Creating a Part

This guide will walk you through creating a custom part and adding it to the StellarDrive build menu.

A custom part requires:

• A model prefab
• A thumbnail
• Basic properties
• Optional building costs

Parts are created using a PartDefinition and registered through the API. The API automatically adds registered parts to StellarDrive's build menu.

Loading Assets

Before creating a part, you need to load the assets used by the part.

The StellarModdingAPI provides AssetCollection for loading assets from Unity AssetBundles. Mark each asset name as a constant with [AssetKey], then load them all at once in LoadAssets():

public static AssetCollection? Assets { get; private set; }

[AssetKey] public const string PottedPlantKey = "PottedPlant";
[AssetKey] public const string PottedPlantThumbnailKey = "PottedPlantThumbnail";

public override void LoadAssets()
{
    Assets = AssetCollection.LoadFrom<Mod>(logger: LoggerInstance);
}

The names assigned to these [AssetKey] constants are the names of the assets that your mod will use later.

In this example:

• PottedPlant is the part's model prefab.
• PottedPlantThumbnail is the image displayed in the build menu.

For more detail on loading assets, see the AssetCollection Reference.

Creating a Part

Parts are created using PartDefinition.

A PartDefinition contains all the information required to create a part.

Example:

PartDefinition PottedPlantDefinition = new(
    Name: "Potted Plant",
    Description: "Potted plant!!!!!!!",
    Prefab: Assets.GetAsset<GameObject>(PottedPlantKey),
    Thumbnail: Assets.GetAsset<Texture2D>(PottedPlantThumbnailKey),
    PhysicalSize: Vector3.one * 0.25f,
    Mass: 1f,
    LogicalSize: Vector3.one,
    Snapping: SnappingStyle.PreciseOnAny,
    BuildingCost:
    [
        ItemCost.Of(ItemIDs.Fuel, 2)
    ]
);

The PartDefinition contains the information required to create the part, including its name, assets, physical and logical size, mass, snapping behavior, and optional building costs.

For a complete list of available properties, see:

PartDefinition Reference

Registering Parts

Parts are registered using:

Plugin.RegisterPart(PottedPlantDefinition);

Once registered, the API automatically converts the part definition into the game's internal format and adds it to StellarDrive's build menu when appropriate. No additional setup is required.

Complete Example

A complete part mod looks like this:

using MelonLoader;
using Ship.Interface.Model;
using StellarModdingAPI.Abstract;
using StellarModdingAPI.Assets;
using StellarModdingAPI.Items;
using StellarModdingAPI.Parts;
using UnityEngine;

namespace SDAPITest
{
    public static class BuildInfo
    {
        public const string Name = "Example Parts Mod";
        public const string Description = "Stellar Modding API part test mod";
        public const string Author = "Jollyname";
        public const string Company = null;
        public const string Version = "1.1.0";
        public const string DownloadLink = null;
    }

    public sealed class SDAPITest : StellarMelonMod
    {
        public static AssetCollection? Assets { get; private set; }

        [AssetKey] public const string PottedPlantKey = "PottedPlant";
        [AssetKey] public const string PottedPlantThumbnailKey = "PottedPlantThumbnail";

        public override void LoadAssets()
        {
            Assets = AssetCollection.LoadFrom<SDAPITest>(logger: LoggerInstance);
        }

        public override void OnSceneWasLoaded(int buildIndex, string sceneName)
        {
            if (buildIndex != 1) return;

            PartDefinition PottedPlantDefinition = new(
                Name: "Potted Plant",
                Description: "Potted plant!!!!!!!",
                Prefab: Assets.GetAsset<GameObject>(PottedPlantKey),
                Thumbnail: Assets.GetAsset<Texture2D>(PottedPlantThumbnailKey),
                PhysicalSize: Vector3.one * 0.25f,
                Mass: 1f,
                LogicalSize: Vector3.one,
                Snapping: SnappingStyle.PreciseOnAny,
                BuildingCost:
                [
                    ItemCost.Of(ItemIDs.Fuel, 2)
                ]
            );

            Plugin.RegisterPart(PottedPlantDefinition);
        }
    }
}

Congratulations! You have created your first custom StellarDrive part.