Unity Smart Merge Tool

Unity comes with a powerful tool to handle merge conflicts in Unity. It's hidden and there's almost no information regarding it for newcomers.

This is a quick guide on how to configure Git and Unity so that you can have multiple persons working in the same scene.

Software installed

• Unity
• Git and Git LFS
• WinMerge

Unity Project set up

Note: these steps need to be done whenever you make a new Unity Project

1. Open the project in Unity and in the top bar, select Edit and then Project Settings > Editor

2. Change the Version Control mode to Visible Meta Files and the Asset Serialization mode to Force Text

   

3. (Optional) In the top bar, select Edit and then Project Settings > Player

4. Change the Scripting Runtime Version to .NET 4.x Equivalent and the API Compatibility Level to .Net Standard 2.0

   

Git set up

Note: these steps need to be done whenever you make a new Unity Project

1. Initialize repository $ git init
2. Initialize Git LFS $ git lfs install
3. (Optional) Add these files to the root folder:

• .gitignore - Indicates files to ignore, that won't be saved to the repository

• .gitattributes - Indicates attributes of the project, and which files to save in Git LFS mode (images, sounds, textures, etc).

4. Go to the project folder and make sure you can see the hidden files and folders, go to the .git folder and open the config file with a text editor of your choice.
5. Add the following lines to the file and save it: (You will probably need to replace the path to the merge tool in line 5)

   [merge]
    tool = unityyamlmerge
   [mergetool "unityyamlmerge"]
    trustExitCode = false
    cmd = 'C:\\Program Files\\Unity\\Hub\\Editor\\2018.3.0f2\\Editor\\Data\\Tools\\UnityYAMLMerge.exe' merge -p "$BASE" "$REMOTE" "$LOCAL" "$MERGED"
   [mergetool]
    keepBackup = false
   

Unity Smart Merge set up

1. Download a fallback merge tool of your preference. The only one that works for me personally is WinMerge, but if you already have some other skip this step.

2. Go to the Unity installation folder in Editor/Data/Tools and find the mergespecfile.txt and open the file with administrator mode, the path may vary according to the OS and if you have Unity Hub installed.

   If you have Unity Hub installed the file it's probably in C:\Program Files\Unity\Hub\Editor\201x.x.xfx\Editor\Data\Tools\mergespecfile.txt, if you don't it's probably in C:\Program Files\Unity\Editor\Data\Tools\mergespecfile.txt-

   This file tells you how to set up the merge tool for various third party applications. The only uncommented lines are unity use ..... and prefab use ....., these lines indicate the calls to the fallback tool to solve scene (unity use) and prefab (prefab use) conflicts when it needs manual input on how it should solve it.

3. Replace these 2 lines:

   unity use "%programs%\YouFallbackMergeToolForScenesHere.exe" "%l" "%r" "%b" "%d"
   prefab use "%programs%\YouFallbackMergeToolForPrefabsHere.exe" "%l" "%r" "%b" "%d"
   

   with

   unity use "C:\Program Files (x86)\WinMerge\WinMergeU.exe" "%r" "%b" "%l" -o "%d" --auto-merge
   prefab use "C:\Program Files (x86)\WinMerge\WinMergeU.exe" "%r" "%b" "%l" -o "%d" --auto-merge
   * use "C:\Program Files (x86)\WinMerge\WinMergeU.exe" "%r" "%b" "%l" -o "%d" --auto-merge
   

   You may need to change the path if you prefer another software or isntall it in another directory.

How to Use

When trying to merge or rebase your project and a conflict appears, like this

Auto-merging Assets/Scenes/Scene.unity
CONFLICT (content): Merge conflict in Assets/Scenes/Scene.unity
Automatic merge failed; fix conflicts and then commit the result.

instead of manually fixing it, you just type:

$ git mergetool

The tool will then resolve the conflicts for you automatically, if there is any conflict that requires input in order to be fixed, the fallback tool (WinMerge) will open, and then you will have to choose the right option. If you don't have a fallback tool, you'll just get a message stating this, but you'll still be able to resolve the conflitcs in your editor.

Save and close the fallback tool. Then you simply need to run git add . in order to add the changes made in git, and then git commit -m 'Your message here' to complete the merge and save it.

Resources

Unity Manual - Smart Merge
Smart Merge not working
Anacat - Unity Mergetool
Videojogos - Unity Git