球物理问题Python

Question

我试图让球在盒子内正确弹跳，特别是以特定角度处理角球并正面处理角球。我有一个问题，因为我的球总是从盒子里出来。我有这个函数可以告诉我的球是否开箱即用，并且它可以处理角落和墙壁。代码是这样的：

    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。 x和y显然是它的坐标。 Velx 和 Vely 是其 x 和 y 速度。 Tampered 是一个布尔值，它会阻止球正常移动并且只能在检查范围内移动。

这是我的问题。这段代码有什么问题？或者......是否有一个用Python编写的模板在网络上的某个地方或任何地方，或者您使用过的代码可以完成我想要处理和做的事情？请随意修改代码，请告诉我。任何已解决的链接也都很棒。谢谢。

Answer 1

重写这段代码。对于您要解决的简单问题来说，它太复杂了。

首先，球的 2D 运动只是 2 个 1D 问题。你可以把X和Y完全分开。比如撞角就完全相当于X轴撞墙+Y轴撞墙。在 X 中撞墙只会反转 X 速度（如果你想模拟的话，可能会损失一些能量）。在 Y 方向撞墙会反转 Y 方向的速度。

第二，由于 X 和 Y 的处理非常相似，因此从中提取一个方法

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)

，这会将代码量（和错误）减少一半。

第三，不必单独处理 diff==0 和 diff<0。这两种情况都意味着球撞到了墙上，并且应该反转其速度。然后您应该更正位置以考虑到它无法穿过墙壁的事实。

location += velocity
if location > max_bound:
    location = max_bound - (location - max_bound)
    velocity *= -1
if location < min_bound:
    location = min_bound - (location - min_bound)
    velocity *= -1       

Answer 2

当 pymunk 为您做的这么好时，您不应该重新发明这个轮子。 ;)