... and

This is a by two animation sample

But you ask me - What´s the difference between by one and by two animation?

In the by one animation we do a new draw t each frame and in by two the draw what we have in the odd frame is the same the next one. In the others words what i draw in the first frame i´ll repeat in the second and will change the pose only in 3th.

So you ask me - 

But, but, why you do that, uncle Venicius?

Cause when a image is formed in the human eye it stay there for a few seconds until the other image form itself. It´s called retinal persistence. So with the by two animation we can do the scene´s time appears correct to a smooth movement.