A Streetcar Named Desire- How does Williams portray Stanley?

Williams use of stage directions brings out Stanley's animalistic behaviour towards others and to help give the audience an understanding to how he might move on stage. In scene 10 when Stanley is about to attack Blanche the stage directions explain "he springs towards her." The springing motion makes him sound like some sort of a jungle cat, pouncing on its pray. It gives the audience an idea that Stanley is some sort of predator that only wants one thing from Blanche as he says it was destiny that he was going to rape her or attack her in some way.