act 3 scene 3

Are you referring to how the play performed for the King affects Hamlet?

yes exacly 

Hamlet is sure of Claudius's guilt as well as accepting that his father's ghost was honest. Until this point, Hamlet has been ruminating in his head about everything from the guilt of his uncle to the afterlife. Hamlet becomes more direct in his dealings with characters and feels like he is more a man of action.