Hello, I've been trying to figure this out for days now, and I'm starting to get pretty frustrated. Right now, I have a game that moves a clicked button (a game piece) to anywhere you touch on the iPhone screen. I set it up so it only allows you to move withen a specific square area around the button. This works great. But now I want to change that square into a circle, and I can't for the life of me figure out how it's done. I'm thinking that I need to find all the x and Y points withen the area of the circle, throw them into an array, and check them against the x and y points of where the user is touching. But I don't know how to set up an equation that figures out every point in a circle. I also don't think this would be very efficient, seeing as how the computer would have to check tens of thousands of points every time the user touches. I've just hit a wall and I can't figure out where else to go from here. Any help at all would be appreciated.