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extgen - GameMaker Extension Code Generator

extgen is a schema-driven code generator for GameMaker native extensions.

From a single GMIDL input file, extgen generates:

• GML bindings (plus optional runtime helpers)
• Native glue code for multiple platforms (Android / iOS / tvOS / consoles)
• A complete CMake project and presets
• Optional documentation output for downstream tooling
• NDA-compliant console configurations (user-specific SDK paths, gitignored)

The goal is a single source of truth that produces consistent, repeatable extension output across all targets.

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Quick Start

1) Initialize a project folder

extgen --init ./my-extension

This creates:

• config.json
• extgen.schema.json

2) Edit config.json

Set your GMIDL input (input), output root (root), desired targets (targets.*), and build emission (build.emitCmake).

3) Generate

extgen --config ./my-extension/config.json

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Wiki Navigation

Getting Started

• User Manual - running extgen, configuring targets, all schema options
• GMIDL Introduction - declaring functions, classes, and enums
• Implementation Workflow - recommended workflows for each target
• Console Setup - SDK configuration for Switch, PS4, and PS5

Development

• Architecture / Developer Docs - project structure, emitters, pipeline, contribution guide
• Building extgen - building from CLI, Visual Studio, or VS Code

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Key Concepts

Schema-driven configuration

config.json is validated via extgen.schema.json. If the schema validates, extgen will run.

Target-driven output

extgen is target-driven, not language-toggle driven. Enabling a target (such as Windows or iOS) automatically implies the correct underlying emitters - C++ where required, platform glue where needed.

Profiles

Profiles control what categories of output are generated:

• Full - bindings + native glue + build system
• BindingsOnly - only bindings (no native/build output)
• BuildOnly - only build system (CMake / presets)

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Need Help?

• For usage: start with the User Manual
• For contributing: start with Architecture / Developer Docs
• For building the tool: see Building extgen