They will ignore the current scrollfactor that was set in the level.
setting it to a negative number will cause the background the scroll in the opposite direction. This can be useful for those background effects that make the background look sort of circular in a way.
These two properties adds another layer into what you can do with backgrounds though may only be situational
"scrollx":(any integer) "scrolly":(any integer)
They will ignore the current scrollfactor that was set in the level. setting it to a negative number will cause the background the scroll in the opposite direction. This can be useful for those background effects that make the background look sort of circular in a way. These two properties adds another layer into what you can do with backgrounds though may only be situational