I am doing a rough-in for a small bath before they pour the slab. I have the toilet and stack figured out. I am put a bout a 38" x 38" shower in. I know to box it out around the pipe but when I install the trap it will move some amount. Does this mean I should put the pipe coming up from under the slab offset from the center of the shower to allow for the trap? Does anyone have a diagram of this?