Version: 2020.3
  • C#


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public void OnImportAsset(AssetImporters.AssetImportContext ctx);


ctx This argument contains all the contextual information needed to process the import event and is also used by the custom importer to store the resulting Unity Asset.


This method must by overriden by the derived class and is called by the Asset pipeline to import files.

using UnityEngine;
using UnityEditor.AssetImporters;
using System.IO;

[ScriptedImporter(1, "cube")] public class CubeImporter : ScriptedImporter { public float m_Scale = 1;

public override void OnImportAsset(AssetImportContext ctx) { var cube = GameObject.CreatePrimitive(PrimitiveType.Cube); var position = JsonUtility.FromJson<Vector3>(File.ReadAllText(ctx.assetPath));

cube.transform.position = position; cube.transform.localScale = new Vector3(m_Scale, m_Scale, m_Scale);

// 'cube' is a a GameObject and will be automatically converted into a Prefab // (Only the 'Main Asset' is elligible to become a Prefab.) ctx.AddObjectToAsset("main obj", cube); ctx.SetMainObject(cube);

var material = new Material(Shader.Find("Standard")); ctx.DependsOnCustomDependency("StandardShaderDependencyHash");

material.color =;

// Assets must be assigned a unique identifier string consistent across imports ctx.AddObjectToAsset("my Material", material);

// Assets that are not passed into the context as import outputs must be destroyed var tempMesh = new Mesh(); DestroyImmediate(tempMesh); } }

To use the Shader.Find() function in the above example, you need to write a custom dependency for the shader you want to find and regularly update it. This prevents the Shader.Find() function from bypassing other means of dependency checking. The below code is an example of how you might write a custom dependency for this purpose.

using UnityEditor;
using UnityEngine;

static class ShaderDependencyUpdater { [InitializeOnLoadMethod] static void ShaderDependencyInit() { EditorApplication.update += ShaderDependencyUpdate; } static void ShaderDependencyUpdate() { var shader = Shader.Find("Standard"); AssetDatabase.TryGetGUIDAndLocalFileIdentifier(shader, out var guid, out long id); var hash = new Hash128(); hash.Append(guid); hash.Append(id); AssetDatabase.RegisterCustomDependency("StandardShaderDependencyHash", hash); } }