Unity Components: Scripts

One of the things I really enjoy about Unity is the way the engine handles objects in the game world. Everything you add to your game scene is inherently a Game Object, which is a data type built into the engine. The interesting part is the ability to attach different Components to any Game Object. For example, going to GameObject > Create Other > Cube will spawn a cube object in the scene with four pre-defined Components attached to it: Transform, Mesh Filter, Box Collider, and Mesh Renderer. But really it’s the same thing as if you had gone to GameObject > Create Empty and added those Components to the newly-created object manually. If you need to, you can even remove most of the Components. This allows a wide range of customization options for game objects within Unity.

Scripts are also considered Components that can be attached directly to Game Objects. They essentially provide the developer the ability to manipulate an object by giving allowing more control over it via a programming interface. From within a script, the developer can access any part of its parent Game Object, including its other Components and their properties.

Since all components except scripts have pre-determined names, accessing them through a script requires the knowledge of each Component’s corresponding property name within code. The entire list, along with every Component’s description, can be found in the official Unity documentation, but here they are in a nutshell:

  • Transform is accessed as transform
  • Rigid Body is accessed as rigidbody
  • Renderer is accessed as renderer
  • Camera is accessed as camera
  • Light is accessed as light
  • Animation is accessed as animation
  • Collider is accessed as collider
Script Example
Accessing the Mesh Renderer Component attached to this script's Game Object when the object is created at run-time.

In order to access another script on the current object, you’ll have to refer to the name of the script directly by passing it to the GetComponent method. For example, if I want to access the “CharacterController” script but I’m currently in the “Main” script, I would use GetComponent(CharacterController).propertyName.

Accessing Other Scripts
Use the other script's name in order to access it.

In the example above, you can see references to several components and properties within the thisOre GameObject. Its x- and y-coordinates can be found within the Transform Component attached to the object. Those properties are set to variables that have been determined in other locations, one of which is the height variable that is only accessible by retrieving it from thisOre’s “ICOre” script.

Scripts can access not only the Components within the Game Object to which they are attached, but also any Game Object in the scene. This essentially allows the developer full control over any aspect of their game, through code. There are many ways to access other objects. So far I’ve found that GameObject.Find and FindObjectOfType have been reliable for accessing specific objects and scripts, respectively.

Accessing Other Objects
Any object or script can be referenced easily when needed.

Being able to reference the properties and methods of Components within a script’s corresponding Game Object, as well as the properties and methods within other objects’ Components is vital for maintaining full control over your project. Luckily, Unity makes such things very easy to do, with clear instructions right on their site.

Finally, one of the best things about Unity’s scripting is that it allows any of three languages: JavaScript, C#, or Boo (a dialect of Python). As I come from primarily an ActionScript 3.0 background, it was a great surprise to find that writing in JavaScript is almost identical to the way I do things in AS3. I would imagine that other programmers who are interested in Unity but could be wary of having to learn an entirely new language may breathe a similar sigh of relief.

The Decision to Use Unity, Part 2

So, what makes Unity better than the other game engines, in our eyes? That’s what I’d like to go over in this post. There are several reasons Matt and I chose Unity as our game engine for Jestermen’s first project, “The Infernicore”.

Its Simplicity

Unity's UI
Relatively simple, but effective!

Unlike quite a few other pieces of software I’ve used, Unity’s interface is exceedingly simple. It is intuitive, easy to use, and allows the user all of the options he or she needs without requiring row upon row of toolbars and menus. In fact, there are only five main panels within Unity: Scene, Game, Hierarchy, Project, and Inspector. The Scene panel displays the game assets during construction; easily navigable using common keyboard/mouse controls (such as holding Alt + dragging with left click to rotate the scene). The Game panel offers a view of the game as the user would see it; in fact, by simply pressing the play button at the top of the interface, one can immediately begin playing the game. The Hierarchy panel lists all assets that are currently in the scene. The Project panel displays every file that is in the Assets folder of the project for quick access to dropping any of them into the scene directly. And the Inspector panel simply waits for you to click on something, at which point it will display all properties associated with the clicked object. Of course, there are other buttons and menus, but the point is that none of them are vital to the core development process, which is why it was a smart move to keep them hidden until they’re needed.

Its Target Platforms

Unity 3D version 3.5 offers a new publishing option which has a potential that is quite difficult to overstate. Its ability to build projects directly into SWF files that automatically run in Adobe Flash Player means developers who want to distribute their content through the web no longer have to worry about whether sites support the Unity Web Player. And now that Flash Player 11 has a new 3D graphics rendering engine, the fact that Unity creates 3D content is also not a problem.

Unity 3D Build Settings
So many options, so few clicks!

Flash Player support isn’t the only upside to Unity’s publishing potential, however. The fact that it can build to so many different platforms without modifying a single line of code, as well as the ability to switch between target platforms with the click of a button (literally, just one button!) should be even further cause for excitement. PC standalone, Mac standalone, Flash Player, Unity Player, Android, iOS, XBox 360, PlayStation 3, and Wii build options are all supported.

 

Its Robustness

As if simplicity and distribution potential weren’t enough, Unity comes packed with enough features to make one wonder exactly why the entire program doesn’t require a purchased license in order to use it. For example, its built-in physics engine means developers don’t have to spend time messing with things like gravity and collision detection unless they really want to. Simply use the included script editor to apply a script with an OnCollisionEnter function. If more information is desired, the full documentation for every aspect of Scripting in Unity can be found on Unity’s website. JavaScript, C#, and Boo are the supported scripting languages. For the full list of features, look here.

What’s the downside to all of this? Surely it sounds too good to be true. I thought the same thing myself. And while I’m not exactly an expert Unity developer yet (I’ve only been using it for a couple months at most), I think I’ve seen enough to know that the pros greatly outweigh the cons. But as far as I can tell there is only one major con: the cost. Most features are present in the basic version, but building to anything except PC/Mac standalone and the Web Player will require a fee of some kind. Building to Android or iOS requires a $400 license for each. The Pro license costs $1500. And when version 3.5 comes out of public beta, publishing for the Flash Player will also require a fee. Jestermen encourages anyone to snag the basic version and actually develop something first, though. That’s what we’ve done, and we fell in love with the program. Try it and see!