Effective OpenAL with LWJGL 3

Effective OpenAL with LWJGL 3

Jesus Bloody Christ it’s been a while.

So, a lot of you are likely interested in developing on Java with LWJGL3 instead of LWJGL 2.9.*; as you should be. LWJGL3 has support for a lot of modern industry trends with older versions did not; such as multi-monitor support without back flipping through flaming hoops, or basically anything involving GLFW. It’s still in beta, I know, but it’s a solid piece of work and the team on it is dedicated enough to make it a reliable and standing dependency for modern projects.

Except for every now and then, when it happens to be missing some minor things. Or, more importantly, when there’s a dearth of documentation or tutorials on a new trick you’re pulling.

I can contribute, at least in part, to both of those.

OpenAL is the audio world’s equivalent to OpenGL; it’s a sophisticated and sleek interface to sound hardware. Many common effects and utilities, such as 3D sound, are built into it directly; and it interfaces sublimely with code already designed for OpenGL. Additionally, it’s also a very tight interface that does not take long at all to learn.

In the past, I would suggest using JavaSound for Java game audio, which is also a tight API, but it lacks these features. Most major audio filters have to be built into it rather directly and often by your own hand; and there’s no official guarantee of hardware optimization. However, what LWJGL3’s OpenAL interface now lacks can easily be supported by readily-present JavaSound features; such as the audio system’s file loader.

This entry is on, step by step, how one would do such a thing.

Let’s start with a basic framework. I’ve tried to keep a balance between minimal dependencies and staying on-topic, so I’ll suggest that you have both LWJGL3 (most recent version, preferably), and Apache Commons IO, as dependency libraries.

class Lesson {
    public Lesson() throws Exception {
        //Start by acquiring the default device
        long device = ALC10.alcOpenDevice((ByteBuffer)null);

        //Create a handle for the device capabilities, as well.
        ALCCapabilities deviceCaps = ALC.createCapabilities(device);
        // Create context (often already present, but here, necessary)
        IntBuffer contextAttribList = BufferUtils.createIntBuffer(16);

        // Note the manner in which parameters are provided to OpenAL...


        // Don't worry about this for now; deals with effects count

        //create the context with the provided attributes
        long newContext = ALC10.alcCreateContext(device, contextAttribList);
        if(!ALC10.alcMakeContextCurrent(newContext)) {
            throw new Exception("Failed to make context current");
        //define listener
        AL10.alListener3f(AL10.AL_VELOCITY, 0f, 0f, 0f);
        AL10.alListener3f(AL10.AL_ORIENTATION, 0f, 0f, -1f);
        IntBuffer buffer = BufferUtils.createIntBuffer(1);
        //We'll get to this next!
        long time = createBufferData(buffer.get(0));
        //Define a source
        int source = AL10.alGenSources();
        AL10.alSourcei(source, AL10.AL_BUFFER, buffer.get(0));
        AL10.alSource3f(source, AL10.AL_POSITION, 0f, 0f, 0f);
        AL10.alSource3f(source, AL10.AL_VELOCITY, 0f, 0f, 0f);
        //fun stuff
        AL10.alSourcef(source, AL10.AL_PITCH, 1);
        AL10.alSourcef(source, AL10.AL_GAIN, 1f);
        AL10.alSourcei(source, AL10.AL_LOOPING, AL10.AL_FALSE);
        //Trigger the source to play its sound
        try {
            Thread.sleep(time); //Wait for the sound to finish
        } catch(InterruptedException ex) {}
        AL10.alSourceStop(source); //Demand that the sound stop
        //and finally, clean up



The beginning is not unlike the creation of an OpenGL interface; you need to define an OpenAL context and make it current for the thread. Passing a null byte buffer to alcOpenDevice will provide you with the default device, which is usually what you’re after. (It is actually possible to interface with, say, multiple sets of speakers selectively, or the headphones instead of the speaker system, if you would like; but that’s another topic.)

Much like graphics devices, every audio device has its own set of capabilities. We’ll want a handle on those, as well. It’s safe to say that if a speaker can do it, OpenAL is capable of it; but not all speakers (or microphones) are created the same.

After this, OpenAL will want to know something of what we’re expecting it to manage. Note that it’s all passed over as a solid int buffer. We’re providing it with a notion of what features it will need to enact, or at least emulate; with a sequence of identifiers followed by parameters, terminated with a null. I haven’t begun to touch all that is possible here, but this attribute list should be enough for most uses.

After that, create the context, make it current, check to see that it didn’t blow up in your face, and register the capabilities. (Feel free to play with this once you’ve got the initial example going.)

So, before I get to the part where JavaSound comes in, let’s start with the nature of how OpenAL views sound. Sound, in its view, has three components: a listener, a source, and an actual buffer.

The listener would be either you or your program user; however, the program would want to know a little about your properties. Are you located something to the left or right? Are you moving (or virtually moving)? I usually set this first as it is likely to be constant across all sounds (kind of like a graphics context).

Next, we have a method of my own creation that builds and registers the audio file. Forgive me for the delay, but that’s where JavaSound’s features (in the core JKD) come in, and I’m deferring it to later in the discussion. You will note that the audio buffers have to be registered with OpenAL; as it needs to prepare for the data. There’s a solid chance that you will have sound-processor-local memory, much like graphics memory, and it will have to be managed accordingly by that processor before you can chuck any data at it.

Let’s look at that audio buffer creator.

     private long createBufferData(int p) throws UnsupportedAudioFileException, IOException {
        //shortcut finals:
        final int MONO = 1, STEREO = 2;
        AudioInputStream stream = null;
        stream = AudioSystem.getAudioInputStream(Lesson3.class.getResource("I Can Change — LCD Soundsystem.wav"));
        AudioFormat format = stream.getFormat();
        if(format.isBigEndian()) throw new UnsupportedAudioFileException("Can't handle Big Endian formats yet");
        //load stream into byte buffer
        int openALFormat = -1;
        switch(format.getChannels()) {
            case MONO:
                switch(format.getSampleSizeInBits()) {
                    case 8:
                        openALFormat = AL10.AL_FORMAT_MONO8;
                    case 16:
                        openALFormat = AL10.AL_FORMAT_MONO16;
            case STEREO:
                switch(format.getSampleSizeInBits()) {
                    case 8:
                        openALFormat = AL10.AL_FORMAT_STEREO8;
                    case 16:
                        openALFormat = AL10.AL_FORMAT_STEREO16;
        //load data into a byte buffer
        //I've elected to use IOUtils from Apache Commons here, but the core
        //notion is to load the entire stream into the byte array--you can
        //do this however you would like.
        byte[] b = IOUtils.toByteArray(stream);
        ByteBuffer data = BufferUtils.createByteBuffer(b.length).put(b);
        //load audio data into appropriate system space....
        AL10.alBufferData(p, openALFormat, data, (int)format.getSampleRate());
        //and return the rough notion of length for the audio stream!
        return (long)(1000f * stream.getFrameLength() / format.getFrameRate());

We’re hijacking a lot of the older JavaSound API utilities for this. OpenAL, much like OpenGL, isn’t really “open”, nor is it technically a “library”. So, having something around for handling audio data is helpful, and why bother writing our own when it’s already built into the JDK?

For JavaSound, you work with either Clips, or (more frequently) AudioInputStreams. You can read most audio file formats directly via AudioSystem.getAudioInputStream(…); in this case, I’ve elected to use a WAV format of LCD Soundsystem’s “I Can Change”, because James Murphy is a god damned genius. However, you can use anything you would like; to get it to work with this just drop it in the same source directory.

Next up, grab the format of the sound with AudioStream.getFormat(). This will provide you with a lot of valuable information about the stream. If it’s a big endian stream (which most wave files are not), you might need to convert it to little endian or make proper alterations to OpenAL. I’ve glossed over this, as endian-ness is not really a part of the tutorial and there are plenty of good byte-management tutorials out there.

I’ve elected to use format to check for the mono/stereo status (more are actually possible), and whether the sound is 8-bit or more frequently 16-bit. (Technically 32- or even 64- bit sound is possible; but there is actually a resolution to the cochlea of the ear, and you’re not going to bump into that outside of labs with very funny looking equipment. Even Blu-ray doesn’t go above 24-bit. Seriously, there’s generally just no point in bothering.)

Afterward, we load the stream into a byte array (I’m using IOUtils for this for brevity, but you can do it however you like), and the byte array into a ByteBuffer. Flip the buffer, and punch it over to OpenAL, which will take care of the rest of the work with it. Afterwards, we will eventually need the length of the audio stream, so calculate it as shown and send it back to the calling method.

After the buffer’s been created and the length of it is known, we’ve got to create a source for it! This is where most of the cooler built-in effects show up. alGenSources() creates a framework for the source; alSourcei(source, AL10.AL_BUFFER, buffer.get(0)) ties it to the sound buffer. You’ll also see that I set up AL_GAIN and AL_PITCH, which are fun to play with.

You’re almost done!

To actually play the buffer, you use the source. alSourcePlay(source) starts it. After that, I have the Thread sleep for the calculated length of the sound, just so we have time to hear it. At the end, I call alSourceStop(source) to demand an end to the source.

Lastly, I delete all sources. You might also want to delete devices, if you’ve done anything silly with them; this is very low-level access. You now have everything you need to load audio into your games and programs, and if you happen to bump into an SPI for a preferred format, it will now also be enough to get you going on OpenAL as well.

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Posted by on July 4, 2016 in Java, Programming


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A Studio, A Temple

I have a beautiful place carved out of the emptiness that was before. Two desks, one metal, the other dark cherry, formed into an “L”, my desktop on one and my Raspberry Pis, electronics, and embedded systems on the other. A space for my coffee, two surge protectors, an X-Box controller for the times when a mouse doesn’t do the job. A top-notch soldering pen, poised on the glass desk between my two monitors, unplugged and with plenty of space for safety of course.

This place used to be a living room, which we did little living in. I’ve adopted it, and adapted it, into a workspace. The thing about a studio is that it is, by definition, a temple to one’s mind. Nothing goes here that I wouldn’t have bouncing around in my head, whilst I’m trying to actually get something done. This place is my mind space.

I have a whiteboard on the wall now; four feet by three feet, with a complete collection of four-color markers (two black, one each in red, green, and blue) and an eraser, with a cleaning spray. I do use it. I’ve been mapping my thoughts to it for some time. It’s good when a paper pad (which every engineer should, still, always have) just isn’t enough. It doesn’t have the advantage of graph paper, but some occasions require something more than a note. Right now, I’m weighing the advantages and disadvantages between using LWJGL or JavaFX for a programming project. I would not have found it to be as easy without the marker board.

The floor bothers me. It’s an awful blue carpet, one which may never have been that attractive and hasn’t gotten any better with age. I’m hoping to replace it with some stone tile, something in a nice tan color. Not just linoleum, nothing too cheap. That would be reckless and self-sabotaging; I can wait to afford it. A nice wheat color would blend well with the furniture. The walls are a subtle greenish white, hard to tell in the lamplight late in the evening. I might paint them, it wouldn’t take long. Something bright, nothing that would contrast with the flags and the artwork hanging on them, or the statues and idols poised throughout the shelves.

When I enter this space, I become someone new; someone I need to be. I have OpenGL/CL/AL projects going on the desktop, bioelectrics going on the steel desk, and little room for doubt or distraction. My office used to be a plastic desk in the kitchen, where I would pound out every ounce of inspiration my mind had until I ran out of strength. I’m stronger in here. This place is, indeed, a sacred one to me.

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Posted by on January 26, 2016 in Innovation, State of the Moment


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Never Stop Running

Never Stop Running

You know that burning feeling you get, in the center of your chest, your very core, when you just need to get something magnificent done? Not just a frequent thing like doing laundry, or cleaning the house, but something life vindicating? Because I’ve got that lately. I’ve spent the past month taking care of all of the heat that the part-time is getting, purely for the sake of this; January should be just boring enough to finish everything off.

I say I’m a systems engineer, but generally only when I want to change subjects. The long answer is that I build machines that build universes. I have a degree that redefined what it means to be “hard-earned”; in the fields of Physics and Neuroscience. I’ve been programming since I was a tyke. I’ve been writing since I was ten years old. All of this ultimately accumulates toward the same end goal. The whole point of building simulators is to answer “what if”. Stories, games, the entertainment of the future; it’s all in systems and simulation. Everything is and always has been about that.

Back in the 1960s and 70s, before the personal computer was standing up and walking on two feet, aerospace companies like Boeing used to build tiny scale models of their aircraft before the actual prototype was ever constructed. The idea was, given that a specific part goes out and needs to be replaced on such-and-such an aeroplane, what are we going to have to pull way to get to it? What would be the cost model? If half of the aeroplane had to be pulled apart to get to a specific gearbox, then the lifetime of that gearbox might be the lifetime of the aeroplane. The design might be too expensive to fix.

Were these micro-models expensive? Absolutely. However, they were much cheaper than figuring this out only after the aircraft was built. They were worth every penny, and every replacement model was worth every penny in turn. I look at this chop-shop job, and I remind myself that. It’s my funding and my micro-model.

Yesterday, I finished off the better part of a detailed three dimensional collision detection system, with an outline to covering four dimensions if the need ever arises. It’s as modular and expandable as it can get. It was harder than it sounded, it was twice as much fun, and it’s completely self-validating. When I’m done with this, all I’ll need to worry about is penning, sculpting, composing, and storyboarding.

That, my friends, is the best Christmas present ever. Happy Solstice!

[Note: image is a rambled selfie with tonight’s desert, an orange chocolate mousse with raspberries and freshly whipped cream]

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Posted by on December 26, 2015 in State of the Moment, Uncategorized


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The Marvel DubSmash War Of SDCC 2015 – When Agents Collide, Everyone Wins!

The Marvel DubSmash War Of SDCC 2015 – When Agents Collide, Everyone Wins!

The Insightful Panda

This past Season on Agents Of SHIELD and Agent Carter, we saw a lot of ‘almost’ Civil Wars: Coulson’s S.H.I.E.L.D. vs Gonzales’ S.H.I.E.L.D., Agent Carter vs the SSR. Thankfully those two resolved peacefully and it seemed like we’d have to wait for Captain America: Civil War to see the next battle. Well, we were wrong because a new war brewed this past weekend at San Diego Comic Con when all these Agents met up at the fists lip syncing flew! DubSmash War!

At approximately 8:08 PM on Jun 10th – sometime after the Marvel TV Panel – the challenge was issued by Clark Gregg (Agent Phil Coulson) and Chloe Bennet (Agent Skye/Daisy).

What was this strange new battlefield? Hayley and Atwell (Agent Carter) and James Darcy (Edwin Jarvis) were up for the challenge, but first wanted to practice a little…

… and then, officially accepted the challenge 2 hours later that…

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Posted by on July 13, 2015 in Uncategorized


Google Deep Dream ruins food forever.

Giger rest in peace. He would have had so much fun with Deep Dream.

Ken Vermette

Google Deep Dream is an interesting piece of AI software which looks for patterns in pictures, much like humans may look for patterns in clouds. Deep Dream has been trained to find a few things, like eyes, animals, arches, pagodas, and the most fascinating part is that Deep Dream can also spit out what it “saw”. Then Google opened Deep Dream to the public and people started loading tonnes of images into the system, and when you combine food with Deep Dream it turns into the stuff of nightmares.

RUN NOW OR FOREVER RUIN FOOD FOREVER! Here’s pictures of food turned to ghoulish nightmare-fuel courtesy of Deep Dream;

Via Steve Kaiser Via Steve Kaiser

Nope. NOPE. Great start. Never eating takeout again. At least nothing bad can happen to the humble doughnut.

Duncan Nicoll, thank you. Via Ibitimes Duncan Nicoll, thank you. Via Ibitimes

GREAT. FANTASTIC. I didn’t like doughnuts anyway. ARE THOSE LEGS?

Ibitimes also had this. Spaghetti & nightmares.Ibitimes also had this. Spaghetti…

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Posted by on July 11, 2015 in Uncategorized


Apache Commons DecompositionSolvers

Apache Commons DecompositionSolvers

Jesus it’s been too long since I got back to this!

Anyway, right, the


Intro / Why-I-Need-To-Worry-About-This

Linear algebra exists for a reason; namely, us. Suppose we’re attempting to find the coordinate values, which under a certain transform, become a specific value. Let’s keep it simple and call it:

 x + 2y + 3z = 1
2x + 4y + 3z = 2
4x           = 3

As I’m sure you can remember from grade school, you have the same number of equations as unknowns, so it is almost certainly solvable. We just subtract two of the first equation from the second, four of the first equation form the third, four of the second from the third, one of the second from the first, and a quarter of the third from the first. Then we maybe divide the third by eight and the second by three, and presto,

x = 3/4
y = 1/8
z = 0

Unfortunately, as programmers, we both know that this is much easier done in practice than in theory; and when you’re automating  a task, a working theory is the only thing that really counts.

So, those of you who have already taken linear algebra (quite possibly all of you) may be familiar with a much easier way of representing this problem:

┌1 2 3┐┌x┐   ┌1┐
│2 4 3││y│ = │2│
└4 0 0┘└z┘   └3┘

A decomposition basically solves this, through a sequence of steps on both sides that reduces the original matrix to an identity matrix, while having the right-hand matrix undergo the same operations. This is commonly written as an augmented matrix, like so:

┌1 2 3│1┐
│2 4 3│2│
└4 0 0│3┘

Matrix reduction is a heck of a lot more straightforward than the nonsense I spouted a few paragraphs back, though going into its details is a bit off topic here. Our final matrix, after the reduction, looks like this:

┌1 0 0│3/4┐
│0 1 0│1/8│
└0 0 1│ 0 ┘

How Do We Do This in Java?

Not just Java, actually; this is specifically about the Apache Commons Math3 decomposition solver interface.

One of the tricks with reduction is that there are a lot of different, equally effective, ways to go about it; and like any other algorithm, the efficiency depends, in large part, on the initial state of your matrix. My personal favorite is the LU Decomposition. (Or, if you prefer a link that isn’t a video, look here.)

First I recommend making a Maven project out of your Java project, presuming that it isn’t already fitting that form factor. Afterwards, open up pom.xml, and add this:


right after the close of the build tag. Your project is now pulling classes from across the internet, on Apache Commons Math3. Later on, you may want the version number to be a bit higher; for now I’m using version 3.5.

So, you’ll note that you have access to a host of new classes, all in some subpackage of org.apache.commons.math3. Import org.apache.commons.math3.linear.* into your class file.

We can solve the above problem by creating a RealMatrix of the initial matrix, potentially like so:

RealMatrix matrix = new Array2DRowRealMatrix(new double[][]{
    {1.0, 2.0, 3.0},
    {2.0, 4.0, 3.0},
    {4.0, 0.0, 0.0}

But don’t get me wrong, there are literally dozens of ways to create a RealMatrix.

Next, create a RealVector, describing the other side of the equation, perhaps like so:

RealVector vector = new ArrayRealVector(new double[]{

We now have a matrix and vector representation of the two sides of our equation.

Working with RealMatrix and RealVector

If you’re an experienced programmer, you probably expect some kind of Command Pattern to show up next. It’s certainly what I would do, if I needed to duplicated the exact operations in the exact order on more than one piece of base data. Fortunately, something like it has already been implemented by Apache.

If you look up the Apache Commons Math3 javadocs, you’ll notice that while RealMatrix has a lot of handy operations, they generally just involve polling for data, not actually operating on it. Commons has made the wise move to encapsulate operations in their own classes, rather than just their own methods. There are many dozen other classes, such as MatrixUtils (remember that one!), which both generate and operate on RealMatrix and RealVector classes.

In this instance, turn to DecompositionSolver. It’s meant for tasks just like our own, and there are many subclasses. As I said, my preference is LUDecomposition, but that is only capable of handling square matrices. Since our matrix is square, that’s fine; in other cases when your matrix doesn’t fit the profile, look through EigenDecomposition, SingularValueDecomposition, or some other utility.

For LUDecomposition, we’ll want to do something like this:

DecompositionSolver solver = new LUDecomposition(matrix).getSolver();

The work has been done, as one initialization, LUDecomposition doesn’t just store the matrix as a property; it determines from it the exact sequence of operations necessary to turn it into an identity matrix.

Once you have your solver, you can get your final right-hand vector via:


which will provide you with:

└ 0 ┘

Final Source Code

Here’s a working example of how such a program might work.

 package oberlin.math3;

import java.util.*;

import org.apache.commons.math3.linear.*;

public class MatrixReducer {
    public static void main(String...args) {
        new MatrixReducer();
    public MatrixReducer() {
        try(BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
                Scanner scanner = new Scanner( {
            writer.write("\nEnter first row of three numbers: ");
            RealVector vector1 = new ArrayRealVector(new double[]{scanner.nextDouble(), scanner.nextDouble(), scanner.nextDouble()});
            writer.write("\nEnter second row of three numbers: ");
            RealVector vector2 = new ArrayRealVector(new double[]{scanner.nextDouble(), scanner.nextDouble(), scanner.nextDouble()});

            writer.write("\nEnter third row of three numbers: ");
            RealVector vector3 = new ArrayRealVector(new double[]{scanner.nextDouble(), scanner.nextDouble(), scanner.nextDouble()});
            //create matrix
            RealMatrix matrix = MatrixUtils.createRealIdentityMatrix(3);
            matrix.setRowVector(0, vector1);
            matrix.setRowVector(1, vector2);
            matrix.setRowVector(2, vector3);
            //get other side
            writer.write("\nEnter vector on right side (3 entries):");
            RealVector vector = new ArrayRealVector(new double[]{scanner.nextDouble(), scanner.nextDouble(), scanner.nextDouble()});
            DecompositionSolver solver = new LUDecomposition(matrix).getSolver();
            matrix = solver.solve(matrix);
            vector = solver.solve(vector);
            writer.write("Solution: \n");
            writer.write("┌" + matrix.getEntry(0, 0) + " " + matrix.getEntry(0, 1) + " "
                    + matrix.getEntry(0, 2) + "┐┌x┐   ┌" + Double.toString(vector.getEntry(0)) + "┐\n");
            writer.write("│" + matrix.getEntry(1, 0) + " " + matrix.getEntry(1, 1) + " "
                    + matrix.getEntry(1, 2) + "││y│ = │" + Double.toString(vector.getEntry(1)) + "│\n");
            writer.write("└" + matrix.getEntry(2, 0) + " " + matrix.getEntry(2, 1) + " "
                    + matrix.getEntry(2, 2) + "┘└z┘   └" + Double.toString(vector.getEntry(2)) + "┘\n");
        } catch (IOException e) {
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Posted by on June 30, 2015 in Java, Programming


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Famous Works of Art Improved by Cats


If there’s any one thing that could improve a Botticelli painting, what would it be? Well, a big furry cat, of course! Okay, so obviously we’re not serious, but that doesn’t make this series of cat-augemnted artworks, which we first heard about over at It’s Nice That, any less hilarious. Over at Great Artists’ Mews, Zarathustra the cat wants to get the record straight — Mona Lisa was only smiling like that because she had a fat tabby squirming in her arms. The site comes with this very cat-like disclaimer: “We are real. All the artworks at this site are real. Nobody’s opinion about Us, Our art or this site will ever disturb Our suprematism.” Fair enough. Click through to see some of our favorites, and if you’re not all kittied out, head over to Great Artists’ Mews for even more cat-infiltrated art.

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Posted by on April 5, 2015 in Uncategorized