
                    self._x += (self._velx + diff)
                    self._y += self._vely
                    #print("eqn42:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
            else:
                tampered = True
                #print("eqn43:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))

        else:
            self._y-= diff
            if (tampered == True):
                if ((self._velx * -1 == self._vely) or (self._velx == self._vely)):
                    self._x += self._velx
                    self._y += self._vely
                    #print("eqn41:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
                else:
                    self._x += (self._velx + diff)
                    self._y += self._vely
                    #print("eqn42:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
            else:
                tampered = True
                #print("eqn43:self._x = %s , self._y = %s , self._velx= %s, self._vely= %s" % (self._x, self._y, self._velx, self._vely))
    return tampered

我不知道为什么它不起作用。显然x和y是它的坐标。Velx和Vely是它的x和y速度。Tampered是一个布尔值，它阻止球正常移动，只在check内移动。在

这是我的问题。这个代码有什么问题？或者……有没有一个用python编写的模板，或者在任何地方，或者你曾经使用过的代码，能完成我正在尝试处理和做的事情？请随意修改代码，让我知道。任何与这个问题已经解决的链接也将是伟大的。谢谢。在

Answer 1

重写这段代码。这对你想解决的简单问题来说太复杂了。在

首先，球的二维运动只是2个一维问题。你可以完全分开X轴和Y轴。例如，打一个角就相当于在X轴上撞到墙+在Y轴撞到墙。在X轴上撞到一堵墙只会使X速度倒转（如果你想模拟的话，可能会损失一些能量）。在Y轴上撞击墙壁会使Y轴速度反转。在

第二个，因为X和Y的处理非常相似，所以从中提取一个方法

def handle_axis_movement(location, velocity):
    "returns updated location and velocity"
    ...

self.x, self.vel_x = handle_axis_movement(self.x, self.vel_x)
self.y, self.vel_y = handle_axis_movement(self.y, self.vel_y)

这将减少一半的代码（和错误）。在

第三，不必分别处理diff==0和diff<；0。这两种情况都意味着球撞到了墙上，并且应该反转它的速度。然后你应该更正位置，以说明它不可能穿过墙。在

^{pr2}$

Answer 2

当pymunk对你这么好的时候，你不应该重新发明这个轮子。；）