AssetImportContext.DependsOnArtifact

Parameters

Description

Setup artifact dependency to an asset.

An artifact dependency is a dependency where an Asset depends on the import result (known as an artifact) of another Asset. If you change an Asset that has been marked as a dependency, all Assets which depend on it will also get reimported (after the dependency has been imported).

If you specify an asset as a dependency that doesn't exist or hasn't yet been imported, the dependency is registered as an un-imported asset. When the asset is later imported, Unity reimports all assets which depend on it. When you set up an artifact dependency, use GUIDs rather than paths where possible because the GUID remains consistent even when the asset is moved or renamed.

using UnityEngine;
using UnityEditor;
using UnityEditor.AssetImporters;

class TextureInfo : ScriptableObject
{
    public int height;
}

[ScriptedImporter(1, "cube")]
public class CubeWithTextureImporter : ScriptedImporter
{
    public override void OnImportAsset(AssetImportContext ctx)
    {
        var assetDependency = "Assets/MyTexture.png";

        ctx.DependsOnArtifact(assetDependency);

        var texture = AssetDatabase.LoadAssetAtPath<Texture>(assetDependency);

        if (texture != null)
        {
            var textureInfo = ScriptableObject.CreateInstance<TextureInfo>();
            textureInfo.height = texture.height;
            ctx.AddObjectToAsset("TextureInfo", textureInfo);
        }
    }
}

You can declare artifact dependencies using either LazyLoadReference<T0> or regular Object references. Use AssetDatabase.TryGetGUIDAndLocalFileIdentifier to obtain the GUID from either type of reference.

LazyLoadReference<T0> is preferred for importer settings because it does not load the referenced asset when the importer is deserialized. Regular Object references can also be used, but they trigger loading the referenced asset immediately upon deserialization.

In both cases, the referenced asset may not yet have been imported, so always validate references.

using UnityEditor;
using UnityEditor.AssetImporters;
using UnityEngine;

public class MyImporter : ScriptedImporter
{
    public LazyLoadReference<AnimationClip> sourceClip;
    public LazyLoadReference<GameObject> sourcePrefab;
    public Texture2D sourceTexture;

    public override void OnImportAsset(AssetImportContext ctx)
    {
        // Declare artifact dependencies using LazyLoadReference
        if (AssetDatabase.TryGetGUIDAndLocalFileIdentifier(sourceClip.entityId, out string clipGuid, out long _))
        {
            if (GUID.TryParse(clipGuid, out GUID clipArtifactGuid))
            {
                ctx.DependsOnArtifact(clipArtifactGuid);
            }
        }

        if (AssetDatabase.TryGetGUIDAndLocalFileIdentifier(sourcePrefab.entityId, out string prefabGuid, out long _))
        {
            if (GUID.TryParse(prefabGuid, out GUID prefabArtifactGuid))
            {
                ctx.DependsOnArtifact(prefabArtifactGuid);
            }
        }

        // Declare artifact dependency using a regular Object reference
        if (!ReferenceEquals(sourceTexture, null))
        {
            if (AssetDatabase.TryGetGUIDAndLocalFileIdentifier(sourceTexture, out string textureGuid, out long _))
            {
                if (GUID.TryParse(textureGuid, out GUID textureArtifactGuid))
                {
                    ctx.DependsOnArtifact(textureArtifactGuid);
                }
            }
        }

        if (sourceClip.asset != null && sourcePrefab.asset != null && sourceTexture != null)
        {
            // Do import stuff..
        }
    }
}