This is a port of the Doom map editor GZDoomBuilder from https://sourceforge.net/p/doombuilder/code/HEAD/tree/.
The master branch of this repo is a mirror of the GZDoomBuilder branch from the svn repo. The develop branch is the up-to-date version of the Meridian 59 port.
The editor can edit Meridian 59 rooms in 2D and 3D format. Most GZDoomBuilder special features work (e.g. stair building, some 3D room manipulations such as texture dragging). The old Meridian 59 roomeditor is included as a node compiler, and is called when saving a room.
You can build the editor from source by forking the repo, opening builder.sln in Visual Studio 2013 and building all projects, then running /Build/Builder.exe.
Alternatively, you can download an up-to-date precompiled version here. Note that this requires 7Zip to open.
To display textures in maps, you will need to add the Meridian 59 client's resource
folder so GZDoomBuilder can load the textures. Open up GZDoomBuilder but do not
load a map. Select Tools from the toolbar, then select Game Configuration. From
the dialog box, select Meridian 59 (roo v15 format) from the list, then click
Add Resource. Choose the From Directory tab and add in the Meridian 59 client's
resource directory.
If you installed Meridian 59 from the server 105 installer, this directory
will be at C:\Users\username\AppData\Local\Open Meridian\Meridian 105\resource
or if you used the Open Meridian patcher, it will be at C:\Program Files\Open Meridian\Meridian 105\resource.
Make sure the checkboxes for Load images in directory root as textures and
Load images in directory root as flats are ticked.
The most up-to-date rooms are in the develop branch of the server 105 GitHub repository so if editing existing rooms it is best to start from this room set.
The GZDoomBuilder port should still be able to create/modify Doom and Doom-related maps, but porting maps from Doom to Meridian 59 format has not been attempted yet.
The .roo files generated by the editor work on server 105 and server 112 versions of Meridian 59.
Please file any issues you find while using this program on the GitHub Issues page.