purple shirt is jack , the one sitting is Ralph , the other one is Simon
Carrying a stick sharpened into a makeshift spear,, Jack trails a pig through the thick jungle, but it evades him.
Irritated, he walks back to the beach, where he finds Ralph and Simon at work building huts for the younger boys to live in
Ralph is irritated because the huts keep falling and no one will help him build them but Simon . As Ralph and Simon work, most of the other boys splash about and play in the lagoon.