depends on if you can create enough slope down to keep the water out.
or the other option is raise up the floor to accommodate for the slope.
also possible is by adding a lip (3" at lest) to keep water in. but then you have to step over
I am assuming that your shower head is not spraying towards the door, or past it. if so you might have to at least use a shower curtain. or if you can afford it, move the plumbing.
you can look up the amount of slope on do it your self web sites (google, floor slope for shower) or something to that effect.