[Help wanted] Convert to GDExtension.

[Faless]

Some minimal initial work to start the project of converting the module to a GDExtension.

The PR does not yet properly compile, but the build system is there, you can try by just typing scons.

The godot-cpp submodule uses this branch: godotengine/godot-cpp#819 .

Bare minimum things to implement:

• "ScriptInstanceExtension" via a GDNativeExtensionScriptInstanceInfo wrapper.
• ScriptLanguageExtension methods name (prefix with _?).
• ...

see (741f131).

I sadly don't have time to work on this right now, but I hope this PR can at least open a path to external contributions.

[derkork]

I am working on this, I already fixed about a million compile errors. Currently working on some final parts of the VisualScriptCustomNode and then there are some things left over which seem to be currently not exposed to GDExtensions:

• there seems to be no way to access the ScriptDebugger from a GDExtension (e.g. EngineDebugger::get_script_debugger) is missing.
• godot::Callable::CallError does not seem to be available for a GDExtension
• godot::MultiplayerAPI::RPCMode does not seem to be available for a GDExtension
• also ScriptServer is missing, so the extension cannot register its custom language

I am pretty new to this so I wonder how the workflow is. Should I open Tickets in godot-cpp for these or make pull requests in godot-cpp? Or is this not supposed to be exposed for GDExtensions - in which case I would need to know what is the intended replacement for these facilities.

[Faless]

godot::MultiplayerAPI::RPCMode does not seem to be available for a GDExtension

That's defined in gen/include/godot_cpp/classes/multiplayer_api.hpp

also ScriptServer is missing, so the extension cannot register its custom language

I think it can be registered via: Engine::get_singleton()->register_script_language(language);

• there seems to be no way to access the ScriptDebugger from a GDExtension (e.g. EngineDebugger::get_script_debugger) is missing.

Yeah, you can access the debugger but not the script-specific part, I don't think that's required to be able to implement the language (only for it to support debugging), but it's something that will need to look into at some point.

• godot::Callable::CallError does not seem to be available for a GDExtension

Yeah, I think those will have to be exposed to GDExtension so proper call error handling can be implemented, at least knowing if the callable call has succeeded.

Should I open Tickets in godot-cpp for these or make pull requests in godot-cpp?

Both are fine, if in doubt open a ticket or ask on the contributor chat.

[nathanfranke]

Those wanting to do this, feel free to start with this template: https://github.com/nathanfranke/gdextension

This isn't endorsed by Godot, but it is licensed as unlicense/public domain so no copyright troubles.

(P.S., can a similar template be hosted at godotengine/gdextension?)

Edit: Oh, I didn't realize this was a PR, so I guess the first step is already done 😃

[derkork]

My current progress is in https://github.com/derkork/godot-visual-script/tree/spike/extension . It is still quite a long way to go, as godot-cpp is not exposing quite a few engine functions/classes that the VisualScript module uses. I'll report these in godot-cpp one by one as I encounter them.

I don't think this is a particularly efficient way of doing things, though as every missing thing first needs to be added in godot-cpp, e.g. a PR needs to be made and reviewed and eventually the changes will be in. This can take quite a while during which I am basically blocked. In some cases I also have resorted to copy/paste from the engine source code (in hacks.cpp) to get some progress, but I will eventually need to clean this up.

I am very new to this so I probably am doing things the wrong way. If someone more experienced could give me a few tips on how this can be done more efficiently, I'd greatly appreciate it.