Quick start

This walks through the order from installing to your first Behaviour running in a world.

Requirements

You need a Unity 2022.3 project with the VRChat Worlds SDK (Udon) installed. In a project without the SDK, the runtime APIs can’t be resolved, so nothing works.

1. Installing the package

Step	What to do
1	Add https://zz-roba.github.io/tsukimi-vpm/index.json as a VPM listing
2	Pick TsukimiSharp(T#) from the package list and install it

VCC and ALCOM follow the same steps.

Installing from the distributed file

The distributed file is wrapped in a zip. Extract it, and add the .tgz that comes out through Add package from tarball in Unity’s Package Manager (Window ＞ Package Manager). This button is in Unity’s Package Manager; VCC and ALCOM don’t have it.

Installing brings in the MCP server used from AI clients and the instructions for the AI to read, alongside the compiler and the editor extension. The steps on this page involve no configuration. Only when you use the MCP server does the separate setup on MCP server apply.

2. Your first script

Right-click in the Project view and pick T# Script under Create.

A window opens for naming it. Once you decide the name, one empty behaviour and its matching program asset are created at the same time. The two are treated as a pair, so don’t delete or rename just one of them.

The save location is a folder inside Assets (saving directly under Assets is cancelled, because the dedicated assembly definition can’t be placed there).

Files created alongside it

When there is no assembly definition anywhere above that folder, an assembly definition and IsExternalInit.cs are created in the same folder. Both are needed to use the newer syntax. In a folder that already has .cs files, you are asked whether it may be split.

The file you get reads as plain C#. It holds one class that inherits Tsukimi.TsukimiBehaviour, and that’s where you write the events the runtime calls.

3. Saving and compiling

Saving runs the compile at that point. If it passes, the result appears on the program asset. The instruction count, the number of externs, and the generated Udon assembly can all be read in the same place.

The run is also reported in the Console.

Types in other .cs files

A Behaviour’s program can refer to the types written in the .cs files in this range.

• The folder that holds the Behaviour’s .cs
• The folders under it

What a .cs in the range holds	How it enters the program
Only helper types (struct, enum, static classes and so on)	The type definitions are built into this program
Further partial parts of the same Behaviour (including those that do not write the base class)	They become part of this program. Files named Name.Tests.cs are excluded (Testing)
Another concrete Behaviour	It can be referred to as a type (declare public Lamp lamp; and call lamp.Toggle()). Its method bodies do not become part of this program
A type in a folder outside the range	It is a CS0246 error. The error names the file that declares the type and says that the file is outside the range

What gets recompiled

Saving a .cs makes every program whose range includes it a candidate for recompiling. If the previous compile succeeded, a program whose only changes are the following is not recompiled.

• Comments and whitespace
• The method bodies of another Behaviour in the range (except static methods, generic methods, and Behaviours that are inherited from or declared partial)

Change	Programs whose range includes it
Fields, method signatures, attributes	Recompiled
Running TsukimiCode > Compile All Tsukimi Programs	All are recompiled

How errors appear

When you have written something that doesn’t compile, a Japanese error with a position appears. To look a number up, see Error.

4. Placing it in a scene

Drag the script you created onto a GameObject in the scene. A UdonBehaviour is attached, and the program asset is bound to it. The values visible in the Inspector come straight from the field declarations.

Alternatively, you can add one by choosing Udon Behaviour from Add Component and specifying the program asset.

5. Checking that it runs

Press Play to check it inside Unity. You can also upload the world and check it there.

Files placed in the project

Installing the package places one Assets/TsukimiCode/IsExternalInit.cs. It is the type C# requires in order to write record and init, and Unity doesn’t have it. It isn’t placed in a project that already has the same type (that would be a duplicate definition).

It is placed once, the first time. If you delete it, it is not created again.

How to restore it

Deleting this file stops scripts that use record or init from compiling (定義済みの型 System.Runtime.CompilerServices.IsExternalInit が定義されていません). To put it back, place a .cs file with the following content inside Assets.

namespace System.Runtime.CompilerServices
{
    internal static class IsExternalInit
    {
    }
}

It can go anywhere under Assets, with two things to watch for.

• Don’t put it under Assets/Plugins. That is a separate assembly, so it won’t apply.
• If you create an assembly definition (.asmdef) and put your scripts inside it, that assembly needs the same type too. The type is needed per assembly. When an assembly definition was created along with your T# Script, it is already in the same folder and nothing needs doing.

Bundled samples

Press Import Samples under the TsukimiCode menu and they are imported into Assets. One sample is imported, containing two scenes. Open one and press Play.

Scene	Contents
Showcase	A row of them, each showing one way to write something
FloorGlow	The floor glows under the player’s feet. A single one lifted out on its own