function_get_address (2024 edition)

Supported versions: GameMaker Studio 2.3.x, GameMaker 2022+

For older GameMaker versions, check out the 2019 edition.

What is this

This is an example of how to get pointers to GameMaker's built-in functions and pass them to native extensions.

This enables you to call built-in functions (or user-defined ones!) from native code, which can be used to create faster and more convenient extensions - see Apollo for an example.

How this works

ptr(method(undefined, a_built_in_function)) gives you a pointer to a method-struct, which, among other things, contains a pointer to the function itself.

There is currently no way to get a function pointer from these using YYRunnerInterface, but we can figure out the offset ourselves by comparing layout of two method structs pointing at the same built-in function.

How to use it

• Import the extension
• Call function_get_address_init()
• You can now call function_get_address (e.g. function_get_address(show_debug_message)) and alike to get pointers to built-in functions.

For use in your own extensions, you can either bundle the function_get_address extension with yours (it's 4KB!), or borrow the initializer code.

function_get_address_demo

This small example DLL shows how to call built-in functions, as well as calling user-defined scripts.

Limitations

YYRunnerInterface is currently (Feb 2024) only implemented on desktop platforms, which means that using this on mobile/consoles requires additional legwork even though the core trick remains functional.

Meta

Author: YellowAfterlife
License: MIT