Design guidelines for walk-in shower sizing?
You can also look at Wet Zones. These come in a variety of styles but the one we used from Aqua Dry consists of a raised base you fix above the existing floor level.

This base has the correct drainage slopes built in - all you have to do is make sure the floor on which it stands is level. The range includes side and end panels which fit onto this raised area.

The arrangement we have is (approximately):



The shower head (not included in the kit) is virtually directly over the drain and points more or less straight down. We don't get any water outside the shower area beyond a few splashes.

The walls still need to be made waterproof as does the junction between the walls and the base - but the kit comes with all the tape, glue and waterproofing needed. All you need to do is add the shower itself and the tiles.