Ball

# joe 10/12/2014
import appuifw as A
import graphics as G
import math
import random
rand=random.randint
run=1
def stop():
 global run
 run=0

A.app.screen='full'
A.app.body=c=A.Canvas()
A.app.exit_key_handler=stop
w,h=c.size
img=G.Image.new((w,h))

dt,R=1.0,10
vx=[2,2,2,2]
vy=[2,2,2,2]
px=[rand(20,160),rand(20,160),rand(20,160),rand(20,160)]
py=[rand(20,180),rand(20,180),rand(20,180),rand(20,180)]
color=[0xff0000,0x00ff00,0x0000ff,0xffff00]
nxt=1
while run:
 img.clear(0)
 for i in range(len(px)):
  j=nxt+1
  if (px[i]+dt*vx[i] > w-R) or (px[i]+dt*vx[i] < R):
   vx[i]=-vx[i]
  if (py[i]+dt*vy[i] > h-R) or (py[i]+dt*vy[i] < R):
   vy[i]=-vy[i]
  dx=(px[i]-px[j])+(vx[i]-vx[j])
  dy=(py[i]-py[j])+(vy[i]-vy[j])
  dist=math.sqrt(dx*dx+dy*dy)
  if dist <= (3*R)/2: #2*R
   tempx=vx[i]
   tempy=vy[i]
   vx[i]=vx[j]
   vy[i]=vy[j]
   vx[j]=tempx
   vy[j]=tempy
  px[i]=px[i]+vx[i]*dt
  py[i]=py[i]+vy[i]*dt
  img.ellipse((px[i]-R,py[i]-R,px[i]+R,py[i]+R),fill=color[i])
 c.blit(img)
 A.e32.ao_sleep(0.01)
 A.e32.reset_inactivity()