# Ball.py by Ed Suominen
# Drag the ball around by an elastic string.
# Adapted from the AnalogClock example that comes with Pythonista
# Dedicated to the Public Domain
from scene import *
from math import hypot, atan2
RADIUS = 50
WIDTH = 4
SPEED = 0.04
class Ball(Scene):
def setup(self):
self.location = self.size/2
circle = ui.Path.oval(0, 0, 2*RADIUS, 2*RADIUS)
circle.line_width = 6
shadow = ('black', 0, 0, 15)
self.face = ShapeNode(circle, 'white', '#cccccc', shadow=shadow)
self.add_child(self.face)
self.vector = ShapeNode(
ui.Path.rounded_rect(0, 0, 100, WIDTH, 3), 'red')
self.vector.anchor_point = (0, 0.5)
self.face.add_child(self.vector)
self.face.add_child(
ShapeNode(ui.Path.oval(0, 0, 2*WIDTH, 2*WIDTH), 'red'))
self.did_change_size()
def touch_began(self, touch):
self.location = touch.location
def touch_moved(self, touch):
self.location = touch.location
def update(self):
d = self.location - self.face.position
xy = self.face.position + SPEED * d
self.face.position = xy
length = hypot(*d)
if length == 0:
w = 0
else:
self.vector.rotation = atan2(d[1]/length, d[0]/length)
if length < RADIUS:
w = 2*WIDTH
else:
w = 2*WIDTH * RADIUS / length
self.vector.size = (0.93*length, w)
def did_change_size(self):
self.face.position = self.size/2
scene = Ball()
run(scene)
