BuddyPress.org

Is there a way to assign a user’s profile picture with PHP code? I have the link to the desired pictures. What I am trying to do is automatically assign avatars on sign up with the help of an API (registering will access your game’s user data and this comes with a profile picture of your character). I have only found a way to change the default profile picture but for some reason this isn’t helping. I would like to assign a profile picture on sign up to each member individually. What would be the best way of doing this?