Can (must) P-trap be directly underneath the drain in stand-up shower stall? I'm roughing in a 48"X36" one piece shower stall with a center drain. In the photo I've just got it dry fit. This is the way I "think" it's supposed to go? I can't imagine moving the P-trap any closer to the vent, as I'd have to use another 90. Or, asking another way, can I do it this way? Total distance is 24" to the vent, so I'm good there. A shower with other than a center drain is not an option, this is a stand up shower only, not a tub. The way I envision this is I'll have about 4-6 inches coming out the trap (the "e" in pipe is level with top of crete), then the drain base glued on that. Yes I can easily slope to the vent, picture doesn't show it well. BTW the wye on the vent is already glued in (long time ago), and yes I plan on completing the vent with two couplings, vent is already plumbed to the main vent stack (not pictured) above, and yes, I plan on closing this back up with crete, then the shower stall on top of that. The clean-out in the photo is from the old laundry drain and is no longer connected to anything.