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Automatic .proto files compilation in Unity project to C# as you edit them.
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5argon Merge pull request #6 from assert-not-singularity/master
Fix use of SettingsScope enum to avoid CS0117
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ProtobufUnityCompiler.cs Added package.json to support UPM, updated README Jul 29, 2018
package.json Make the pref works with Unity 2018.3+, added asmdef. Oct 11, 2018


Sirawat Pitaksarit / 5argon - Exceed7 Experiments


Do you want to integrate protobuf as a data class, game saves, message to the server, etc. in your game? Now you can put those .proto files directly in the project, work on it, and have this generate the classes for you.


  1. When you write a .proto file normally you need to use the protoc command line to generate C# classes. This plugin automatically find all your .proto files in your Unity project, generate them all, and output respective class file at the same place as the .proto file. It automatically regenerate when you change any .proto file.

If there is an error the plugin will report via the Console.

  1. Now, your generated class will contains using Google.Protobuf. Which means you must have Google.Protobuf.dll in your Unity project.


  • (1/12/2017) Now include paths is not only the folder of the file that is being compiled, but all folders that has a .proto file in your project. Proto includes on the .proto file's header does not support ., .. etc. so this way you can use an unqualified name to reference any .proto file in your Unity project. Split assembly is available in 2017.3 and it uses folder hierarchy. This can help you split up your proto files.
  • (29/07/2018) There is a package.json so you could use Unity Package Manager now. Google for how to do it locally and according to Unity Berlin talk we will be able to use UPM with GitHub address directly later. I am preparing for that.

Problem with iOS + IL2CPP

Now that you can't use mono backend anymore on iOS, there is a problem that IL2CPP is not supporting System.Reflection.Emit. Basically you should avoid anything that will trigger reflection as much as possible.

Luckily the most of core funtions does not use reflection. The most likely you will trigger reflection is protobufClassInstance.ToString() (Or attempting to Debug.Log any of the protobuf instance.) It will then use reflection to scan figure out what is the structure of all the data just to print out pretty JSON-formatted string. To alleviate this you might override ToString so that it pull the data out to make a string directly from generated class file's field. I am not sure of other functions that might trigger reflection.

You should see the discussion in this and this thread. The gist of it is Unity failed to preserve some information needed for the reflection and it cause the reflection to fail at runtime.

And lastly the latest protobuf (3.6.0) has something related to this issue. Please see So it is recommended to get the latest version!


  1. Put files in your Unity project
  2. You can access the settings in Preferences > Protobuf. Here you need to put a path to your protoc executable.


  1. As soon as you import/reimport/modify (but not moving) .proto file in your project, it will compile only that file to the same location as the file. If you want to temporary stop this there is a checkbox in the settings, then you can manually push the button in there if you like. Note that deleting .proto file will not remove its generated class.


Requires protoc. This plugin does not include protoc command and will try to run it from your command line (via .NET System.Diagnostics.Process.Start). Please see and install it. Confirm with protoc --version in your command prompt/terminal.

Some notes about Protocol Buffer

For complete understanding I suggest you visit Google's document but here are some gotchas you might want to know before starting.

  • Use CamelCase (with an initial capital) for message names – for example, SongServerRequest. Use underscore_separated_names for field names – for example, song_name.
  • By default of C# protoc, the underscore_names will become PascalCase and camelCase in the generated code.
  • .proto file name matters and Google suggests you use underscore_names.proto. It will become the output file name in PascalCase. (Does not related to the file's content or the message definition inside at all.)
  • Field index 1 to 15 has the lowest storage overhead so put fields that likely to occur often in this range.
  • The generated C# class will has sealed partial.
  • You cannot use enum as map's key.
  • It's not int but int32. And this data type is not efficient for negative number. (In that case use sint32)


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Works on macOS. Untested on Windows/Linux since I am not developing games in those environments. If you encountered any problems please use the Issue section or send a PR if you manages to fix it. Thank you.


As this includes protobuf you need to follow Google's license here :

For my own Unity code the license is MIT without requiring any attributions. (The part where it says "The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software." is not required.) You are welcome to include it if you want.

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