//Uses fixed-point-arithmetic.

I64 x[16],y[16],dx[16],dy[16];

U0 Init()
{
  I64 i;
  F64 theta;
  MemSet(x,0,sizeof(x));
  MemSet(y,0,sizeof(y));
  for (i=0; i<16; i++)
  {
    theta=Rand*2*pi;
    dx[i]=I32_MAX*Cos(theta);
    dy[i]=I32_MAX*Sin(theta);
  }
}

U0 Bounce()
{
  CDC *dc=DCAlias;
  I64 i,ch;
  Init;
  try  //Catch <CTRL-ALT-c>
  {
    do
    {
      for (i=0; i<16; i++)
      {
        dc->color=i;
        GrPlot(dc,x[i].i32[1],y[i].i32[1]);
        x[i]+=dx[i];
        y[i]+=dy[i];
        if (!(0<=x[i]<Fs->pix_width<<32))
        {
          x[i]-=dx[i];
          dx[i]=-dx[i];
        }
        if (!(0<=y[i]<Fs->pix_height<<32))
        {
          y[i]-=dy[i];
          dy[i]=-dy[i];
        }
      }
      Yield;
    }
    while (!(ch=ScanChar) || (ch!=CH_SHIFT_ESC && ch!=CH_ESC));
  }
  catch
    PutExcept;
  DCFill(dc);
  DCDel(dc);
}

Bounce;