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MinecraftRunAPI is a class library created in C# (usable in all .NET languages) in order to facilitate the launching of Minecraft from your applications or custom launchers. It is really simple to use.

This needs some preparations before being usable.

This API requires the JSON.NET library to run properly. In fact, it will not work if this API is missing, since it is used to retrieve the datas in the .JSON file.

Before you can use MinecraftRunAPI to launch Minecraft, you will have to get the natives corresponding to the version you want to launch. These natives are automatically downloaded by the official launcher at runtime, and deleted after Minecraft is closed. Please follow the bellow steps if you don't know how to retrieve the natives.

You can just copy the natives folder when Minecraft run, in going to C:\Users\<You>\AppData\Roaming\.minecraft\versions\<Your version> and copying the folder named <some-random-numbers>-natives where you want (personnaly, I created a folder at C:\Users\<You>\AppData\Roaming\.minecraft\natives and put all my natives in there). The inconveniant is that it will work only for you, and not your users. You can make your launcher downloading thoses natives, for example.

The second way to get the natives is to download them directly from the link situated at the end of the <version>.json file located in C:\Users\<you>\AppData\Roaming\.minecraft\versions\<version>\. You can use, for example, the JSON.NET library to parse this file. Maybe I'll make MinecraftRunAPI automatically retrieve those files, later.

Once these steps are completed, you can easily get the command line that will be used to launcher Minecraft:

CommandLine MinecraftCommand = new CommandLine(
  @"1.9",
  new UserCredentials("<UUID>", "<Username>", "<AccessToken>"),
  @"C:\Users\<You>\AppData\Roaming\.minecraft\natives\<version>-natives"
  );

The first argument is the version of Minecraft you want to launch, the second is the UserCredentials object which contains the user's credentials (it is compatible with MojangAPI). The third argument is the path to the natives folder. This constructor can be overloaded to modify the arguments, like the heap min, initial and max size of the JVM, the game path, or the version type.

Now you have prepared the command, you can either retrieve it or directly launch Minecraft via the CommandLine object.

Console.WriteLine(MinecraftCommand.GetCommandLine(true));

The parameter of the method GetCommandLine() determine if the java executable path will be set before the command.

MinecraftCommand.Run();

CommandLine.Run() has now three constructors.

public void Run()

This one will simply run the command line and show the output on the console.

public void Run(StreamWriter stream)

This one will run the command line and show the output on the console and on the StreamWriter passed as an argument. Note that you can pass an empty stream (null). In this case, it works as the first constructor.

public void Run(StreamWriter stream, bool log)

By default, the second argument, log, is set to true. If false, the output will not be redirected to the console.

The UserCredentials class is compatible with MojangAPI. It means you can use the requests of MojangAPI to run Minecraft through MinecraftRunAPI.

// Creating the auth request
Request authRequest = new Request(Request.Method.POST, URL.AUTHENTICATION.SIGN_IN);
string raw = authRequest.Execute(Header.Authentication.Signin("<you>", "<your password>"));
AuthenticationResponse authResponse = new AuthenticationResponse(raw);

// Creating the uuid request
Request uuidRequest = new Request(Request.Method.GET, URL.UUID_BY_NAME, authResponse.GetResponse.PlayerName);
raw = uuidRequest.Execute();
UuiByNameResponse uuidResponse = new UuiByNameResponse(raw);

// Creating the MinecraftLaunching credentials
UserCredentials credentials = new UserCredentials(
    (MinecraftLaunching.Structures.AuthenticationResponse)authResponse.GetResponse,
    (MinecraftLaunching.Structures.UuidByNameResponse)uuidResponse.GetResponse);
    
CommandLine MinecraftCommand = new CommandLine(
@"1.9",
new UserCredentials(
    (MinecraftLaunching.Structures.AuthenticationResponse)authResponse.GetResponse,
    (MinecraftLaunching.Structures.UuidByNameResponse)uuidResponse.GetResponse),
@"C:\Users\<you>\AppData\Roaming\.minecraft\natives\1.9-natives"
);

This example will run Minecraft 1.9 if the folder C:\Users\<you>\AppData\Roaming\.minecraft\natives\1.9-natives contains the 1.9 natives files.

• Add a way to redirect the console stream
• Make MinecraftRunAPI download the natives

If you spotted an issue, please start a new ticket. I will answer as soon as possible. Thank you.