Visual Error

The title doesn't really explain much, so take a look at the screenshot.

http://i273.photobucket.com/albums/jj212/Blue9Knight/Error.jpg

I know what I did to cause it, and how to fix it. But I want to know how to fix it witout deleting a huge chunk of my map or starting all the way over. =/

That's ol Doom Builder for ya. Don't worry, it wont show up like that in game, and it may correct itself in 3D mode, eventually.

You don't quite understand what I've done here, take a look at an ingame screenshot.



I could just delete the rest of the linedefs connected to this unclosed sector, but then it would spread throughout every sector connected to it(which would lead me to redoing just about everything in my map.) I wanted to know if there was a way to fix this problem without redoing everything.

Did you replace the missing textures BEFORE posting that?

If it's just an unclosed sector, check the lindefs around the sector and make sure the front side and back side have the same sector number as the sector the front and back sides are facing. I can't explain it very well so I made an example unclosed sector and took a few screenshots fixing it.



Sector 1 is an unclosed sector (where I selected doesn't really show it, but it is), and sector 0 is around that sector. Linedef 4 is the line that makes the sector an unclosed sector.



Linedef 4 is making it an unclosed sector because the front side is tagged to sector 0, instead of sector 1. To fix the unclosed sector, change the front side back to sector 1 (because the front side's facing sector 1).

What you said was a lot of help, and I managed to fix it, thanks.