Welcome to the wonderful world of mobile game development. Whether you are still looking for the right development kit or have already chosen one, this article will be very important. In this article by Tom Finnegan, the author of Learning Unity Android Game Development, we explore the various features that come with choosing Unity as your development environment and Android as the target platform. Through comparison with major competitors, it is discovered why Unity and Android stand at the top of the pile. Following this, we will examine how Unity and Android work together. Finally, the development environment will be set up and we will create a simple Hello World application to test whether everything is set up correctly.

(For more resources related to this topic, see here.)

In this article, we will cover the following topics:

• Major Unity features
• Major Android features
• Unity licensing options
• Installing the JDK
• Installing the Android software development kit (SDK)
• Installing Unity 3D
• Installing Unity Remote

Understanding what makes Unity great

Perhaps the greatest feature of Unity is how open-ended it is. Nearly all game engines currently on the market are limited in what one can build with them. It makes perfect sense but it can limit the capabilities of a team. The average game engine has been highly optimized for creating a specific game type. This is great if all you plan on making is the same game again and again. It can be quite frustrating when one is struck with inspiration for the next great hit, only to find that the game engine can't handle it and everyone has to retrain in a new engine or double the development time to make the game engine capable. Unity does not suffer from this problem. The developers of Unity have worked very hard to optimize every aspect of the engine, without limiting what types of games can be made using it. Everything ranging from simple 2D platformers to massive online role-playing games are possible in Unity. A development team that just finished an ultrarealistic first-person shooter can turn right around and make 2D fighting games without having to learn an entirely new system.

Being so open-ended does, however, bring a drawback. There are no default tools that are optimized for building the perfect game. To combat this, Unity grants the ability to create any tool one can imagine, using the same scripting that creates the game. On top of that, there is a strong community of users that have supplied a wide selection of tools and pieces, both free and paid, that can be quickly plugged in and used. This results in a large selection of available content that is ready to jump-start you on your way to the next great game.

When many prospective users look at Unity, they think that, because it is so cheap, it is not as good as an expensive AAA game engine. This is simply not true. Throwing more money at the game engine is not going to make a game any better. Unity supports all of the fancy shaders, normal maps, and particle effects that you could want. The best part is that nearly all of the fancy features that you could want are included in the free version of Unity, and 90 percent of the time beyond that, you do not even need to use the Pro-only features.

One of the greatest concerns when selecting a game engine, especially for the mobile market, is how much girth it will add to the final build size. Most game engines are quite hefty. With Unity's code stripping, the final build size of the project becomes quite small. Code stripping is the process by which Unity removes every extra little bit of code from the compiled libraries. A blank project compiled for Android that utilizes full code stripping ends up being around 7 megabytes.

Perhaps one of the coolest features of Unity is its multi-platform compatibility. With a single project, one can build for several different platforms. This includes the ability to simultaneously target mobiles, PCs, and consoles. This allows you to focus on real issues, such as handling inputs, resolution, and performance.

In the past, if a company desired to deploy their product on more than one platform, they had to nearly double the development costs in order to essentially reprogram the game. Every platform did, and still does, run by its own logic and language. Thanks to Unity, game development has never been simpler. We can develop games using simple and fast scripting, letting Unity handle the complex translation to
each platform.

Unity – the best among the rest

There are of course several other options for game engines. Two major ones that come to mind are cocos2d and Unreal Engine. While both are excellent choices,
you will find them to be a little lacking in certain respects.

The engine of Angry Birds, cocos2d, could be a great choice for your next mobile hit. However, as the name suggests, it is pretty much limited to 2D games. A game can look great in it, but if you ever want that third dimension, it can be tricky to add it to cocos2d; you may need to select a new game engine. A second major problem with cocos2d is how bare bones it is. Any tool for building or importing assets needs to be created from scratch, or it needs to be found. Unless you have the time and experience, this can seriously slow down development.

Then there is the staple of major game development, Unreal Engine. This game engine has been used successfully by developers for many years, bringing great games to the world Unreal Tournament and Gears of War not the least among them. These are both, however, console and computer games, which is the fundamental problem with the engine. Unreal is a very large and powerful engine. Only so much optimization can be done on it for mobile platforms. It has always had the same problem; it adds a lot of girth to a project and its final build. The other major issue with Unreal is its rigidity in being a first-person shooter engine. While it is technically possible to create other types of games in it, such tasks are long and complex. A strong working knowledge of the underlying system is a must before achieving such a feat.

All in all, Unity definitely stands strong amidst game engines. But these are still great reasons for choosing Unity for game development. Unity projects can look just as great as AAA titles. The overhead and girth in the final build are small and this is very important when working on mobile platforms. The system's potential is open enough to allow you to create any type of game that you might want, where other engines tend to be limited to a single type of game. In addition, should your needs change at any point in the project's life cycle, it is very easy to add, remove, or change your choice of target platforms.

Understanding what makes Android great

With over 30 million devices in the hands of users, why would you not choose the Android platform for your next mobile hit? Apple may have been the first one out of the gate with their iPhone sensation, but Android is definitely a step ahead when it comes to smartphone technology. One of its best features is its blatant ability to be opened up so that you can take a look at how the phone works, both physically and technically. One can swap out the battery and upgrade the micro SD card on nearly all Android devices, should the need arise. Plugging the phone into a computer does not have to be a huge ordeal; it can simply function as a removable storage media.

From the point of view of the cost of development as well, the Android market is superior. Other mobile app stores require an annual registration fee of about
100 dollars. Some also have a limit on the number of devices that can be registered for development at one time. The Google Play market has a one-time registration
fee of 25 dollars, and there is no concern about how many Android devices or
what type of Android devices you are using for development.

One of the drawbacks of some of the other mobile development kits is that you have to pay an annual registration fee before you have access to the SDK. With some, registration and payment are required before you can view their documentation. Android is much more open and accessible. Anybody can download the Android SDK for free. The documentation and forums are completely viewable without having to pay any fee. This means development for Android can start earlier,
with device testing being a part of it from the very beginning.

Understanding how Unity and Android work together

As Unity handles projects and assets in a generic way, there is no need to create multiple projects for multiple target platforms. This means that you could easily start development with the free version of Unity and target personal computers. Then, at a later date, you can switch targets to the Android platform with the click of a button. Perhaps, shortly after your game is launched, it takes the market by storm and there is a great call to bring it to other mobile platforms. With just another click of the button, you can easily target iOS without changing anything in your project.

Most systems require a long and complex set of steps to get your project running on a device. However, once your device is set up and recognized by the Android SDK, a single button click will allow Unity to build your application, push it to a device, and start running it. There is nothing that has caused more headaches for some developers than trying to get an application on a device. Unity makes this simple.

With the addition of a free Android application, Unity Remote, it is simple and easy to test mobile inputs without going through the whole build process. While developing, there is nothing more annoying than waiting for 5 minutes for a build every time you need to test a minor tweak, especially in the controls and interface. After the first dozen little tweaks, the build time starts to add up. Unity Remote makes it simple and easy to test everything without ever having to hit the Build button.

These are the big three reasons why Unity works well with Android:

• Generic projects
• A one-click build process
• Unity Remote

We could, of course, come up with several more great ways in which Unity and Android can work together. However, these three are the major time and money savers. You could have the greatest game in the world, but if it takes 10 times longer to build and test, what is the point?

Differences between the Pro and Basic versions of Unity

Unity comes with two licensing options, Pro and Basic, which can be found at https://store.unity3d.com. If you are not quite ready to spend the 3,000 dollars that is required to purchase a full Unity Pro license with the Android add-on, there are other options. Unity Basic is free and comes with a 30-day free trial of Unity Pro. This trial is full and complete, as if you have purchased Unity Pro, the only downside being a watermark in the bottom-right corner of your game stating Demo Use Only. It is also possible to upgrade your license at a later date. Where Unity Basic comes with mobile options for free, Unity Pro requires the purchase of Pro add-ons for each of the mobile platforms.

An overview of license comparison

License comparisons can be found at http://unity3d.com/unity/licenses. This section will cover the specific differences between Unity Android Pro and Unity Android Basic. We will explore what the features are and how useful each one is in the following points:

NavMeshes, pathfinding, and crowd simulation

This feature is Unity's built-in pathfinding system. It allows characters to find their way from a point to another around your game. Just bake your navigation data in the editor and let Unity take over at runtime. Until recently, this was a Unity Pro only feature. Now the only part of it that is limited in Unity Basic is the use of off-mesh links. The only time you are going to need them is when you want your AI characters to be able to jump across and otherwise navigate around gaps.

LOD support

LOD (short for level of detail) lets you control how complex a mesh is, based on its distance from the camera. When the camera is close to an object, you can render a complex mesh with a bunch of detail in it. When the camera is far from that object, you can render a simple mesh because all that detail is not going to be seen anyway. Unity Pro provides a built-in system to manage this. However, this is another system that could be created in Unity Basic. Whether or not you are using the Pro version, this is an important feature for game efficiency. By rendering less complex meshes at a distance, everything can be rendered faster, leaving more room for awesome gameplay.

The audio filter

Audio filters allow you to add effects to audio clips at runtime. Perhaps you created gravel footstep sounds for your character. Your character is running and we can hear the footsteps just fine, when suddenly they enter a tunnel and a solar flare hits, causing a time warp and slowing everything down. Audio filters would allow us to warp the gravel footstep sounds to sound as if they were coming from within a tunnel and were slowed by a time warp. Of course, you could also just have the audio guy create a new set of tunnel gravel footsteps in the time warp sounds, although this might double the amount of audio in your game and limit how dynamic we can be with it at runtime. We either are or are not playing the time warp footsteps. Audio filters would allow us to control how much time warp is affecting our sounds.

Video playback and streaming

When dealing with complex or high-definition cut scenes, being able to play videos becomes very important. Including them in a build, especially with a mobile target, can require a lot of space. This is where the streaming part of this feature comes in. This feature not only lets us play videos but also lets us stream a video from the Internet. There is, however, a drawback to this feature. On mobile platforms, the video has to go through the device's built-in video-playing system. This means that the video can only be played in fullscreen and cannot be used as a texture for effects such as moving pictures on a TV model. Theoretically, you could break your video into individual pictures for each frame and flip through them at runtime, but this is not recommended for build size and video quality reasons.

Fully-fledged streaming with asset bundles

Asset bundles are a great feature provided by Unity Pro. They allow you to create extra content and stream it to users without ever requiring an update to the game. You could add new characters, levels, or just about any other content you can think of. Their only drawback is that you cannot add more code. The functionality cannot change, but the content can. This is one of the best features of Unity Pro.

The 100,000 dollar turnover

This one isn't so much a feature as it is a guideline. According to Unity's End User License Agreement, the basic version of Unity cannot be licensed by any group or individual who made $100,000 in the previous fiscal year. This basically means that if you make a bunch of money, you have to buy Unity Pro. Of course, if you are making that much money, you can probably afford it without an issue. This is the view of Unity at least and the reason why there is a 100,000 dollar turnover.

Mecanim – IK Rigs

Unity's new animation system, Mecanim, supports many exciting new features, one of which is IK (short form for Inverse Kinematics). If you are unfamiliar with the term, IK allows one to define the target point of an animation and let the system figure out how to get there. Imagine you have a cup sitting on a table and a character that wants to pick it up. You could animate the character to bend over and pick it up; but, what if the character is slightly to the side? Or any number of other slight offsets that a player could cause, completely throwing off your animation? It is simply impractical to animate for every possibility. With IK, it hardly matters that the character is slightly off.

We just define the goal point for the hand and leave the animation of the arm to the IK system. It calculates how the arm needs to move in order to get the hand to the cup. Another fun use is making characters look at interesting things as they walk around a room: a guard could track the nearest person, the player's character could look at things that they can interact with, or a tentacle monster could lash out at the player without all the complex animation. This will be an exciting one to play with.

Mecanim – sync layers and additional curves

Sync layers, inside Mecanim, allow us to keep multiple sets of animation states in time with each other. Say you have a soldier that you want to animate differently based on how much health he has. When he is at full health, he walks around briskly. After a little damage to his health, the walk becomes more of a trudge. If his health is below half, a limp is introduced into his walk, and when he is almost dead he crawls along the ground. With sync layers, we can create one animation state machine and duplicate it to multiple layers. By changing the animations and syncing the layers, we can easily transition between the different animations while maintaining the
state machine.

The additional curves feature is simply the ability to add curves to your animation. This means we can control various values with the animation. For example, in the game world, when a character picks up its feet for a jump, gravity will pull them down almost immediately. By adding an extra curve to that animation, in Unity, we can control how much gravity is affecting the character, allowing them to actually be in the air when jumping. This is a useful feature for controlling such values alongside the animations, but you could just as easily create a script that holds and controls the curves.

The custom splash screen

Though pretty self-explanatory, it is perhaps not immediately evident why this feature is specified, unless you have worked with Unity before. When an application that is built in Unity initializes on any platform, it displays a splash screen. In Unity Basic, this will always be the Unity logo. By purchasing Unity Pro, you can substitute for the Unity logo with any image you want.

Real-time spot/point and soft shadows

Lights and shadows add a lot to the mood of a scene. This feature allows us to go beyond blob shadows and use realistic-looking shadows. This is all well and good if you have the processing space for it. However, most mobile devices do not. This feature should also never be used for static scenery; instead, use static lightmaps, which is what they are for.

However, if you can find a good balance between simple needs and quality, this could be the feature that creates the difference between an alright and an awesome game. If you absolutely must have real-time shadows, the directional light supports them and is the fastest of the lights to calculate. It is also the only type of light available to Unity Basic that supports real-time shadows.

HDR and tone mapping

HDR (short for high dynamic range) and tone mapping allow us to create more realistic lighting effects. Standard rendering uses values from zero to one to represent how much of each color in a pixel is on. This does not allow for a full spectrum of lighting options to be explored. HDR lets the system use values beyond this range and processes them using tone mapping to create better effects, such as a bright morning room or the bloom from a car window reflecting the sun. The downside of this feature is in the processor. The device can still only handle values between zero and one, so converting them takes time. Additionally, the more complex the effect, the more time it takes to render it. It would be surprising to see this used well on handheld devices, even in a simple game. Maybe the modern tablets could handle it.

Light probes

Light probes are an interesting little feature. When placed in the world, light probes figure out how an object should be lit. Then, as a character walks around, they tell it how to be shaded. The character is, of course, lit by the lights in the scene, but there are limits on how many lights can shade an object at once. Light probes do all the complex calculations beforehand, allowing for better shading at runtime. Again, however, there are concerns about processing power. Too little power and you won't get a good effect; too much and there will be no processing power left for playing the game.

Lightmapping with global illumination and area lights

All versions of Unity support lightmaps, allowing for the baking of complex static shadows and lighting effects. With the addition of global illumination and area lights, you can add another touch of realism to your scenes. However, every version of Unity also lets you import your own lightmaps. This means that you could use some other program to render the lightmaps and import them separately.

Static batching

This feature speeds up the rendering process. Instead of spending time grouping objects for faster rendering on each frame , this allows the system to save the groups generated beforehand. Reducing the number of draw calls is a powerful step towards making a game run faster. That is exactly what this feature does.

Render-to-texture effects

This is a fun feature, but of limited use. It allows you to use the output from a camera in your game as a texture. This texture could then, in its most simple form, be put onto a mesh and act as a surveillance camera. You could also do some custom post processing, such as removing the color from the world as the player loses their health. However, this option could become very processor-intensive.

Fullscreen post-processing effects

This is another processor-intensive feature that probably will not make it into your mobile game. However, you can add some very cool effects to your scene, such as adding motion blur when the player is moving really fast or a vortex effect to warp the scene as the ship passes through a warped section of space. One of the best effects is using the bloom effect to give things a neon-like glow.

Occlusion culling

This is another great optimization feature. The standard camera system renders everything that is within the camera's view frustum, the view space. Occlusion culling lets us set up volumes in the space our camera can enter. These volumes
are used to calculate what the camera can actually see from those locations. If there is a wall in the way, what is the point of rendering everything behind it? Occlusion culling calculates this and stops the camera from rendering anything behind
that wall.

Deferred rendering

If you desire the best looking game possible, with highly detailed lighting and shadows, this is a feature of interest for you. Deferred rendering is a multi-pass process for calculating your game's light and shadow detail. This is, however, an expensive process and requires a decent graphics card to fully maximize its use. Unfortunately, this makes it a little outside of our use for mobile games.

Stencil buffer access

Custom shaders can use the stencil buffer to create special effects by selectively rendering over specific pixels. It is similar to how one might use an alpha channel
to selectively render parts of a texture.

GPU skinning

This is a processing and rendering method by which the calculations for how a character or object appears, when using a skeleton rig, is given to the graphics card rather than getting it done by the central processor. It is significantly faster to render objects in this way. However, this is only supported on DirectX 11 and OpenGL ES 3.0, leaving it a bit out of reach for our mobile games.

Navmesh – dynamic obstacles and priority

This feature works in conjunction with the pathfinding system. In scripts, we can dynamically set obstacles, and characters will find their way around them. Being able to set priorities means that different types of characters can take different types of objects into consideration when finding their way around. For example, a soldier must go around the barricades to reach his target. The tank, however, could just crash through, should the player desire.

Native code plugins' support

If you have a custom set of code in the form of a Dynamic Link Library (DLL), this is the Unity Pro feature you need access to. Otherwise, the native plugins cannot be accessed by Unity for use with your game.

Profiler and GPU profiling

This is a very useful feature. The profiler provides tons of information about how much load your game puts on the processor. With this information, we can get right down into the nitty-gritties and determine exactly how long a script takes to process.

Script access to the asset pipeline

This is an alright feature. With full access to the pipeline, there is a lot of custom processing that can be done on assets and builds. The full range of possibilities is beyond the scope of this article. However, you can think of it as something that can make tint all of the imported textures slightly blue.

Dark skin

This is entirely a cosmetic feature. Its point and purpose are questionable. However, if a smooth, dark-skinned look is what you desire, this is the feature that you want. There is an option in the editor to change it to the color scheme used in Unity Basic. For this feature, whatever floats your boat goes.

Setting up the development environment

Before we can create the next great game for Android, we need to install a few programs. In order to make the Android SDK work, we will first install the Java Development Kit (JDK). Then we will install the Android SDK. After that, we will install Unity. We then have to install an optional code editor. To make sure everything is set up correctly, we will connect to our devices and take a look at some special strategies if the device is a tricky one. Finally, we will install Unity Remote, a program that will become invaluable in your mobile development.

Installing the JDK

Android's development language of choice is Java; so, to develop for it, we need a copy of the Java SE Development Kit on our computer. The process of installing the JDK is given in the following steps:

1. The latest version of the JDK can be downloaded from http://www.oracle.com/technetwork/java/javase/downloads/index.html. So open the site in a web browser, and you will be able to see the screen showed in the following screenshot:

   

2. Select Java Platform (JDK) from the available versions and you will be brought to a page that contains the license agreement and allows you
   to select the type of file you wish to download.
3. Accept the license agreement and select your appropriate Windows version from the list at the bottom. If you are unsure about which version to choose, then Windows x86 is usually a safe choice.
4. Once the download is completed, run the new installer.
5. After a system scan, click on Next two times, the JDK will initialize, and then click on the Next button one more time to install the JDK to the default location. It is as good there as anywhere else, so once it is installed, hit the Close button.

We have just finished installing the JDK. We need this so that our Android development kit will work. Luckily, the installation process for this keystone is short and sweet.

Installing the Android SDK

In order to actually develop and connect to our devices, we need to have installed the Android SDK. Having the SDK installed fulfills two primary requirements.
First, it makes sure that we have the bulk of the latest drivers for recognizing
devices. Second, we are able to use the Android Debug Bridge (ADB). ADB is the system used for actually connecting to and interacting with a device. The process
of installing the Android SDK is given in the following steps:

1. The latest version of the Android SDK can be found at http://developer.android.com/sdk/index.html, so open a web browser and go to the given site.
2. Once there, scroll to the bottom and find the SDK Tools Only section. This is where we can get just the SDK, which we need to make Android games with Unity, without dealing with the fancy fluff of the Android Studio.
3. We need to select the .exe package with (Recommended) underneath it (as shown in the following screenshot):

   

4. You will then be sent to a Terms and Conditions page. Read it if you prefer, but agree to it to continue. Then hit the Download button to start downloading the installer.
5. Once it has finished downloading, start it up.
6. Hit the first Next button and the installer will try to find an appropriate version of the JDK. You will come to a page that will notify you about not finding the JDK if you do not have it installed.
7. If you skipped ahead and do not have the JDK installed, hit the Visit java.oracle.com button in the middle of the page and go back to the previous section for guidance on installing it. If you do have it, continue with the process.
8. Hitting Next again will bring you to a page that will ask you about the person for whom you are installing the SDK .
9. Select Install for anyone using this computer because the default install location is easier to get to for later purposes.
10. Hit Next twice, followed by Install to install the SDK to the default location.
11. Once this is done, hit Next and Finish to complete the installation of the Android SDK Manager.
12. If Android SDK Manager does not start right away, start it up. Either way, give it a moment to initialize. The SDK Manager makes sure that we have the latest drivers, systems, and tools for developing with the Android platform. However, we have to actually install them first (which can be done from the following screen):

    

13. By default, the SDK manager should select a number of options to install. If not, select the latest Android API (Android L (API 20) as of the time of writing this article), Android Support Library and Google USB Driver found in Extras. Be absolutely sure that Android SDK Platform-tools is selected. This will be very important later. It actually includes the tools that we need to connect to our device.
14. Once everything is selected, hit Install packages at the bottom-right corner.
15. The next screen is another set of license agreements. Every time a component is installed or updated through the SDK manager, you have to agree to the license terms before it gets installed. Accept all of the licenses and hit Install to start the process.
16. You can now sit back and relax. It takes a while for the components to be downloaded and installed. Once this is all done, you can close it out. We have completed the process, but you should occasionally come back to it. Periodically checking the SDK manager for updates will make sure that you are using the latest tools and APIs.

The installation of the Android SDK is now finished. Without it, we would be completely unable to do anything on the Android platform. Aside from the long
wait to download and install components, this was a pretty easy installation.

Installing Unity 3D

Perform the following steps to install Unity:

1. The latest version of Unity can be found at http://www.unity3d.com/unity/download. As of the time of writing this article, the current version is 5.0.
2. Once it is downloaded, launch the installer and click on Next until you reach the Choose Components page, as shown in the following screenshot:

   

3. Here, we are able to select the features of Unity installation:
   •      Example Project: This is the current project built by Unity to show off some of its latest features. If you want to jump in early and take a look at what a complete Unity game can look like, leave this checked.
   •      Unity Development Web Player: This is required if you plan on developing browser applications with Unity. As this article is focused on Android development, it is entirely optional. It is, however, a good one to check. You never know when you may need a web demo and since it is entirely free to develop for the web using Unity, there is no harm in having it.
   •      MonoDevelop: It is a wise choice to leave this option unchecked. There is more detail in the next section, but it will suffice for now to say that it just adds an extra program for script editing that is not nearly as useful as it should be.
4. Once you have selected or deselected your desired options, hit Next. If you wish to follow this article, note that we will uncheck MonoDevelop and leave the rest checked.
5. Next is the location of installation. The default location works well, so hit Install and wait. This will take a couple of minutes, so sit back, relax, and enjoy your favorite beverage.
6. Once the installation is complete, the option to run Unity will be displayed. Leave it checked and hit Finish. If you have never installed Unity before, you will be presented with a license activation page (as shown in the following screenshot):

   

7. While Unity does provide a feature-rich, free version, in order to follow the entirety of this article, one is required to make use of some of the Unity Pro features. At https://store.unity3d.com, you have the ability to buy a variety of licenses. Once they are purchased, you will receive an e-mail containing your new license key. Enter that in the provided text field.
8. If you are not ready to make a purchase, you have two alternatives. We will go over how to reset your license in the Building a simple application section later in the article. The alternatives are as follows:
   •      The first alternative is that you can check the Activate the free version of Unity checkbox. This will allow you to use the free version of Unity. As discussed earlier, there are many reasons to choose this option. The most notable at the moment is cost.
   •      Alternatively, you can select the Activate a free 30-day trial of Unity Pro option. Unity offers a fully functional, one-time installation and a free 30-day trial of  Unity Pro. This trial also includes the Android Pro add-on. Anything produced during the 30 days is completely yours, as if you had purchased a full Unity Pro license. They want you to see how great it is, so you will come back and make a purchase. The downside is that the Trial Version watermark will be constantly displayed at the corner of the game. After the 30 days, Unity will revert to the free version. This is a great option, should you choose to wait before making a purchase.
9. Whatever your choice is, hit OK once you have made it.
10. The next page simply asks you to log in with your Unity account. This will be the same account that you used to make your purchase. Just fill out the fields and hit OK.
11. If you have not yet made a purchase, you can hit Create Account and have it ready for when you do make a purchase.
12. The next page is a short survey on your development interests. Fill it out and hit OK or scroll straight to the bottom and hit Not right now.
13. Finally, there is a thank you page. Hit Start using Unity.
14. After a short initialization, the project wizard will open and we can start creating the next great game. However, there is still a bunch of work to do to connect the development device. So for now, hit the X button in the top-right corner to close the project wizard. We will cover how to create a new project in the Building a simple application section later on.

We just completed installing Unity 3D. We also had to make a choice about licenses. The alternatives, though, will have a few shortcomings. You will either not have full access to all of the features or be limited to the length of the trial period while making due with a watermark in your games.

The optional code editor

Now a choice has to be made about code editors. Unity comes with a system called MonoDevelop. It is similar in many respects to Visual Studio. And like Visual Studio, it adds many extra files and much girth to a project, all of which it needs to operate. All this extra girth makes it take an annoying amount of time to start up, before one can actually get to the code.

Technically, you can get away with a plain text editor, as Unity doesn't really care. This article recommends using Notepad++, which is found at http://notepad-plus-plus.org/download. It is free to use and it is essentially Notepad with code highlighting. There are several fancy widgets and add-ons for Notepad++ that add even greater functionality to it, but they are not necessary for following this article. If you choose this alternative, installing Notepad++ to the default location will work just fine.

Connecting to a device

Perhaps the most annoying step in working with Android devices is setting up the connection to your computer. Since there are so many different kinds of devices, it can get a little tricky at times just to have the device recognized by your computer.

A simple device connection

The simple device connection method involves changing a few settings and a little work in the command prompt. It may seem a little scary, but if all goes well you will be connected to your device shortly:

1. The first thing you need to do is turn on the phone's Developer options. In the latest version of Android, these have been hidden. Go to your phone's settings page and find the About phone page.
2. Next, you need to find the Build number information slot and tap it several times. At first, it will appear to do nothing, but it will shortly display that you need to press the button a few more times to activate the Developer options. The Android team did this so that the average user does not accidentally make changes.
3. Now go back to your settings page and there should be a new Developer options page; select it now. This page controls all of the settings you might need to change while developing your applications.
4. The only checkbox we are really concerned with checking right now is USB debugging. This allows us to actually detect our device from the development environment.
5. If you are using Kindle, be sure to go into Security and turn on Enable ADB as well.
   

   There are several warning pop-ups that are associated with turning on these various options. They essentially amount to the same malicious software warnings associated with your computer. Applications with immoral intentions can mess with your system and get to your private information. All these settings need to be turned on if your device is only going to be used for development. However, as the warnings suggest, if malicious applications are a concern, turn them off when you are not developing.

6. Next, open a command prompt on your computer. This can be done most easily by hitting your Windows key, typing cmd.exe, and then hitting Enter.
7. We now need to navigate to the ADB commands. If you did not install the SDK to the default location, replace the path in the following commands with the path where you installed it.

   If you are running a 32-bit version of Windows and installed the SDK to the default location, type the following in the command prompt:

   cd c:\program files\android\android-sdk\platform-tools

   If you are running a 64-bit version, type the following in the command prompt:

   cd c:\program files (x86)\android\android-sdk\platform-tools

8. Now, connect your device to your computer, preferably using the USB cable that came with it.
9. Wait for your computer to finish recognizing the device. There should be a Device drivers installed type of message pop-up when it is done.
10. The following command lets us see which devices are currently connected and recognized by the ADB system. Emulated devices will show up as well. Type the following in the command prompt:

    adb devices

11. After a short pause for processing, the command prompt will display a list of attached devices along with the unique IDs of all the attached devices. If this list now contains your device, congratulations! You have a developer-friendly device. If it is not completely developer-friendly, there is one more thing that you can try before things get tricky.
12. Go to the top of your device and open your system notifications. There should be one that looks like the USB symbol. Selecting it will open the connection settings. There are a few options here and by default Android selects to connect the Android device as a Media Device.
13. We need to connect our device as a Camera. The reason is the connection method used. Usually, this will allow your computer to connect.

We have completed our first attempt at connecting to our Android devices. For most, this should be all that you need to connect to your device. For some, this process is not quite enough. The next little section covers solutions to resolve the issue for connecting trickier devices.

For trickier devices, there are a few general things that we can try; if these steps fail to connect your device, you may need to do some special research.

1. Start by typing the following commands. These will restart the connection system and display the list of devices again:

   adb kill-server
   adb start-server
   adb devices

2. If you are still not having any luck, try the following commands. These commands force an update and restart the connection system:

   cd ../tools
   android update adb
   cd ../platform-tools
   adb kill-server
   adb start-server
   adb devices

3. If your device is still not showing up, you have one of the most annoying and tricky devices. Check the manufacturer's website for data syncing and management programs. If you have had your device for quite some time, you have probably been prompted to install this more than once. If you have not already done so, install the latest version even if you never plan on using it. The point is to obtain the latest drivers for your device, and this is the easiest way.
4. Restart the connection system again using the first set of commands and cross your fingers!
5. If you are still unable to connect, the best, professional recommendation that can be made is to google for the solution to your problem. Conducting a search for your device's brand with adb at the end should turn up a step-by-step tutorial that is specific to your device in the first couple of results. Another excellent resource for finding out all about the nitty-gritties of Android devices can be found at http://www.xda-developers.com/.

Some of the devices that you will encounter while developing will not connect easily. We just covered some quick steps and managed to connect these devices. If we could have covered the processes for every device, we would have. However, the variety of devices is just too large and the manufacturers keep making more.

Unity Remote

Unity Remote is a great application created by the Unity team. It allows developers to connect their Android-powered devices to the Unity Editor and provide mobile inputs for testing. This is a definite must for any aspiring Unity and Android developer. If you are using a non-Amazon device, acquiring Unity Remote is quite easy. At the time of writing this article, it could be found on Google Play at https://play.google.com/store/apps/details?id=com.unity3d.genericremote. It is free and does nothing but connects your Android device to the Unity Editor, so the app permissions are negligible. In fact, there are currently two versions of Unity Remote. To connect to Unity 4.5 and later versions, we must use Unity Remote 4.

If, however, you like the ever-growing Amazon market or seek to target Amazon's line of Android devices, adding Unity Remote will become a little trickier. First, you need to download a special Unity Package from the Unity Asset Store. It can be found at https://www.assetstore.unity3d.com/en/#!/content/18106. You will need to import the package into a fresh project and build it from there. Import the package by going to the top of Unity, navigate to Assets | Import Package | Custom Package, and then navigate to where you saved it. In the next section, we will build a simple application and put it on our device. After you have imported the package, follow along from the step where we open the Build Settings window, replacing the simple application with the created APK.

Building a simple application

We are now going to create a simple Hello World application. This will familiarize you with the Unity interface and how to actually put an application on your device.

Hello World

To make sure everything is set up properly, we need a simple application to test with and what better to do that with than a Hello World application? To build the application, perform the following steps:

1. The first step is pretty straightforward and simple: start Unity.
2. If you have been following along so far, once this is done you should see a screen resembling the next screenshot. As the tab might suggest, this is the screen through which we open our various projects. Right now, though, we are interested in creating one; so, select New Project from the top-right corner and we will do just that:

   

3. Use the Project name* field to give your project a name; Ch1_HelloWorld fits well for a project name. Then use the three dots to the right of the Location* field to choose a place on your computer to put the new project. Unity will create a new folder in this location, based on the project name, to store your project and all of its related files:

   

4. For now, we can ignore the 3D and 2D buttons. These let us determine the defaults that Unity will use when creating a new scene and importing new assets. We can also ignore the Asset packages button. This lets you select from the bits of assets and functionality that is provided by Unity. They are free for you to use in your projects.
5. Hit the Create Project button, and Unity will create a brand-new project for us.

   The following screenshot shows the windows of the Unity Editor:

   

6. The default layout of Unity contains a decent spread of windows that are needed to create a game:
   •      Starting from the left-hand side, Hierarchy contains a list of all the objects that currently exist in our scene. They are organized alphabetically and are grouped under parent objects.
   •      Next to this is the Scene view. This window allows us to edit and arrange objects in the 3D space. In the top left-hand side, there are two groups of buttons. These affect how you can interact with the Scene view.
   •      The button on the far left that looks like a hand lets you pan around when you click and drag with the mouse.
   •      The next button, the crossed arrows, lets you move objects around. Its behavior and the gizmo it provides will be familiar if you have made use of any modeling programs.
   •      The third button changes the gizmo to rotation. It allows you to
     rotate objects.
   •      The fourth button is for scale. It changes the gizmo as well.
   •      The fifth button lets you adjust the position and the scale based on the bounding box of the object and its orientation relative to how
     you are viewing it.
   •      The second to last button toggles between Pivot and Center. This will change the position of the gizmo used by the last three buttons to be either at the pivot point of the selected object, or at the average position point of all the selected objects.
   •      The last button toggles between Local and Global. This changes whether the gizmo is orientated parallel with the world origin or rotated with the selected object.
   •      Underneath the Scene view is the Game view. This is what is currently being rendered by any cameras in the scene. This is what the player will see when playing the game and is used for testing your game. There are three buttons that control the playback of the Game view in the upper-middle section of the window.
   •      The first is the Play button. It toggles the running of the game. If you want to test your game, press this button.
   •      The second is the Pause button. While playing, pressing this button will pause the whole game, allowing you to take a look at the game's current state.
   •      The third is the Step button. When paused, this button will let you progress through your game one frame at a time.
   •      On the right-hand side is the Inspector window. This displays information about any object that is currently selected.
   •      In the bottom left-hand side is the Project window. This displays all of the assets that are currently stored in the project.
   •      Behind this is Console. It will display debug messages, compile errors, warnings, and runtime errors.
7. At the top, underneath Help, is an option called Manage License.... By selecting this, we are given options to control the license. The button descriptions cover what they do pretty well, so we will not cover them
   in more detail at this point.
8. The next thing we need to do is connect our optional code editor. At
   the top, go to Edit and then click on Preferences..., which will open the following window:

   

9. By selecting External Tools on the left-hand side, we can select other software to manage asset editing.
10. If you do not want to use MonoDevelop, select the drop-down list to the right of External Script Editor and navigate to the executable of Notepad++, or any other code editor of your choice.
11. Your Image application option can also be changed here to Adobe Photoshop or any other image-editing program that you prefer,
    in the same way as the script editor.
12. If you installed the Android SDK to the default location, do not worry about it. Otherwise, click on Browse... and find the android-sdk folder.
13. Now, for the actual creation of this application, right-click inside your
    Project window.
14. From the new window that pops up, select Create and C# Script from
    the menu.
15. Type in a name for the new script (HelloWorld will work well) and hit Enter twice: once to confirm the name and once to open it.
    

    In this article, this will be a simple Hello World application. Unity supports C#, JavaScript, and Boo as scripting languages. For consistency, this article will be using C#. If you, instead, wish to use JavaScript for your scripts, copies of all of the projects can be found with the other resources for this article, under a _JS suffix for JavaScript.

16. Every script that is going to attach to an object extends the functionality of the MonoBehaviour class. JavaScript does this automatically, but C# scripts must define it explicitly. However, as you can see from the default code in the script, we do not have to worry about setting this up initially; it is done automatically. Extending the MonoBehaviour class lets our scripts access various values of the game object, such as the position, and lets the system automatically call certain functions during specific events in the game, such as the Update cycle and the GUI rendering.
17. For now, we will delete the Start and Update functions that Unity insists on including in every new script. Replace them with a bit of code that simply renders the words Hello World in the top-left corner of the screen; you can now close the script and return to Unity:

    public void OnGUI() {
    GUILayout.Label("Hello World");
    }

18. Drag the HelloWorld script from the Project window and drop it on the Main Camera object in the Hierarchy window. Congratulations! You have just added your first bit of functionality to an object in Unity.
19. If you select Main Camera in Hierarchy, then Inspector will display all of the components attached to it. At the bottom of the list is your brand-new HelloWorld script.
20. Before we can test it, we need to save the scene. To do this, go to File at the top and select Save Scene. Give it the name HelloWorld and hit Save. A new icon will appear in your Project window, indicating that you have saved the scene.
21. You are now free to hit the Play button in the upper-middle section of the editor and witness the magic of Hello World.
22. We now get to build the application. At the top, select File and then click on Build Settings....
23. By default, the target platform is PC. Under Platform, select Android and hit Switch Platform in the bottom-left corner of the Build Settings window.
24. Underneath the Scenes In Build box, there is a button labeled Add Current. Click on it to add our currently opened scene to the build. Only scenes that are in this list and checked will be added to the final build of your game. The scene with the number zero next to it will be the first scene that is loaded when the game starts.
25. There is one last group of things to change before we can hit the Build button. Select Player Settings... at the bottom of the Build Settings window.
26. The Inspector window will open Player Settings (shown in the following screenshot) for the application. From here, we can change the splash screen, icon, screen orientation, and a handful of other technical options:

    

27. At the moment, there are only a few options that we care about. At the top, Company Name is the name that will appear under the information about the application. Product Name is the name that will appear underneath the icon on your Android device. You can largely set these to anything you want, but they do need to be set immediately.
28. The important setting is Bundle Identifier, underneath Other Settings and Identification. This is the unique identifier that singles out your application from all other applications on the device. The format is com.CompanyName.ProductName, and it is a good practice to use the same company name across all of your products. For this article, we will be using com.TomPacktAndBegin.Ch1.HelloWorld for Bundle Identifier and opt to use an extra dot (period) for the organization.

    

29. Go to File and then click on Save again.
30. Now you can hit the Build button in the Build Settings window.
31. Pick a location to save the file, and a file name ( Ch1_HelloWorld.apk works well). Be sure to remember where it is and hit Save.
32. If during the build process Unity complains about where the Android SDK is, select the android-sdk folder inside the location where it was installed. The default would be C:\Program Files\Android\android-sdk for a 32-bit Windows system and C:\Program Files (x86)\Android\android-sdk for a 64-bit Windows system.
33. Once loading is done, which should not be very long, your APK will have been made and we are ready to continue.
34. We are through with Unity for this article. You can close it down and open a command prompt.
35. Just as we did when we were connecting our devices, we need to navigate to the platform-tools folder in order to connect to our device. If you installed the SDK to the default location, use:
    •      For a 32-bit Windows system:

      cd c:\program files\android\android-sdk\platform-tools

    •      For a 64-bit Windows system:

      cd c:\program files (x86)\android\android-sdk\platform-tools

36. Double-check to make sure that the device is connected and recognized by using the following command:

    adb devices

37. Now we will install the application. This command tells the system to install an application on the connected device. The -r indicates that it should override if an application is found with the same Bundle Identifier as the application we are trying to install. This way you can just update your game as you develop, rather than uninstalling before installing the new version each time you need to make an update. The path to the .apk file that you wish to install is shown in quotes as follows:

    adb install -r "c:\users\tom\desktop\packt\book\ch1_helloworld.apk"

38. Replace it with the path to your APK file; capital letters do not matter, but be sure to have all the correct spacing and punctuations.
39. If all goes well, the console will display an upload speed when it has finished pushing your application to the device and a success message when it has finished the installation. The most common causes for errors at this stage are not being in the platform-tools folder when issuing commands and not having the correct path to the .apk file, surrounded by quotes.
40. Once you have received your success message, find the application on your phone and start it up.
41. Now, gaze in wonder at your ability to create Android applications with the power of Unity.

We have created our very first Unity and Android application. Admittedly, it was just a simple Hello World application, but that is how it always starts. This served very well for double-checking the device connection and for learning about the build process without all the clutter from a game.

If you are looking for a further challenge, try changing the icon for the application. It is a fairly simple procedure that you will undoubtedly want to perform as your game develops. How to do this was mentioned earlier in this section, but, as a reminder, take a look at Player Settings. Also, you will need to import an image. Take a look under Assets, in the menu bar, to know how to do this.

Summary

There were a lot of technical things in this article. First, we discussed the benefits and possibilities when using Unity and Android. That was followed by a whole lot of installation; the JDK, the Android SDK, Unity 3D, and Unity Remote. We then figured out how to connect to our devices through the command prompt. Our first application was quick and simple to make. We built it and put it on a device.

Resources for Article:

Further resources on this subject:

• What's Your Input? [article]
• That's One Fancy Hammer! [article]
• Saying Hello to Unity and Android [article]