tracker.py

   1 from __future__ import division
   2
   3
   4
   5 class tracker (object):
   6
   7   __slots__ = 'xtol', 'vtol', 'a', 'v', 'x', 'y'
   8
   9   def __init__ (self, a = 0, xtol = 0, vtol = 0):
  10     self.xtol = xtol
  11     self.vtol = vtol
  12
  13     self.a = a
  14     self.v = 0
  15     self.x = 0
  16     self.y = 0
  17
  18   def __str__ (self):
  19     return '(%f -> %f)' % (self.y, self.x)
  20
  21   __repr__ = __str__
  22
  23   def __add__ (self, other):
  24     return self.y + float (other)
  25
  26   def __sub__ (self, other):
  27     return self.y - float (other)
  28
  29   def __mul__ (self, other):
  30     return self.y * float (other)
  31
  32   def __floordiv__ (self, other):
  33     return self.y // float (other)
  34
  35   def __mod__ (self, other):
  36     return self.y % float (other)
  37
  38   def __divmod__ (self, other):
  39     return divmod (self.y, float (other))
  40
  41   def __pow__ (self, other):
  42     return self.y ** float (other)
  43
  44   def __truediv__ (self, other):
  45     return self.y / float (other)
  46
  47   __div__ = __truediv__
  48
  49   def __radd__ (self, other):
  50     return float (other) + self.y
  51
  52   def __rsub__ (self, other):
  53     return float (other) - self.y
  54
  55   def __rmul__ (self, other):
  56     return float (other) * self.y
  57
  58   def __rfloordiv__ (self, other):
  59     return float (other) // self.y
  60
  61   def __rmod__ (self, other):
  62     return float (other) % self.y
  63
  64   def __rdivmod__ (self, other):
  65     return divmod (float (other), self.y)
  66
  67   def __rpow__ (self, other):
  68     return float (other) ** self.y
  69
  70   def __rtruediv__ (self, other):
  71     return float (other) / self.y
  72
  73   __rdiv__ = __rtruediv__
  74
  75   def __iadd__ (self, other):
  76     self.y += float (other)
  77
  78   def __isub__ (self, other):
  79     self.y -= float (other)
  80
  81   def __imul__ (self, other):
  82     self.y *= float (other)
  83
  84   def __ifloordiv__ (self, other):
  85     self.y //= float (other)
  86
  87   def __imod__ (self, other):
  88     self.y %= float (other)
  89
  90   def __ipow__ (self, other):
  91     self.y **= float (other)
  92
  93   def __itruediv__ (self, other):
  94     self.y /= float (other)
  95
  96   __idiv__ = __itruediv__
  97
  98   def __neg__ (self):
  99     return -self.y
 100
 101   def __pos__ (self):
 102     return self.y
 103
 104   def __abs__ (self):
 105     return abs (self.y)
 106
 107   def __float__ (self):
 108     return self.y
 109
 110   def update (self, dt):
 111     a = self.a
 112     v = self.v
 113     x = self.x
 114     y = self.y
 115
 116     if x < y:
 117       a = -a
 118
 119     try:
 120       from math import sqrt
 121       disc = sqrt (v * v / 2 + a * (x - y))
 122
 123       if x < y:
 124         t = (-v - disc) / a
 125       else:
 126         t = (-v + disc) / a
 127     except ZeroDivisionError:
 128       pass
 129
 130     if t >= dt:
 131       dv = a * dt
 132       self.y += (v + dv / 2) * dt
 133       self.v += dv
 134     elif t >= 0:
 135       dv = a * t
 136       self.y += (v + dv / 2) * t
 137       self.v += dv
 138       dt -= t
 139       dv = -a * dt
 140       self.y += (self.v + dv / 2) * dt
 141       self.v += dv
 142     else:
 143       dv = -a * dt
 144       self.y += (v + dv / 2) * dt
 145       self.v += dv
 146
 147     if abs (self.x - self.y) < self.xtol and abs (self.v) < self.vtol:
 148       self.y = self.x
 149       self.v = 0