Depends partly on the direction of the spray in relation to the door. Is the door on one end and the shower head on the opposite wall? Or is the door on one end and the shower head on a side wall? What size shower are you planning? Do you have sketch/floor plan you can post?

I want to know this, too! (Our partial wall comes out from the same wall as the shower head. I think that's the only way I've seen these-- otherwise, you'd better have a wet room for sure!)

Depends on how wide the shower is too.

probably a little late to post this for the OP but wanted to say (as I've said numerous times), we love our shower without a door. The shower is 5X5 with a fixed shower on one side, handheld shower next to an Envision seat on the other and a rain shower in the middle. we have a linear/trench drain.
Both shower heads are 16 inches from the wall. They can be pointed if want but we usually just leave them the way they are. There is a lot I could say but I will post this picture (which I have posted before). We wanted a setup that would work with a wheel chair if we needed it.
I have put a small mat in front of the sink. There is a small amount of water that sprays onto the matt but not very much. Doesn't make it soggy or anything like that. Helps with my balance which mine is not good. I love the bars. Since we have the Moen digital spa, we didn't need a lot of trim for valves.
We weren't sure about not having a door so we had contractor build it so we could add door later if we wanted. That's not going to happen. I think the doorless shower is probably what I like best about the whole room and I REALLY love the room.

Rest of pictures of the room are at:
www.houstonbookclubs.org/hbath

I've been wondering about doorless showers instead of a wide (48 inch) shower stall. Could one fit in roughly the same footprint as the shower stall? Is the cost roughly the same as a shower stall? Who puts these in, anyway? The tile flooring sub? I'm so confused - way too many details right now, and two of our early/main subs are keeping me jumping!

we are planning ours now. No door, no curtain and no glass panels to clean. We will have a trench/linear drain (although my contractor seems surprised by my request) and a curbless design - no threshold to step over as we age. Current dimenions and layout being tweaked, but about 3 to 3 1/2" feet by 6 ft. You might want to google or go on houzz and look at curbless designs. The architect currently has the drain positioned along the long wall (6 ft) but I advised him he may have to relocate to back (short) wall depending on code/slope requirements, I'll let him figure it out.

divod - I am thinking of the same type of drain -but have to find out if we can retro to our BR. We would have to put ours on the back wall as well (short wall)

We are building a house. One of the upstairs bathrooms has a 3'x3' opening. Can I do a doorless shower? Also are prefabricated marble showers nice?

Did you make a typo? What is a 3' X 3' opening? Is that the footprint of the shower? If so, you would need to make the room a wet room.
Here's a wetroom on Houzz that has a relatively small footprint for the shower and no door.
[small wetroom here [(https://www.houzz.com/photos/universal-bathroom-modern-san-francisco-phvw-vp~25801) - wall mounted toilet is recommended though I guess not a hard requirement. They tend to be more expensive than standard wall mounted toilet.

[Here's another - not so pretty but shows the idea[(https://www.houzz.com/photos/european-style-master-bathroom-dc-metro-phvw-vp~304469) Floor plan works well without a shower door but I would have different floor tile, different toilet, different vanity and even different grab bars. YMMV