Creating Assets On The Fly

Question

I want to create an asset on the fly from a file system resource. I have a bunch of text files that are used as content in my game and I want to be replace/update the files prior to building without actually having to open Unity to do it. I thought I might accomplish this by using the command line features with an Editor script that used C# file IO to load my file system resources, create new assets, and then create a new AssetBundle.

The part I haven't figured out is how to create a TextAsset from a file. This appears to be done internally? Any pointers are appreciated.

Answer 1

In the end I went with the Bash script below. This script takes a directory and creates an asset bundle with all the files in the directory. It does that by first creating a temporary Unity project in /tmp, then copying the files to Assets, then it creates a script in the Editor directory that uses BuildPipeline to create the AssetBundle. Anyway, usage is:

script.sh MyDirectoryToBundlify MyAssetBundle.unity3d

Just made it up earlier today, no guarantee there aren't bugs.

#!/bin/bash

UNITY_EXEC=/Applications/Unity/Unity.app/Contents/MacOS/Unity

if [ -z "$2" ]; then echo "You must provide a path to the bundle assets and a path to the resulting bundle."; exit 1; fi

export UNITY_ASSET_BUNDLE_PATH=${2}

CREATION_TIME=`date +%s` ASSET_BUNDLE_PROJECT_DIR=/tmp/AssetBundle-${CREATION_TIME}

echo "Creating temporary project."; ${UNITY_EXEC} -batchmode -quit -createProject ${ASSET_BUNDLE_PROJECT_DIR};

Copy the project assets from the source folder

cho "Copying resources from source folder to assets folder."; cd $1; cp -r . ${ASSET_BUNDLE_PROJECT_DIR}/Assets;

echo "Finding assets."; cd ${ASSET_BUNDLE_PROJECT_DIR}; ASSETS_TO_BUNDLE=`find Assets -type f -name "." | sed 's/^.\///g' | sed 's/^/assetPathsList.Add("/g' | sed 's/$/");/g'`

Copy the bundler script into the project

kdir ${ASSET_BUNDLE_PROJECT_DIR}/Assets/Editor/; cat > ${ASSET_BUNDLE_PROJECT_DIR}/Assets/Editor/AssetsBundler.cs assetPathsList = new List(); ${ASSETS_TO_BUNDLE};

        ArrayList assetList = new ArrayList();

        foreach(string assetPath in assetPathsList)
        {
          Debug.Log("Loading " + assetPath);
          UnityEngine.Object[] assets = AssetDatabase.LoadAllAssetsAtPath(assetPath);
          foreach(UnityEngine.Object asset in assets)
          {
             Debug.Log("Found asset: " + asset.name);
             assetList.Add(asset);
          }
        }

        UnityEngine.Object[] allAssets = (UnityEngine.Object[]) assetList.ToArray(typeof(UnityEngine.Object));    
        BuildPipeline.BuildAssetBundle(null, allAssets, "${UNITY_ASSET_BUNDLE_PATH}", BuildAssetBundleOptions.CompleteAssets);
 }

} END

echo "Building the bundle."; ${UNITY_EXEC} -batchmode -quit -projectProject ${ASSET_BUNDLE_PROJECT_DIR} -executeMethod AssetsBundler.Bundle;

echo "Deleting temporary project."; rm -rf ${ASSET_BUNDLE_PROJECT_DIR};

Answer 2

Answer by Bampf · Jan 20, 2010 at 01:44 AM

Here is one way to do it that assumes the file is in the Resources directory of your project. This example looks for a file called "puzzles.txt".

StringReader reader = null;

TextAsset puzdata = (TextAsset)Resources.Load("puzzles", typeof(TextAsset)); // puzdata.text is a string containing the whole file. To read it line-by-line: reader = new StringReader(puzdata.text); if ( reader == null ) { Debug.Log("puzzles.txt not found or not readable"); } else { // Read each line from the file while ( (string txt = reader.ReadLine()) != null ) Debug.Log("-->" + txt); }

Note that this file (and everything in Resources) is being packaged with the rest of the game when Unity builds it.

I wrote on this topic in an article on my website, Reading Text Data Into a Unity Game. It describes other options as well. There are ways to read a textfile that is not packaged into the game. That would be preferred if (for example) you wanted to let modders edit the file without Unity or your source code.

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Ben 2 · Jan 20, 2010 at 03:21 PM 0

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The article is informative but it is the less detailed final section about Asset Bundles that concerns my question. I want the text file to reside somewhere on the file system (not necessarily in a Unity project) and then be read in by my script using C# File IO. The script would then convert the text files to TextAsset objects somehow and create an asset bundle using BuildPipeline.

Bampf · Jan 21, 2010 at 12:49 AM 0

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Cool. $$anonymous$$aybe I'll link to this q&a from the article to help fill in that gap.

Answer 3

To solve my problem I wrote one script to load the files from the file system using C# System.IO and a class that extends AssetPostprocessor. By creating/copying my files from the file system to a location under the project directories the AssetPostProcessor is called. It collects the assets I'm interested in and then writes them out to a new AssetBundle using BuildPipeline.BuildAssetBundle. Here's a simplified version of each:

using UnityEngine; using UnityEditor; using System.Collections; using System.IO;

public class AssetBundleBuilder : ScriptableObject {

[MenuItem ("Custom/Create Asset")] static void CreateAsset() { 
 FileStream file = new FileStream("/Users/ben/AssetBundleSandbox/Assets/testFile.xml", FileMode.OpenOrCreate, FileAccess.Write); StreamWriter sw = new StreamWriter(file); sw.Write("Hello World"); sw.Close(); file.Close();

 AssetDatabase.Refresh(ImportAssetOptions.Default);

}

}

using UnityEngine; using UnityEditor; using System.Collections;

public class CustomPostProcessor : AssetPostprocessor { public static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths) { Object[] assetObjects = new Object[importedAssets.Length]; int assetIndex = 0;

 foreach(string importedAsset in importedAssets) { Debug.Log("Postprocessing " + importedAsset + "!"); assetObjects[assetIndex] = AssetDatabase.LoadAssetAtPath(importedAsset, typeof(TextAsset)); }

 bool buildSuccessful = BuildPipeline.BuildAssetBundle(null, assetObjects, "/tmp/TestAssetBundle.unity3d", BuildAssetBundleOptions.CompleteAssets); if(buildSuccessful) { Debug.Log("Success!"); } else { Debug.Log("Failed!");
 } }

}

So I never end up having to create the assets directly but the end result is files outside of a Unity project are imported and then stored in an AssetBundle, which is what I needed.

Answer 4

Answer by saurabh · Apr 29, 2011 at 12:31 PM

is it like i can change my prefab later on ??

can u mail me the entire pachage to test plz

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Bunny83 · May 06, 2011 at 06:11 AM 0

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Use comments if you have questions or comments to an answer! The Answer function is meant to give an answer to this question. Please read the FAQs. http://answers.unity3d.com/faq

Answer 5

a mod of unitycoder's code and create prefab from selected code:

Note: edit the code to make assets and prefabs in different folders because they have same icons in unity and it will be confusing so make 2 subfolders in savedmesh folder for each.

 using UnityEditor;
 using UnityEngine;
  
 /// <summary>
 /// Creates a prefab from a selected game object.
 /// </summary>
 class CreatePrefabFromSelected
 {
     const string menuName = "GameObject/Create Prefab From Selected";
     
     /// <summary>
     /// Adds a menu named "Create Prefab From Selected" to the GameObject menu.
     /// </summary>
     [MenuItem(menuName)]
     static void CreatePrefabMenu ()
     {
         var go = Selection.activeGameObject;
         
         Mesh m1 = go.GetComponent<MeshFilter>().mesh;//update line1
         AssetDatabase.CreateAsset(m1, "Assets/savedMesh/" + go.name +"_M" + ".asset"); // update line2
         
         
         var prefab = EditorUtility.CreateEmptyPrefab("Assets/savedMesh/" + go.name + ".prefab");
         EditorUtility.ReplacePrefab(go, prefab);
         AssetDatabase.Refresh();
     }
     
     /// <summary>
     /// Validates the menu.
     /// The item will be disabled if no game object is selected.
     /// </summary>
     /// <returns>True if the menu item is valid.</returns>
     [MenuItem(menuName, true)]
     static bool ValidateCreatePrefabMenu ()
     {
         return Selection.activeGameObject != null;
     }
 }

Creating Assets On The Fly

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Copy the project assets from the source folder

Copy the bundler script into the project

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