Scratch Compiler

A monorepo for compiling Scratch 3 (.sb3) projects into standalone, high-performance web applications using TypeScript and Konva.js.

Overview

The Scratch Compiler transforms Scratch project files into a directory containing:

• index.html: A clean entry point for the web application.
• assets/: All costumes and sounds extracted from the original .sb3 file.
• src/main.js: A generated JavaScript file that initializes the project state.
• src/engine.min.js: A lightweight runtime that handles rendering and execution.

Project Structure

This project is managed as a PNPM workspace:

• packages/cli: The command-line interface used to compile .sb3 files.
  • Extracts assets and project.json.
  • Generates the main.js loader.
  • Packages the static web template.
• packages/client: The browser runtime (engine).
  • Built with Konva.js for hardware-accelerated 2D rendering.
  • Defines the Stage and Sprite primitives.
• packages/types: Shared TypeScript definitions for the Scratch 3.0 file format.

Current State

The project is currently in early development.

Supported Features

• Extraction of .sb3 archives.
• Automated asset extraction (Images, SVGs, Audio).
• Migration of project structure (Stage and Sprite initial states).
• Generation of a readable main.js file.
• Basic rendering engine using Konva.js.
• Basic events (flag, click, keypress, broadcast).
• Monorepo setup with optimized build pipeline (esbuild + TSC).

In Progress / Roadmap

• Block execution engine (interpreting Scratch scripts).
• Support for Scratch variables and lists.
• Sound playback integration.
• Advanced graphic effects (ghost, color, etc.).
• Pen extension support.

Getting Started

Prerequisites

• Node.js (v20 or newer)
• PNPM

Installation

pnpm install

Building

Build the entire workspace:

pnpm run build

Compiling a Scratch Project

To compile a .sb3 file:

pnpm run cli:start --file path/to/your/project.sb3 --output ./dist-web

License

MIT