Pendulum 2

# pendulum, cuma 1 bola, kalo yg lebih dari 1 apalagi yg pk efek damping / nge-per agk rumit, next time
# joe, 03/01/2015

import appuifw as A
import graphics as G
import math
sin,cos=math.sin,math.cos

class Pend2:
 def __init__(self):
  self.L=150 # length
  self.A=45 # angle
  self.AV=0.0 # angle velocity
  self.dt=0.3 # timestep ++

 def update(self,g):
  # 9.81 = gravitasi
  angleAccel=(-9.81/self.L)*sin(self.A)
  self.AV+=angleAccel*self.dt
  self.A+=self.AV*self.dt

  cX,cY=W/2,H/8
  ballX=cX+(sin(self.A)*self.L)
  ballY=cY+(cos(self.A)*self.L)

  g.line((0,cY,W,cY),0xffffff,width=2)
  g.line((cX,cY,ballX,ballY),0xffffff)
  g.point((cX,cY),0,width=4)
  g.ellipse((ballX-SIZE/2,ballY-SIZE/2,ballX+SIZE/2,ballY+SIZE/2),fill=0)



class App:
 def __init__(self):
  self.run=0
  A.app.screen='full'
  self.c = A.Canvas(redraw_callback=self.redraw,event_callback=None)
  A.app.body=self.c
  A.app.exit_key_handler = self.stop

 def stop(self):
  self.run=0

 def redraw(self,x):
  if BG:
   self.c.blit(BG)

 def play(self):
  self.run=1
  while self.run:
   BG.clear((176,224,230))
   BG.text((5,H-8),u'Pendulum',0,'legend')
   pen.update(BG)
   self.redraw(0)
   A.e32.ao_sleep(1e-04)

W,H=G.sysinfo.display_pixels()
SIZE=20
BG=G.Image.new((W,H))

pen=Pend2()
App().play()