3. How to make a 2D Game - Unity 4.3 Tutorial

//best thanks to https://www.youtube.com/channel/UCjWeE1oMa9SKWUSdx0LzcRw

//move all to the place
    topWall.size = new Vector2( mainCam.ScreenToWorldPoint ( new Vector3(Screen.width * 2f,0f,0f )).x,1f  );
//center
//  topWall.center = new Vector2( 0f, mainCam.ScreenToWorldPoint ( new Vector3( 0f, Screen.height, 0f)).y + 0.5f );
  topWall.offset = new Vector2 (0f, mainCam.ScreenToWorldPoint (new Vector3 ( 0f, Screen.height, 0f)).y + 0.5f);

 bottomWall.size = new Vector2 (mainCam.ScreenToWorldPoint (new Vector3 (Screen.width * 2, 0f, 0f)).x, 1f);
 bottomWall.offset = new Vector2 (0f, mainCam.ScreenToWorldPoint (new Vector3( 0f, 0f, 0f)).y - 0.5f);

 leftWall.size = new Vector2(1f, mainCam.ScreenToWorldPoint(new Vector3(0f, Screen.height*2f, 0f)).y);
 leftWall.offset = new Vector2(mainCam.ScreenToWorldPoint(new Vector3(0f, 0f, 0f)).x - 0.5f, 0f);

 rightWall.size = new Vector2(1f, mainCam.ScreenToWorldPoint(new Vector3(0f, Screen.height*2f, 0f)).y);
 rightWall.offset = new Vector2(mainCam.ScreenToWorldPoint(new Vector3(Screen.width, 0f, 0f)).x + 0.5f, 0f);

 //note how it is offset and not center
 //Move the players to a fixed distance from the edges of the screen:
 Player01.position.x = mainCam.ScreenToWorldPoint (new Vector3 (75f, 0f, 0f)).x;
 Player02.position.x = mainCam.ScreenToWorldPoint (new Vector3 (Screen.width -75f, 0f, 0f)).x;