Evan X. Merz

Rendering audio to a file is an important feature of an audio synthesizer, but if the user can't share the file, then it's not very useful. In my second pass on my synthesizers, I'm adding the ability to share rendered audio files using email or text message.

The code for sharing audio files is tricky. You have to tell Unity to generate some Java code that launches something called an Intent. So this code basically instantiates the Java classes for the Intent and the File, then starts the activity for the intent.

Figuring out the code is tough, but you also need to change a setting in your player settings. Specifically, I couldn't get this code to work without Write Access: External (SDCard) enabled in Player Settings. Even if I am writing to internal storage only, I need to tell Unity to request external write access. I'm assuming that the extra privileges are needed for sharing the file.

Here's the code.

public static void ShareAndroid(string path)
{
    // create the Android/Java Intent objects
    AndroidJavaClass intentClass = new AndroidJavaClass("android.content.Intent");
    AndroidJavaObject intentObject = new AndroidJavaObject("android.content.Intent");

    // set properties of the intent
    intentObject.Call("setAction", intentClass.GetStatic("ACTION_SEND"));
    intentObject.Call("setType", "*/*");

    //instantiate the class Uri
    AndroidJavaClass uriClass = new AndroidJavaClass("android.net.Uri");

    // log the attach path
    Debug.Log("Attempting to attach file://" + path);

    // check if the file exists
    AndroidJavaClass fileClass = new AndroidJavaClass("java.io.File");
    AndroidJavaObject fileObject = new AndroidJavaObject("java.io.File", path);// Set Image Path Here
    //instantiate the object Uri with the parse of the url's file
    AndroidJavaObject uriObject = uriClass.CallStatic("parse", "file://" + path);
    // call the exists method on the File object
    bool fileExist = fileObject.Call("exists");
    Debug.Log("File exists: " + fileExist);

    // attach the Uri instance to the intent
    intentObject.Call("putExtra", intentClass.GetStatic("EXTRA_STREAM"), uriObject);

    // instantiate the current activity    
    AndroidJavaClass unity = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
    AndroidJavaObject currentActivity = unity.GetStatic("currentActivity");

    // start the new intent - for this to work, you must have Write Access: External (SDCard) enabled in Player Settings!
    currentActivity.Call("startActivity", intentObject);
}

Granular is a granular synthesizer for Android devices. Play it by dragging your fingers around the waveform for the source audio file. You can upload your own audio files, or just play with the sounds that are distributed with the app.

The horizontal position on the waveform controls the location from which grains will be pulled. The vertical position controls the grain size. The leftmost slider controls the amount of frequency modulation applied to the grains. The middle slider controls the time interval between grains. The rightmost slider controls randomness.

Download Granular from the Google Play Store and start making grainy soundscapes on your phone.

EDIT: I have been unable to continue maintaining this app, so it is no longer available

Asset bundles in Unity can be tricky. I've spent a lot of time at work developing a pretty slick bundling system. The system pulls the latest from our git repo, then uses manifests to pull in new procedural assets, then generates all the bundles for each level, then uploads them into versioned folders on Amazon S3.

Most big projects will need something like this.

But it's probably best to start with something simpler. The system I've built for work is probably 500 – 1000 lines of code with everything included. This weekend I wanted to find the least amount of code with which I could make a working bundles system.

This system has no extra features. It doesn't support simulation mode. It doesn't support procedural assets. It doesn't support multiple simultaneous downloads. It doesn't support viewing download progress. But it does work.

Here's how to get Unity asset bundles working in under 200 lines of code.

Download the AssetBundleManager from the Asset Store

You don't need the examples. You're really only using this for the UI features added to the Editor, but some of the included classes in that package are also a good starting point.

Assign assets to bundles

When you select an asset, you should see a drop down all the way at the very bottom of the inspector. Use that dropdown to create a new asset bundle, then add your assets to it.

Create editor script for clearing bundle cache

When you are testing bundles, you will need an extra menu item to delete your local cache. Make an Editor folder somewhere and drop this script in it.

using UnityEngine;
using UnityEditor;

public class BundleOptions
{
    /// 

    /// Delete all cached bundles. This is necessary for testing.
    /// 

    [MenuItem("Assets/AssetBundles/Clear Bundle Cache")]
    static void LogSelectedTransformName()
    {
        if( Caching.CleanCache() )
        {
            Debug.Log("All asset bundles deleted from cache!");
        }
        else
        {
            Debug.LogWarning("Unable to delete cached bundles! Are any bundles in use?");
        }
    }
}

You will want to click Assets > AssetBundles > Clear Bundle Cache between each generation of bundles to make sure that you are using the latest version in editor.

Create a BundleManager class

Your BundleManager class will download bundles and allow the program to access asset bundles. If you expand this example, then this will be the center of your work.

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class BundleManager : MonoBehaviour
{
    // the web server where your bundles are stored - you can test this locally using file://c:/path-to-bundles/etc
#if UNITY_EDITOR
    private static string baseBundleUrl = "file://c:/example/Unity/MyGame/AssetBundles";
#else
    private static string baseBundleUrl = "http://www.example.com/MyGame/AssetBundles";
#endif

    // this dictionary will store references to each downloaded asset bundle
    private static Dictionary bundles;

    /// 

    /// Get a reference to an AssetBundle instance that has already been downloaded.
    /// 
    /// This should be used when you want to load an asset from a bundle.
    /// 

    /// the name of the bundle to get
    /// a reference to an AssetBundle or null if that bundle has not yet been downloaded or cached
    public static AssetBundle GetBundle(string name)
    {
        if( bundles != null && bundles.ContainsKey(name) )
        {
            return bundles[name];
        }
        return null;
    }

    /// 

    /// Very simple method for downloading a single bundle.
    /// Extensions to this method may include a progress monitor and a callback for when the download is complete.
    /// 

    /// the name of the bundle you want to download
    /// an IEnumerator to be run as a Coroutine
    public static IEnumerator DownloadBundle(string bundleName, System.Action downloadCallback = null)
    {
        Debug.Log("Attempting to load bundle " + bundleName + "...");

        WWW www = WWW.LoadFromCacheOrDownload(getFullBundleUrl(bundleName), 1);

        yield return www;

        // if there was a download error, then log it
        if( !string.IsNullOrEmpty(www.error) )
        {
            Debug.LogError("Error while downloading bundle " + bundleName + ": " + www.error);
        }
        else // if there was no download error
        {
            // try to get the downloaded bundle
            AssetBundle newBundle = www.assetBundle;

            // if the bundle is null, then log an error
            if( newBundle == null )
            {
                Debug.LogError("Unable to save bundle " + bundleName + ": Bundle is null!");
            }
            else // if a valid bundle was downloaded
            {
                if (bundles == null)
                    bundles = new Dictionary();

                // store a reference to that bundle in the dictionary
                bundles[bundleName] = newBundle;

                Debug.Log("Successfully loaded " + bundleName + ".");
            }
        }

        // if there is a downloadCallback, then call it
        if( downloadCallback != null )
        {
            downloadCallback();
        }
    }

    /// 

    /// Return a string representation of the platform that will go into the bundle path.
    /// 

    private static string getBundlePlatform()
    {
        if (Application.platform == RuntimePlatform.Android)
        {
            return "Android";
        }
        else if( Application.platform == RuntimePlatform.WindowsEditor )
        {
            return "Windows";
        }

        // maybe this is some strange version of Android? Need this for Kindle.
        return "Android";

        // do not support other platforms
        //throw new System.Exception("This platform is not supported!");
    }

    private static string getFullBundleUrl(string bundleName)
    {
        return baseBundleUrl + "/" + getBundlePlatform() + "/" + bundleName;
    }

    // Use this to initialize the bundles dictionary
    void Start ()
    {
        if (bundles == null)
            bundles = new Dictionary();
    }

}

Modify that script by replacing baseBundleUrl with the place where your bundles are stored locally for development and remotely for production.

You will also need to hook this script into the program somehow. You can attach it to a GameObject if you like, but that isn't strictly necessary. All you really need to do is start a coroutine to run the DownloadBundle method, then call GetBundle to get the download. Then just call the LoadAsset method on the asset you want to instantiate.

Generate bundles

When you click Assets > AssetBundles > Build AssetBundles, it will generate bundles for whatever platform is selected. You will need to generate bundles for your development machine and for your target platform. Make sure to modify the getBundlePlatform method to support your platform.

And…. ?

And that's it. Asset bundles are not really that complex when you boil them down. For my music apps, I just want them to store a few extra sound files that I don't want to distribute with the executable. So a system like this works fine. I just start the download when the app starts.

Of course, for larger projects you will need many more features. Versioning bundles is very important for the development and build processes. Also you will want to show a progress bar on the screen. And you will want to load entire levels into bundles, which is a little more tricky. But hopefully this will get you started on the right track.

When I was teaching at UCSC and SJSU, I taught very large courses, often consisting of over 200 students. Courses that size create lots of infrastructural problems. Communication is a huge problem, but that's mostly taken care of by Canvas or Blackboard. The bigger problem for me was assessments.

I think that even well-written multiple choice quizzes are not great assessments. In multiple choice quizzes, students always have the answer presented to them. Even very difficult multiple choice quizzes never ask students to explain their reasoning. They never force students to come up with a concept from memory. They present students with the false premise that knowledge is fixed, and is simply a matter of choosing from what already exists.

So I always wanted to use other types of questions, and I did. Or at least I tried to. To incorporate even one short answer question meant hours of grading. I once did a single essay assignment for a large class, and probably spent over forty hours grading essays.

I needed a grading tool that could quickly save me time, while allowing me to diversify the types of assessments I could use on a week-to-week basis. For the past three months I've been building a website that automatically grades short answer, essay, and multiple choice questions. I call it QuizMana.com, and it's accepting applicants for the closed beta right now.

The hook of the website is automatic grading, but the purpose of it is to save teachers as much time as possible. So the grader gives a score for every question, but the site then points the teacher to all the "low confidence" scores. These are the scores where the grader didn't have enough information to be fully confident it gave an accurate score. The teacher can then grade the low confidence responses on a single page, and then they are done!

So the grader is part of a larger process that means that teachers only grade the work that actually needs their attention.

I think this can be a great tool, and I think it will save teachers a lot of time. If you're teaching a large class this semester, then give yourself a new tool, and try QuizMana.

Comments add information to your code. They don't impact the execution of that code. So how can they be bad? I believe that more commenting is better, and that comments are a vital tool in maintaining an agile codebase, but I've met many experienced developers who argue with me about comments.

The Pragmatic Programmer is an excellent book. It outlines best practices that have solidified over the last thirty years or so as software development has grown as a field. The authors share these practices as a series of tips that are justified by real world anecdotes. In a section on comments the authors say

"The DRY principle tells us to keep the low-level knowledge in the code, where it belongs, and reserve the comments for other, high-level explanations. Otherwise, we're duplicating knowledge, and every change means changing both the code and the comments. The comments will inevitably become out of date, and untrustworthy comments are worse than no comments at all"

They make the point that obsolete comments are worse than no comments at all. This is undoubtably true, but it has been bastardized by many programmers as an excuse for not commenting. I've heard this excuse, along with two others to justify a lack of comments in code.

1. The code is self-commenting.
2. Out of date comments are worse than no comments.
3. You shouldn't rely on comments.

In this post I want to address each of these points. I think that thorough commenting speeds up the rate of consumption of code, and that obsolete comments are a failure in maintenance, rather than in comments in general.

1. The code is self-commenting

This is the excuse I hear most often from developers who don't comment their code. The thinking is that clear variable and method names replace the need for comments. There are situations where this is true. For very short methods with a single purpose, I see that no additional comments may be necessary.

But most methods are not very short, and most methods achieve several things that relate to one overall purpose. So in the first place, very few methods fit the bill.

This is not a valid complaint because good comments only make the code easier to read. While the code may be legible on its own, a comment that explains the purpose of a method, or the reason for a string operation, can only make it easier to read. The author of Clean Code agrees due to the amount of time we spend reading code.

"the ratio of time spent reading vs. writing is well over 10:1. We are constantly reading old code as part of the effort to write new code. Because this ratio is so high, we want the reading of code to be easy, even if it makes the writing harder."

Because we spend more time reading code than writing it, a responsible programmer knows that the extra comment in a method which takes very little time to write may well save another programmer many hours of learning.

2. Out of date comments are worse than no comments

To refute this argument, lets take cars as an analogy. If you buy a car, then drive it for twenty thousand miles without an oil change, it will break down. If you did that, the fault wouldn't be in cars in general. Rather, the fault is in the lack of maintenance.

Similary, obsolete comments are not a failure of comments in general, but a failure of the programmer who updated the code without updating the comments. That other programmers have bad practices does not justify continuing that bad practice.

Obsolete comments are a broken window. If you see them, it is your job to fix them.

So while obsolete comments ARE worse than no comments, that argument is an argument against bad coding practices, not comments in general.

3. You shouldn't rely on comments

The argument that a programmer shouldn't rely on comments is a subtle dig at another programmer's skill. They're saying "a good programmer can understand this code with no comments."

There is a grain of a valid point there. If you consider yourself a seasoned programmer, then you should be accustomed to wading through large volumes of old code and parsing out the real meaning and functionality.

But even for veteran programmers, comments make it easier to read and understand the code. It's much easier to interpret a one line summary of a block of code than to parse that block line by line. It's much easier to store that one line in your head than it is to store the whole block in your head.

The real reason why this is the worst of excuses is that not all programmers working on your code are senior programmers. Some are green graduates straight out of college. Yes, a more experienced programmer could understand the code without comments, but it will cost that graduate hours to figure out what they could have gotten in minutes with good comments.

My Commenting Principle

Comment your code so that a green programmer can understand it.

Or…

Comment your code so that your boss can understand it.

What does it take to make your code readable by a green graduate? Imagine them going through it line by line. If there are no comments, then they need to understand every function call, and every library routine. They need to understand a bit about your architecture and date model.

Now imagine that every single line is commented.

In that scenario, a green programmer can read your file by reading one comment after the next. If they need more information, they can still drill into the code and get the details, but they can understand the overview just through comments.

The closer you can get to that, the better.

Don't listen to the arguments against thorough commenting habits. Just point the detractors here.