Dynamically creating a MeshLibrary - CollisionPolygon not working

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:bust_in_silhouette: Asked By dee

Hi,

I’m trying to create a MeshLibrary programmatically. However, when I’m trying to add a CollisionPolygon, it either falls back to a BoxShape, or it never actually gets added (GetItemShape returns an empty array).

So far, I’ve tried to see how the editor solves this by looking at the MeshLibrary import:

And I’ve looked into what the MeshLibrary SetItemShapes method actually expects:

What I’ve learned so far, is that CollisionPolygon seems to be an editor tool, and it seems like I need to pass some array of ShapeData (which is a struct of Shape and Transform) to SetItemShapes instead.

However, how do I solve this? Can I even get access to Shape types through C#?

This is my code so far:

// Create MeshLibrary
var library = new MeshLibrary();
library.CreateItem(0);

// Load resource
var resource = ResourceLoader.Load("res://Objects/Blocks/Stairs.tscn") as PackedScene;
var instance = resource.Instance() as MeshInstance;

// Set mesh
library.SetItemMesh(0, instance.Mesh);

// Get StaticBody and CollisionPolygon
var staticBody = instance.GetChild(0) as StaticBody;
var shape = staticBody.GetChild(0) as CollisionPolygon;

var data = new Array();

data.Add(shape);
data.Add(instance.Transform);

library.SetItemShapes(0, data);
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:bust_in_silhouette: Reply From: dee

I figured it out. It seems that CollisionPolygon is specific for the editor. I used CollisionShapes (ConvexPolygonShape), and fetched the Shape instead:

var library = new MeshLibrary();
library.CreateItem(0);

var resource = ResourceLoader.Load("res://Objects/Blocks/Stairs.tscn") as PackedScene;
var instance = resource.Instance() as MeshInstance;

library.SetItemMesh(0, instance.Mesh);

var staticBody = instance.GetChild(0) as StaticBody;

var data = new Array();

foreach(var child in staticBody.GetChildren())
{
    if((child is CollisionShape shape)) 
    {
        data.Add(shape.Shape);
        data.Add(shape.Transform);
    }
}

library.SetItemShapes(0, data);