CLΔ Sync Plugin

Enables list/variable synchronization between players for CLΔ Core.

CLΔ Sync is a powerful plugin that allows you to synchronize Scratch variables and lists between different players in real-time without needing any additional code. It’s built to be highly efficient, de-duplicating redundant data and batching events to keep your project running fast with minimal network traffic.

What is a Tag?

A Tag is the most important concept in this plugin. Think of it as a public, network-safe nickname or a mailing label for your variable.

• The Problem: Your “my variable” on “Sprite1” is not the same as your friend’s “my variable” on their “Sprite1.” They are two different variables with different internal IDs.
• The Solution: You both agree on a unique, shared “tag,” like "player_1_x_position".
  • You (Player 1) link your variable to the tag "player_1_x_position".
  • Your Friend (Player 2) links their variable to the exact same tag.

Now, when you update your variable, the plugin sends a message saying: “Hey everyone, the variable tagged "player_1_x_position" just changed to 120.” Your friend’s plugin, which is listening for that tag, receives the message and automatically updates their bound variable to 120.

Tags must be unique for each variable or list you want to sync.

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Getting Started

CLΔ Core is required for the sync plugin to work. Make sure you load it first before loading CLΔ Sync.

Let’s sync a “global variable” (on the Stage) between two players.

Player A (Sender)

1. Go to the Stage and create a new variable named (Player A X).
2. Drag out this block and set it up like this:
   • [enable] broadcast of [global variable] [Player A X] in channel [default] and assign it as tag [p1_x]

Now, any time you change (Player A X), its new value is broadcast to everyone in the “default” channel with the tag “p1_x”.

Player B (Receiver)

1. Go to the Stage and create a new variable named (Player A's X).
2. Drag out the exact same block. The only difference is your local variable name.
   • [enable] broadcast of [global variable] [Player A’s X] in channel [default] and assign it as tag [p1_x]

Result

Now, whenever Player A changes their (Player A X) variable, Player B will instantly see their (Player A's X) variable update to match. You have successfully synced a variable!

To stop syncing, simply run the same block with [disable] selected. This will un-link the variable and restore it to a normal, non-networked state.

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How It Works

• Change Detection - The plugin wraps your variable in a special “proxy” object that instantly detects when its value changes.
• De-duplication - If you set a variable to the same value it already has (e.g., set [my_var v] to (10) when it’s already 10), the plugin knows not to send an unnecessary network message. This dramatically reduces network spam.
• Event Batching - Instead of sending a message for every single change (which can be 30 times a second!), the plugin collects all unique changes that happen in a small time window (e.g., 100ms) and sends them as a single, efficient packet.
• Idle Detection - If nothing changes for more than a second, the sync engine goes to sleep to save resources, waking up instantly when a new change occurs.

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Reference

Sync Commands

Use these blocks to start or stop syncing a variable.

[MODE] broadcast of [TYPE] [VAR] in channel [CHANNEL] and assign it as tag [TAG] This is the main block. It links a local variable/list to a network tag and sends any changes to everyone in that channel.

• MODE: enable or disable.
• TYPE: The scope and type of your variable (e.g., global variable, local list).
• VAR: The name of your variable or list.
• CHANNEL: The “room” to send the data to.
• TAG: The unique network nickname for this variable.

[MODE] multicast of [TYPE] [VAR] in channel [CHANNEL] with peers in [MCAST] list [LIST] and assign it as tag [TAG] Same as broadcast, but it only sends changes to the peers whose usernames are in your specified [LIST]. Useful for teams. The value of [LIST] can be changed during runtime, and accordingly, the peers you multicast to.

[MODE] unicast of [TYPE] [VAR] with [PEER] in channel [CHANNEL] and assign it as tag [TAG] Same as broadcast, but it only sends changes to a single peer, specified by their username. Useful for direct messages or trading.

Sync Tags (Reporters)

Use these blocks to check the status of your tags.

is tag [TAG] in use? Returns true if you have already used this tag to sync a variable/list.

tag [TAG] currently bound to Reports what a tag is linked to on your machine (e.g., “global variable: Player A X”).

is tag [TAG] broadcasting in channel [CHANNEL]? Returns true if the tag is currently set to broadcast mode in that specific channel.

is tag [TAG] multicasting… Returns true if the tag is currently set to multicast mode with that specific list.

is tag [TAG] unicasting… Returns true if the tag is currently set to unicast mode with that specific peer.

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