def set_time(self, t):
super(Pendulum, self).set_time(t)
# manually update time and values
self.pivot.set_time(t)
self.weight.set_time(t)
# align to new position unrotate angle zero by 90 degrees
self.weight.do_align(Vector.from_polar(1, self._angle_zero * math.cos(t / (math.sqrt(self.weight.r() / scipy.constants.g))) - math.radians(90)))
def _time_velocity(self):
curtime = self.t
x = self.t
self.set_time(curtime-0.1)
oldweight = Vector.from_vector(self.weight)
self.set_time(curtime)
y = Vector(self.weight.x - oldweight.x, self.weight.y - oldweight.y).r()
return Point(x, y)
def transform(r, point):
x = r[0][0] * point.x + r[0][1] * point.y
y = r[1][0] * point.x + r[1][1] * point.y
return Vector(x, y)