Hi,

I was searching for an algorithm for circle collision and i found this pretty much simple and understandable in the net.

Code:
http://www.emanueleferonato.com/2007/12/06/flash-ball-vs-ball-game-concept/
But in this game,if we dont move the blue circle,the red will come and overlap the blue.How can i stop the red at the boundary of the blue if vx and vy (velocities of blue) is equal to zero?Or keep the red bouncing on blue even if the blue is still?

Please help