How do I use gd internal packages?

[nii236]

In particular, I'm trying to call SurfaceTool.Instance.Begin(), but the signature is func (self Instance) Begin(primitive gdclass.MeshPrimitiveType).

Package gdclass is an internal package, so I can not call this function with the correct argument!

Broken code as follows:

type SurfaceNet struct {
	classdb.Extension[SurfaceNet, MeshInstance3D.Instance]
	SurfaceTool SurfaceTool.Instance
	Noise       Noise.Instance
}

func (s *SurfaceNet) Ready() {
	s.SurfaceTool = SurfaceTool.New()
	// 	gd: surfaceTool.begin(Mesh.PRIMITIVE_TRIANGLES);
	s.SurfaceTool.Begin(gdclass.MeshPrimitiveType(Mesh.PRIMITIVE_TRIANGLES))

	BLUE_D := Color.Hex(("#29ABCA"))
	s.SurfaceTool.SetColor(BLUE_D)
	s.SurfaceTool.SetSmoothGroup(-1)
	s.CreateSurfaceMesh(16)
	s.SurfaceTool.GenerateNormals()
	// result := s.SurfaceTool.Commit()

	// 	mesh = surfaceTool.commit();
	// s.Super().SetMesh(result)
}

[nii236]

I've solved this by using the underlying int64 type.

// Internal type is int64
type MeshPrimitiveType int64

// Just use an int64
// From https://docs.godotengine.org/en/4.0/classes/class_mesh.html#enum-mesh-primitivetype
const PRIMITIVE_TRIANGLES = 3
s.SurfaceTool.Begin(PRIMITIVE_TRIANGLES)

[Splizard]

@nii236 I really appreciate all of the dicussions you've started and issues you have finding. It really helps the project!

In this case, the Mesh classdb package aliases this type:

type PrimitiveType = gdclass.MeshPrimitiveType //gd:Mesh.PrimitiveType

const (
	/*Render array as points (one vertex equals one point).*/
	PrimitivePoints PrimitiveType = 0
	/*Render array as lines (every two vertices a line is created).*/
	PrimitiveLines PrimitiveType = 1
	/*Render array as line strip.*/
	PrimitiveLineStrip PrimitiveType = 2
	/*Render array as triangles (every three vertices a triangle is created).*/
	PrimitiveTriangles PrimitiveType = 3
	/*Render array as triangle strips.*/
	PrimitiveTriangleStrip PrimitiveType = 4
)

You can use these constants directly without creating your own constant declarations.

s.SurfaceTool.Begin(Mesh.PrimitiveTriangles)

I am aware this isn't particularly easy to find and the godot documentation imported as-is references the enum values in all-upper-case. The use of the internalgdclass declarations only serves to prevent circular dependencies, as without it, all of the classdb packages references each-other and cannot be compiled. So they all refer to shared internal types that are exported by the respective class packages.

[nii236]

Haha I feel kinda bad asking all these questions and getting help for free!

That said it also kinda shows that no one has really tried using gd in anger yet.

Anyway cool that you're already using aliases, new Go feature.

Thanks for your help yet again. Soon I'll have a game running...

[Splizard]

Lucky you are jumping in now, before the 2025 overhaul everything was being dumped into a single gd package, the pkg.go.dev page was unhelpful and everything took so long to recompile. I'm very happy with how things are coming together now. Once the issues are ironed, due to all the unique qualities of Go (with a simple yet strict type system, build times and tooling, etc), this project has a good chance to become one of most convenient ways to leverage all of the amazing technology behind Godot!

Would love to see anything you're building, let us know in the discussions when you have something to share.