Asset Import Pipeline for Unity

This tool is a rule-based approach to asset postprocessors within Unity. The goal is develop re-usable processors that can be applied to assets when they are imported.

Asset Import Profiles

Asset Import Profiles are ScriptableObjects that store information about how to import assets based on a rule based path system. The rules consist of a base folder, asset types to process and processors that should execute on these assets when they are imported.

Asset Types

The asset types are Textures, Models, Audio, Videos, Fonts, Animations, Materials, Prefabs, SpriteAtlases and Other. Other can be used to match against any asset that matches a specified set of file extensions.

Path Variables

The asset import profile folder path and asset type file filters can create variables that you can use within the asset processors.

To specify a variable, wrap the variable name in {}. As an example, Assets/3DGamekit/Art/Textures/Characters/{characterName}/ will create the variable characterName with the folder name as a value when processors are run. This variable can be used when setting the asset bundle name, asset label, etc.

The variables can be forced to match a string convention such as snake case or pascal case. This can be done by adding a suffix to the variable name {characterName:\snake}.

Convention	Variable Suffix	Convention Example
No convention	:\none	The quick brown fox
Snake Case	:\snake	the_quick_brown_fox
Upper Snake Case	:\usnake	THE_QUICK_BROWN_FOX
Pascal Case	:\pascal	TheQuickBrownFox
Camel Case	:\camel	theQuickBrownFox
Kebab Case	:\kebab	the-quick-brown-fox
Upper Case	:\upper	THE QUICK BROWN FOX
Lower Case	:\lower	the quick brown fox

The variable suffix can also be used as basic regex. As an example if the variable should be enforced to be a number, this can be achieved by using :\d+.

When using the variable within a processor that supports it, you can use the string convention suffixes to convert the variable value to a specific string convention.

Asset Processors

Asset Processors are similar asset postprocessors that are executed when an asset is imported and it matches an profile and asset filter.

There are several asset processors provided and more will be added over time.

Processor	Asset Types	Descriptions
Apply Preset	Textures, Models, Audio, SpriteAtlases, Fonts, Videos	Applies a preset for the asset type
Set Asset Bundle	All	Assigns the asset bundle name and variant
Set Asset Labels	All	Assigns labels
Add To Sprite Atlas	Textures	Adds a sprite or texture to a SpriteAtlas and will create the SpriteAtlas if it does not exist
Pack Texture 2D	Textures	Packs a texture into a channel of another texture
Extract Materials	Models	Extracts materials from a model
Setup Materials	Models	Sets up materials from a model - Sets shader, properties, and assigns textures if they are found
Strip Mesh Data	Models	Strips mesh data from model, such as vertex colors, other uv channels
Reset Transform	Models	Resets position, rotation and scale on the model root object
Create Prefab	Models	Creates a prefab with the option to set layer, tag and mesh renderer(s) settings

User Data within the .meta file

Most processors will add custom user data to the meta file. This is done to signify that it has processed the asset and prevent multiple applications of the processor to the asset when it should only run once.

Custom Processors

Custom processors can be created by them via code. This is done by inheriting from the AssetProcessor class.

The AssetProcessorDescription attribute will allow you to setup a custom icon and assign what asset types are viable for your processor. The default will make the processor available for all asset types.

Here is an example processor that will set labels on assets

using System.Linq;
using Daihenka.AssetPipeline.Import;
using UnityEditor;
using UnityEngine;

[AssetProcessorDescription("FilterByLabel@2x")]
public class SetAssetLabels : AssetProcessor
{
    [SerializeField] string[] Labels;

    public override void OnPostprocess(Object asset, string assetPath)
    {
        var assetLabels = AssetDatabase.GetLabels(asset).ToHashSet();
        assetLabels.AddRange(labels);
        AssetDatabase.SetLabels(asset, assetLabels.ToArray());
        
        // Update the user data in the meta file
        ImportProfileUserData.AddOrUpdateProcessor(assetPath, this);
    }
}

How to Use

Open the Import Profiles window via the Tools > Asset Pipeline > Import Profiles menu item.

From here you can create Import Profiles via the Create New button.

Once you have created an import profile, double click on the item to open the editor for it.

Here you can specify the Base Folder and setup any Asset Filters and Processors.