Hi guys,

im trying to figure out, how i can create 2 equal circles hitting each other in the middle of the frame.
the following code creates 2 circles but after they encounter only one of them is moving, but i want them both mobing away from each other and hit again in the middle...

PVector pos, posA, vel, velA, velB;
int rad;
 
void setup()
{
  size(400, 400);
 
  pos = new PVector (width/4, height/2);
  posA = new PVector (width/2, height/2);
  vel = new PVector (0, 0);
  velA = new PVector (-2, 0);
  rad = 20;
 
  //vel = new PVector (.1, 0);
  //velA = new PVector (-1, 0);
 
  velB = new PVector (0, 0);
}
 
void draw()
{
  background(150);
 
  if ( PVector.dist(pos, posA)<rad)
  {
    velB.add(velA);
    velA.mult(0);
    velA.add(vel);
    vel.mult(0);
    vel.add(velB);
    velB.mult(0);
 
    //momentum is preserved
    //work on implementing mass into mix
  }
 
  border();
  borderA();
 
  pos.add(vel);
  posA.add(velA);
 
 
  ellipse(pos.x, pos.y, rad, rad);
 
  ellipse(posA.x, posA.y, rad, rad);
}
 
void border()
{
  if (pos.x > width)
  {
    vel.x = -vel.x;
  }
  if (pos.x < 0)
  {
    vel.x = -vel.x;
  }
  if (pos.y > height)
  {
    vel.y = -vel.y;
  }
  if (pos.y < 0)
  {
    vel.y = -vel.y;
  }
}
 
void borderA()
{
  if (posA.x > width)
  {
    velA.x = -velA.x;
  }
  if (posA.x < 0)
  {
    velA.x = -velA.x;
  }
  if (posA.y > height)
  {
    velA.y = -velA.y;
  }
  if (posA.y < 0)
  {
    velA.y = -velA.y;
  }
}

may you guys can give me some hints how i can manage, that the circles just hitting in the middle and moving back to the left/right of the frame ?

just like in this picture the seccond row:
http://s7.directupload.net/file/d/3130/u54osy2g_jpg.htm

thanks for help :)