3D Platformer Tutorial

Building a 3D Platform Game in Unity 2.0

Introduction

With its myriad features, including heightmapped

terrains, native networking support,

complete physics integration and scripting, Unity can be daunting for newcomers,

but mastering its many tools is infinitely rewarding.

This tutorial will walk you through the process of building a complete 3D platform

game level with a thirdperson

perspective view. This includes everything from player

controls, collision detection, some advanced scripting, blob shadows, basic AI, adding

a game HUD, cutscenes

and audio spot effects.

What you will learn

This tutorial focuses on the technical side of building a game in Unity, covering the

following:

• Character Controllers

• Projectors

• Audio Listeners, Audio Sources & Audio Clips

• Multiple Cameras (and how to switch between them)

• UnityGUI scripting system

• Colliders

• Messages & events

Unity is a powerful tool for game

development, suitable for many

game genres, from firstperson

shooters to puzzle games.

• Lighting

• Particle systems

• Blob shadows

• Scripting (AI, state machines, player controls)

This tutorial will show how these features can be used together to create a game.

What you should already know

This tutorial makes extensive use of scripting so you should be familiar with at least

one of the supported scripting languages: JavaScript, C# or Boo. (JavaScript is used for

the scripts in this tutorial.)

It is also assumed that you are familiar with Unity’s interface and know how to perform

basic operations, such as positioning an asset in a scene, adding Components to a

GameObject, and editing properties in the Inspector.

Project Organization

Unity does not attempt to force a particular way of organizing your project's assets.

You may prefer organizing your assets by asset type, with separate folders for, say,

"Textures", "Models", "Sound effects" and so on. At Unity Technologies, we have

found this works well for smaller projects. For more complex projects, our users generally

recommend organizing assets by function, perhaps grouping them under folders

such as "Player", "Enemies", "Props", "Scenery", and so on.

This tutorial’s project was worked on by a number of team members and grew organically

to reflect their different conventions and styles. In the interests of authenticity,

we have decided to leave the project's organization as it was as this is more representative

of a 'smaller' project's organization and structure.

Abstract GameObjects & Components

Unity's design places each scene's assets at the center of the development process. This

makes for a very visual approach to game development, with most of the work involving

dragging and dropping. This is ideal for the bulk of level design work, but not all

assets can be displayed in this way. Some assets are abstract rather than visual objects,

so they are either represented by abstract icons and wireframe gizmos e.

g. Audio

Sources and Lights or

are not displayed at all within the Scene View. Scripts fall into

this latter category.

Scripts define how assets and GameObjects in a Unity Scene interact with each other

and this interactivity is at the core of all games. For this reason, it is usually a good

plan to keep informative notes inside your scripts.

This tutorial will assume you can read the provided scripts and understand the many

comments liberally sprinkled throughout them. However, when a particular scripting

technique or concept is important, we will cover it in detail.

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The scripts are documented through the use of extensive comments and have also

been designed to be as selfexplanatory

as possible in their design. We encourage you

to read through the scripts as we introduce them in this tutorial, studying their workings.

Feel free to experiment!

Files

The most uptodate

files for this project can be downloaded from:

http://unity3d.com/support/resources/tutorials/3DPlatformProject.zip

The “Scenes” folder contains the final result: a main menu Scene, a game over Scene

and a Scene containing the completed game level.

This tutorial assumes you already know basic Unity controls, such as positioning objects

in a scene, so the first starting point Scene already has the basic scenery and some

props in place.

Typographical Conventions

This is a long tutorial containing a lot of information. To make it easier to follow,

some simple conventions are used:

Background & Tangents

Text in boxes like these contains additional information that may help clarify the main

text.

Scripting code will appear as shown below:

// This is some script code.

Function Update()

{

DoSomething();

}

NOTE The scripts included in the tutorial include plenty of comments and are designed

to be easy to follow. These comments are usually omitted in the code

fragments in the tutorial text to save space.

Actions you need to perform within Unity are shown like this:

Click on this;

Then this;

Then click Play.

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Script names, assets, menu items or Inspector Properties are shown in boldface text.

Conversely, a monospace font is used for script functions and event names, such as

the Update() function in the script example above.

Unity Conventions

Unity is a unique development system. Most developers will be used to working in a

code editor, spending 90% of their time editing code and even writing code to load

up and use assets. Unity is different: It is assetcentric

rather than codecentric,

placing

the focus on the assets in much the same way as a 3D modeling application. For this

reason, it is worth understanding the key conventions and terminology unique to

Unity development:

Projects

A game built in Unity will consist of a Project. This contains all your project’s elements,

such as models, scripts, levels, menus, etc. Usually, a single Project file will contain all

the elements for your game. When you start Unity 2, the first thing it does is open a

Project file. (If you have only just installed it, this will be the Project file containing the

Island Demo.)

Scenes

Each Project contains one or more documents called Scenes. A single Scene will contain

a single game level, but major userinterface

elements, such as game menus,

gameover

sequences or major cutscenes

may also live in their own Scene files. Complex

games may even use entire Scenes just for initialization purposes. Thus all levels

in a game will most likely be Scenes, but not every Scene will necessarily be a game

level.

GameObjects, Components, Assets & Prefabs

Key to understanding Unity is the relationship between a GameObject and a Component.

GameObjects

A GameObject is the fundamental building block in Unity. A GameObject is a container

for different pieces of functionality called Components. A GameObject almost

always contains more than one Component. All GameObjects contain a Transform

Component, which defines its position and orientation.

GameObject Hierarchies

The real power of the GameObject is its ability to contain other GameObjects, acting

much like a folder in OS X’s Finder. This allows hierarchical organization of GameObjects,

so a complex model or a complete lighting rig can be defined under a single

parent GameObject. (In fact, most models will appear in Unity as a hierarchy of

GameObjects because this reflects how they are defined in the modeling package.) A

GameObject defined inside another GameObject is considered a child GameObject.

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Components

Components are the building blocks of GameObjects. Without them, the GameObject

won’t do anything interesting.

A Component may represent visible entities, such as meshes, materials, terrain data or

a particle system. Other Component types are more abstract, such as Cameras and

Lights, which do not have a physical model representing them; instead, you will see an

icon and some wireframe

guidelines illustrating their key settings.

A Component is always attached to a GameObject; it cannot live alone. Multiple Components

can be attached to the same GameObject. GameObjects can support multiple

Components of certain types―a GameObject can contain any number of scripts, for

example. But others, such as those used to define particle systems, are exclusive and

can only appear once in any single GameObject. For example, if you want to define

multiple particle systems, you would normally use a hierarchy of GameObjects, each

containing its own set of particle system Components.

Assets

All your imported Assets appear in the Project Pane and they can be almost anything:

a simple material or texture, audio files, or even a complete, prefabricated GameObject

(known as a “Prefab”).

For example, a player character Prefab could be defined as a single Asset, containing

the model and its associated animations. It could also contain script Components,

audio clips and any other Components it needs to function, so you could simply drag it

into a Scene and instantly have a fully operational avatar.

Custom Icons & Gizmos

You can tell Unity to display custom icons and other visual information for your Assets

if you wish. We will see an example of this in the next chapter.

Your project’s Assets are shown in the Project Pane. When you drop one into your

Scene, it appears in the Hierarchy Pane, which defines the content of the Scene. (A

Scene is the equivalent of the stage in a theater. It can be a level, a menu, a multiplayer

game lobby whatever

you wish.) The Project Pane is retained across all Scenes

in your Project.

Prefabs

A Prefab is an Asset which has been defined as a template. It is to Unity what a template

document is to a word processing application. When you place a Prefab into

your Scene, Unity places a link to the Prefab into the Hierarchy Pane, not a complete

copy. This is called instantiation. Each link you make is referred to as an instance of

the Prefab.

If you click on a Prefab in your Project Pane and tweak its settings, you will find that

those changes are instantly reflected in all the instances in your Scene. This makes Pre9

fabs ideal for many reusable

elements, such as bullets, enemies and so on. If you find

your enemy isn’t behaving correctly, you only need to adjust the script or settings in

the original Prefab instead of editing each one in the Scene individually.

However, if you need to adjust a couple of settings in a specific instance of a Prefab,

you may do this too: these changes will only affect that particular instance.

Prefabs are displayed in blue text in both the Project and Hierarchy Pane.

NOTE A Prefab instance cannot have additional Components added to it as doing so

will break the link to the original Prefab. Unity will warn you if you try and do

this. Unity will, however, allow you to update the original Prefab with such

changes after the link is broken.

Acknowledgments

This tutorial could not have been produced without the following people:

David Helgason, Joachim Ante, Tom Higgins, Sam Kalman, Keli Hlodversson, Nicholas

Francis, Aras Pranckevičius, Forest Johnson and, of course, Ethan Vosburgh who produced

the beautiful assets for this tutorial.