Overview

In this and the next two lessons, you will be working with the Unity3D game engine, simply referred to as Unity throughout the rest of the course. Unity is a rather complex software system for building 3D (as well as 2D) computer games, and other 3D applications. Hence, we will only be able to scratch the surface of all the things that can be done with Unity in this course. Nevertheless, you will learn quite a few useful skills related to constructing 3D and VR applications in Unity dealing with virtual environments. Furthermore, you will become familiarized with C# programming (the main programming language used in this engine) through a series of exercises that guide you on developing your first interactive experience in a game engine.

This lesson will begin with an overview to acquaint you with the most important concepts and the interface of Unity. It will cover basic project management in Unity, the Project Editor interface, manipulation of a 3D scene, importing 3D models and other assets, and building a stand-alone Windows application from a Unity project. Moreover, you will learn how to create a very simple “roll-the-ball” 3D game using C#, which will prepare you for more advanced interaction mechanics we will be implementing in the next lessons.

Learning Outcomes

By the end of this lesson, you should be able to:

• Explain the role of interaction for 3D/VR projects and the role of game engines for enabling access to 3D models
• Create 3D projects in Unity3D, import 3D models, and understand the basic concepts and interface elements of the Unity editor
• Manipulate scenes and add script components to game objects
• Import custom Unity packages into a unity project
• Develop a basic understanding of the physics engine of Unity (e.g. gravity, collision detection)
• Run projects inside Unity and build stand-alone applications from them
• Have a basic understanding of how to make an experience come “alive” by programming behaviours for game objects

Lesson Roadmap

Questions?

If you have any questions, please post them to our "General and Technical Questions" discussion (not e-mail). I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.

The Unity3D Game Engine

Unity is a game engine developed by Unity Technologies. Development started over a decade ago and the initial version of Unity was released in 2005. Unity has experienced rapid growth, in particular over the last few years, and is undoubtedly the most popular game engine out there. According to the Unity website, 50% of mobiles games, and 60% of AR/VR content are made with unity. The company has over 2000 employees and more than 3 billion devices worldwide are running unity [1]. There have been several major releases of Unity over the years with new minor versions being released on a regular basis. The current major release is Unity 2019 with the latest stable version being version 2019.1.10 at the time of this writing. In 2010, Unity Technologies launched the Unity Asset Store, an online marketplace where developers can obtain and sell assets for their Unity projects including tools and extensions, scripts, artwork, audio resource, etc. (Unity Asset Store [1]). Today there exists many side products and activities around the Unity platform. For instance, Unity offers its own Certification Program (Unity Certification [2]) to interested individuals and has its own VR/AR division called Unity Labs (Unity Labs [3]).

One of Unity’s main advantages is that it is cross-platform both during development time and deployment. Unity applications can be deployed for many platforms including Windows, macOS, Linux, and different mobile operating systems. That means not only can you choose on which operating system you want to create your 3D application but once it has been created, it can be deployed to a large variety of devices. For instance, you can build stand-alone programs for the common desktop PC operating systems (Windows, macOS, Linux, etc.) as well as versions for different mobile phones (e.g., Android-based phones and iPhones). Of course, the differences in performance and hardware resources between a PC and a mobile phone need to be considered, but there is support for this in Unity as well. In addition, Unity has been a front-runner when it comes to building VR applications and supports or provides extensions for a large variety of consumer-level VR devices such as the Google Cardboard, Gear VR, Oculus Rift, HTC Vive, and other mainstream HMDs. Three of the most popular VR development plugins (a series of libraries and pre-made game objects that facilitate access to HDMs and enable developers to program different functionalities) for unity are SteamVR (by Valve corporation), OVR (also known as Oculus integration, by Oculus), and VRTK (a community-based plugin by Sysdia solutions).

While its origin is in the gaming and entertainment industry, Unity is being used to develop interactive 3D software in many other application areas including:

• simulation (Universe Sandbox [4]);
• educational/training simulations (Surgical Anatomy of the liver demo [5]);
• design, architecture, and planning;
• virtual cities and tours;
• data visualization (NOAA [6]);
• history and cultural heritage;
• cognitive science research;
• and last but not least geography and GIS.

More examples can be found at Made with Unity [7]

In this course, we will use Unity to build simple interactive and non-interactive demos around the 3D environmental models we learned to create in the previous lessons. You will also learn how to produce 360° videos from these demos such that these can be watched in 3D using the Google Cardboard. Lastly, you will learn how easy it can be to add physics to different geometrical objects in unity and make them “behave” the way you want.

References

[1] Unity [8] (accessed on July 16, 2019)

Downloading and Installing Unity 

Before providing an overview of Unity’s main concepts and interface, let us start by downloading and installing Unity so that you can follow along and immediately start to experiment with the things you will learn about. Unity comes in three different versions: the “Personal” is completely free, while the “Professional” comes at a monthly fee ($125 at the time of this writing), and the “Plus” at a monthly fee (25$ at the time of this writing). For our purposes, the Personal Edition is completely sufficient. If you are interested in knowing more about the differences between the versions, an overview is provided at unity Store [9].

Please follow the instructions below to download and install the Personal Edition of Unity:

1. Go to Download Unity [10] and click on “Download Unity Hub“. The Hub is a new mechanism for managing the different versions of the Unity editor you want to install on your machine.

2. Execute the downloaded file (UnityHubSetup.exe) and go through the installation dialog. Once the installation is finished, if you have checked the “Run Unity Hub” option at the end of the installation process, when you click on Finish, the Unity Hub will open. Alternatively, you can also navigate to your desktop and double click on the newly created Unity icon named “Unity Hub” to start it.

3. You should be able to see a window as depicted below. Locate the profile icon on the top right corner of this window, click on it, and then select “Sign in”. A new window will pop up asking for your login information. Sign in with your unity account. If you do not have a unity account, go ahead and create one using the “create one” link on the pop-up window, and then sign in.

   

   Credit: Unity [11]
   

   Credit: Unity [11]

4. Once you are signed in, make sure the “Installs” category is selected on the left panel (the one highlighted with the red area in the figure below) and click on the blue “Add” button. A new window with pop up where you can select which version of unity you want to install. At the time of writing this, the latest stable version is 2019.1.10f1. Please download this version as it is compatible with the rest of the instructions given in the course (if you choose to install a new version of the editor, you might need to change some of the c# codes we will be using). To do so either click on the "Download archive" on the window that has poped up, or follow this link (https://unity3d.com/get-unity/download/archive [12]). This action will open a new tab in your default web browser. On that web page, select the Unity 2019.X, navigate to almost the end of the page and then click on the green button next to "Unity 2019.1.1" that says "Unity Hub". This will open this version of Unity editor in the Unity Hub for you to download and install. 
   This action will automatically proceed to the next dialog window in the Unity Hub, where you can select which extra modules to install. If you do not have Microsoft Visual Studio, it will be automatically selected for you on this list. Moreover, if you are developing on Linux or Mac, make sure to select the relevant “Build” module for your OS, so can deploy your virtual experience as a desktop application later. Click “Next” and wait until the installation is finished (This could be a lengthy process, so be patient).

   

   Credit: Unity [11]

5. Once the installation is complete, you should have a Unity icon (with a specific version) on your Desktop and “Unity” in your Start Menu. Before Starting Unity, we need to create a project. To do this, make sure the “Projects” category is selected in the Unity Hub (the one highlighted with the red area in the figure below) and click on the blue “New button”. Unity provides several templates for us to choose from (depending on the purpose of the project, e.g. 2D, 3D, VR lightweight RP, etc.). For the purpose of this lesson, we will use the default 3D template. Change the name of your project to “MyFirstUnityProject”. You can also change the location where the project will be saved to another address if you want (this is optional and solely based on your preference). Press “Create”, and after a few minutes the unity editor will be ready for us to use.

   

   Credit: Unity [11]

Getting More Familiar with the Editor

It is time to get more familiar with the interface and components of the Unity Project Editor and get some practical experience. The Unity web page [15] provides video tutorials on the basics and some advanced aspects of the Project Editor that we are going to rely on here. So please grab a cup of coffee, tea, or whatever you prefer, and watch the videos listed below. Please pause often to try out and practice the things explained there on the project you have. In particular, make sure to practice changing the view by panning and zooming, as well as quickly changing the perspective with the View Gizmo and manipulating objects in the Scene view. If something goes completely wrong, you can always delete all the folders and re-import the unity package and then start over.

Video: Interface Overview (2:17 min)

Video: The Scene View (4:20 min)

Video: The Game View (3:11 min)

Video: The Hierarchy and Parent-Child Relationships (3:48 min)

Video: The Project Panel and Importing (2:34 min)

Video: The Inspector (4:19 min)

Video: Build and Player Settings (1:50 min)

Video: Game Objects and Components (2:12 min)

Advanced Unity Concepts

That was quite a bit of new material but now you a very good understanding of the unity editor. We are almost done with our video tutorials before we engage in some fun practical work in the next section where we will build a very simple game! Please take a few minutes to learn about some of the more advanced features of unity using the following three videos.

Video: Prefabs (1:32 min)

Video: Tags (1:35 min)

Video: Layers (2:38 min)

Walkthrough: Using Unity to Build a Stand-Alone Windows Application

Introduction

In this walkthrough, we will use Unity to build a stand-alone Windows application from a SketchUp model. It will be a rather simple application, just featuring a keyboard-controlled camera that allows for steering the camera in a 3D scene with a single building.

Close Unity for now and download the Old Main model we are going to use here as a SketchUp .skp file. [14] You should still have the Unity project “MyFirstUnityProject” from the beginning of the lesson with just an empty scene ("SampleScene" in the scenes folder). This is what we will use for this walkthrough. The first task we have to solve is to export the 3D model from SketchUp into Unity.

Note: If the Old main model is too heavy for your personal computer, you can use the model for Walker Laboratory [16].

First Game in Unity: Roll-the-ball

The objective of this section is to get you familiar with the basics of C# programming in unity and the different awesome components (e.g. physics) offered by Unity. By the end of this section, you will be able to create a simple “Roll the ball” game as shown below:

Video: Roll the ball game (00:16) This video is not narrated.

The objective of the game is to roll a ball inside a box and collect all the available coins. The coins should simulate a rotation animation, capturing the attention of the player. Each time the ball hits a coin one point should be awarded to the player, a “cashier” sound effect played, and then that coin should disappear from the scene (i.e. collected).

The following steps will help you to first conceptualize what needs to be implemented and how it should be done, and second, guide you on how to utilize the Unity3D game engine to realize the needed game objects, mechanics, and functionalities.

1. Close your unity editor and open the Unity Hub. Create a new project (you should already know the steps from the previous sections). Name your project “Roll the ball” and make sure the template is set to “3D”.

2. Before beginning the programming of the game behaviors described above, we need to set up the play area (i.e. the box) in which we will be moving the ball. To achieve this, we will use the default empty scene that comes with every new unity project. The scene should be already open and ready. To add the floor, in the Unity editor, go to the GameObject menu on top, then 3D Object -> Plane. This will add a plane to the scene. Make sure the Position and Rotation Parameters of the Transform component in the Inspector menu (Red box in the figure below) are all set to zero:

   

   Credit: Unity [13]

   Next, we need to add some color to our plane GameObject. To do this, in the project folder structure, right click on “Assets” and go to Create -> Folder. Rename this folder to “Materials”.

   

   Credit: Unity [13]

   Now right-click on the newly created materials folder and go to Create -> Material. Rename this material to “PlaneMat”.

   

   Credit: Unity [13]

   Select the newly created “PlaneMat” and change its color from the Inspector panel on the right by clicking on the color picker next to the “Albedo”. Select a color of your liking.

   

   Credit: Unity [13]

   Drag the “PlaneMat” onto the Plane GameObject in the scene. The Plane should now have color.

   Next, we need to add four walls to the sides of the Plane so the Ball wouldn’t fall off. To do this, go to the GameObject menu on top, then 3D Object -> Cube. While the newly added Cube game object is selected set its transform parameters in the Inspector menu as depicted below:

   

   Credit: Unity [13]

   Doing so will result in a wall placed on the right side of the plane. To have the proper view of the play area when running the scene or inspecting the scene output in the “Game” tab, set the position and rotation parameters of the “Main Camera” game object as shown below:

   

   Credit: Unity [13]

   Create a new material with a color of your choice inside the materials folder and name it “WallMat”. Drag this material onto the Cube game object that acts as the wall.

   To add more meaning to our scene, rename the Plane and Cube game object to “Floor” and “Wall”, by right clicking on each and then selecting “Rename”.

   Select the “Wall” game object, hold down the Ctrl button and press D (you can also right click on the wall gameobject and click on duplicate). if done correctly your “Wall” object should be duplicated and labeled “Wall (1)”. Change the X value of the position parameter of “Wall (1)” from -5 to 5. Using this simple process, a new wall is added to the left side of the plane.

   Repeat the same procedure to add walls to the up and down sides of the planer. Simply duplicate the “Wall” object twice more and change its parameters as shown below:

   

   Credit: Unity [13]

   At this stage, we should have the play area ready as this:

   

   Credit: Unity [13]

   Video: Roll the ball 1: A Summary of what we have done so far (Step 2) (03:19) This video is not narrated.

3. Next, we need to add a ball to our scene and make it controlled by the player and roll around the play area. To add a ball to the scene, go to GameObject -> 3D Object -> Sphere. Change the name of this game object to “Ball”. Set its transform parameters as shown below. And add a material (Create “BallMat”) with a color to it.

   

   Credit: Unity [13]

   If we play ( ) the scene, you will realize that the ball will float in the air instead of dropping on the plane. The reason for this is that the ball game object does not have any physics attached to it yet. To fix this, select the ball game object, and in the Inspector panel, click on “add component”, search for “Rigidbody” and hit enter.

   

   Credit: Unity [13]

   Doing so will add a Rigidbody component to the ball game object. You may notice that the “use gravity” parameter of this component is checked by default, which will add gravity to this game object, and therefore it will drop onto the plane. Press play and see the result.

4. Rolling the ball: To enable the player to control the movement of the ball, we will use the arrow keys (the up, down, left, and right keys) on the keyboard. The idea is that by pressing the up arrow key we will make the ball roll forward, the down arrow key, backward, and the left and right arrow keys, to the sides. To achieve this, we will need to do a little bit of C# programming using the physics engine of Unity.

   Create a new folder in the project panel called “Scripts”. Right-click on this folder, select Create -> C# Script. Rename this script to “BallMovement” (Make sure you use the same exact spelling for the script name -case sensitive- if you are planning to copy the source code!). Drag this script onto the Ball game object. Double click on the script to open it in Visual Studio (this could take a while, and you might be asked to log in. You can either create an account or explore different options provided to you). Our simple ball movement script should look like this (Please read the comments in the code for further explanation). Either type or copy (make sure the name of the class i.e. “BallMovement” is spelled exactly as you have name named the script file) the following code into your script (note, the lines in green are comments are not executed by the engine, they are just extra explanation for you to understand the logic behind the code. Therefore, if you decide to type the following source code into your script, you do not need to write the lines in green):

   using System.Collections;
   using System.Collections.Generic;
   using UnityEngine;
   
   public class BallMovement : MonoBehaviour
   {
       // we need to define a variable that controls for the speed with which the ball rolls
       // the declaration of variables is done here
       // the type of the variable is float and its label Speed. The float type means that the value of Speed can be with precision points e.g. 15.5 
       public float Speed;
   
      
   
       // FixedUpdate is called several times per frame which will create the illusion of smooth movement
       void FixedUpdate()
       {
           // we need to take the input from the arrow keys pressed by the player. By default in unity, the left and right arrow keys are labeled as "Horizontal" and the up and down arrow keys as "Vertical"
           // we will define two variables where the value of each will be set "several times per frame" if the player presses the HorizontalMovement (i.e. the left or right key) and/or the VerticalMovement (i.e. the up or down key)
           float HorizontalMovement = Input.GetAxis("Horizontal");
           float VerticalMovement = Input.GetAxis("Vertical");
   
           // since we are dealing with three dimensional space, we will need to define a 3D vector based on which the ball should move. As such, we define a Vector3 called MoveBall that takes three parameters of X,Y,Z
           // movement on the X axis will be our HorizontalMovement (i.e. the left or right key) and on the Z axis the VerticalMovement (i.e. the up or down key). As we do not want to move the ball in the Y axis in the 3D space (i.e. up and down in the 3D space), the Y value will be set to 0
           Vector3 MoveBall = new Vector3(HorizontalMovement,0,VerticalMovement);
   
           //lastly, we will need to access the physics component of our ball game object (i.e. the Rigidbody) and add a force to it based on the values of the vector we just defined. We will multiple this force value with our Speed variable to be able to control the Speed of the force as we wish.
           gameObject.transform.GetComponent<Rigidbody>().AddForce(MoveBall * Speed);
       }
   }
   
   

   Once you are done populating your script with the source code above, make sure you hit save. It is absolutely important to remember that every time we modify a script, we save it so that Unity updates the editor based on the changes we have made.

   

   Credit: Unity [13]

   If we go back to unity and select the ball game object, we will see that in the inspector panel under the “Ball Movement” script, there is now a “Speed” variable that we can set. Change its value to 25 and hit play. Use the arrow keys to roll the ball inside the play area.

   Video: Roll the ball 2: A Summary of what we have learned so far (Steps 3 and 4) (02:11) This video is not narrated.

5. Adding coins to the scene: download the unity package file roll the ball assets [14]. Double click on this file, and it will open an “Import Unity Package” window inside unity. Click on import. Doing this will add two new folders in your assets hierarchy. One is called “Coin” which contains the model we will be using for the collectibles in our game. The other is called “Sounds” which will be covered in the next steps.

   Go to the “Coin” Folder and select the Coin model. Drag this model into your scene and place it somewhere inside the play area. Change its transform parameters as follows:

   

   Credit: Unity [13]

   We will now add a rotation effect to this coin to catch the attention of the player. To do this, create a new script inside the “Scripts” Folder called “CoinRotation”. Drag this script onto the coin game object. Double click on the script to open it in visual studio. Our simple coin rotation script will look like this (Please read the comments in the code for further explanation):

   using System.Collections;
   using System.Collections.Generic;
   using UnityEngine;
   
   public class CoinRotation : MonoBehaviour
   {
       // we need to define a variable that controls for the speed with which the coin rotates
       public float RotationSpeed;
   
       
       
       void FixedUpdate()
       {
           // We need to instruct this object to constantly rotate around its own Y axis (i.e. up)
           // this is done by accessing the transform component of this gameobject and using the built-in RotateAround unity function
           // this function takes three parameters. first one indicates the point in the 3D space where the rotation should happen. Since we want the coin to rotate around itself, we will pass the position of the coin itself as this parameter
           // the second parameter indicates around which axis should the game object rotate. we will set this to the up axis so the coin rotates around the Y
           // the third parameter indicates the speed with which the coin should rotate. for this we will use our RotationSpeed variable
           gameObject.transform.RotateAround(gameObject.transform.position, transform.up, RotationSpeed);
           
       }
   }
   

   If we go back to unity and select the coin game object, we will see that that in the inspector panel under the “Coin Rotation” script, there is now a “Rotation Speed” variable that we can set. Change its value to 15 and hit play. The coin should be continuously rotating around its Y-axis.

   Use the arrow keys to roll the ball inside the play area and hit the coin. You will notice that the ball will go right through the coin. The reason for this is that there is no collision happening between these two game objects. The ball game object has a Sphere collider attached to it by default, but the coin game object does not have a collider. Select the coin game object, in the Inspector panel select add component, search for “Box collider”, and hit enter.

   Play the scene and try to hit the coin with the ball again. You will notice that this time, the two objects will collide. We would need to have colliders on both objects to be able to determine when they “hit” each other. We need this to be able to collect the coins (i.e. remove the coin from the scene when the ball hits it). You may have noticed that during the collision, the coin will momentarily block the movement of the ball until it slides to either side of the coin and keeps rolling based on the force behind it. We do not want the player to experience this effect. In contrast, we want the game to be able to detect exactly when the two objects are colliding, but we do not want them to block each other in any way. The collision system of Unity can help us in achieving this goal using “Trigger”. If you select the coin game object, you will notice that under the “Box Collider” component that we just added, there is a parameter called “Is Trigger”. Enable this parameter by clicking on the CheckBox next to it. If we hit play, we can see that although we have colliders attached to both objects, the ball will not be blocked by the coin anymore.

   

   Credit: Unity [13]

6. Coin collection: create a new script called “CoinCollection” and attach it to the Coin game object. Open the script in visual studio and modify the code based on the instructions below:

   using System.Collections;
   using System.Collections.Generic;
   using UnityEngine;
   
   public class CoinCollection : MonoBehaviour
   {
    
       // this is the default unity function that will be called whenever two objects collide and one has the Trigger parameter enabled
       // the argument "other" refers to the object that hits the game object this script is attached to. 
       private void OnTriggerEnter(Collider other)
       {
           // In this case the we want to check if the "other" is the "Ball"
          // Make sure your ball gameobject is named “Ball”, otherwise you will receive an error!
           if (other.name == "Ball")
           {
               // if this condition is correct and indeed the Ball game object has hit this game object where the script is attached (i.e. the coin), we will remove this game object
               Destroy(this.gameObject);
           }
       }
   }
   

   Duplicate the coin game object several times and spread the coins across the play area. Play the scene and hit the coins. You will see that as soon as the ball hits a coin, that particular coin will be “destroyed”.

   Video: Roll the ball 3: A summary of what we have learned so far (Steps 5 and 6) (03:41) This video is not narrated.

7. Point system: Before destroying a coin upon collision with the ball, we want to reward the player with a point for managing to collect it. To implement this functionality, create an empty gameobject by going to GameObject -> “Create Empty”. Rename this empty game object to “Point System”. Create new script called “PointSystem” and attach it to the “Point System” game object. Open the script and modify the code based on the instructions below:

   using System.Collections;
   using System.Collections.Generic;
   using UnityEngine;
   
   public class PointSystem : MonoBehaviour
   {
       // we need to have a variable that holds the value of the points we aggregate
       public int Points;
   
       // we need to defined a GUIStyle profile for our graphical user interface (GUI) that shows the value of points to change its font size, shape, etc.
       public GUIStyle PointStyle;
   
       // this is the default unity graphical user interface (GUI) function. It will render GUI elements on the screen on a specific 2D coordinate 
       private void OnGUI()
       {
           // a GUI label to show the value of the aggregated points, place at the X=10, Y=10 coordinates, with width and height of 100, the next argument is the content that the label shows which is in this case
           // a numerical value. we need to convert the numerical value to a string (text) to be able to show it on the label. The last argument indicates which GUIStyle profile should be used for this label
           GUI.Label(new Rect(10,10,100,100),Points.ToString(),PointStyle);
       }
   }
   

   The script described above is responsible for holding the value of the points the player aggregates and visualizing it on the screen. To increase the points however, we will add a line to the script responsible for detecting when the ball hits a coin. For this go back to the “CoinCollection” script and modify it based on the instructions below:

   using System.Collections;
   using System.Collections.Generic;
   using UnityEngine;
   
   public class CoinCollection : MonoBehaviour
   {
        // this is the default unity function that will called whenever two objects collide and one has the Trigger parameter enabled
       // the argument "other" refers to the object that hits the game object this script is attached to. 
       private void OnTriggerEnter(Collider other)
       {
           // In this case the we want to check if the "other" is the "Ball"
           if (other.name == "Ball")
           {
               //if this condition is correct and indeed the Ball game object has hit us, access the Point System game object, then the PointSystem script attached to it, and increase the Points variable by 1
               GameObject.Find("Point System").GetComponent<PointSystem>().Points += 1;
   
               // we will remove this game object where the script is attached to (i.e. the coin)
               Destroy(this.gameObject);
           } }
   }
   

   Next, select the “Point System” game object. On the inspector panel on the right, in the “PointSystem” Script attached to it expand the “Point Style” GUIStyle and change it as instructed below:

   

   Credit: Unity [13]

   Press play and start aggregating points!

8. Collection sound: another feature we need to add to our game is a sound effect. We want to play a “cashier” sound effect each time the ball hits a coin. To achieve this. Create a new empty game object and rename to “Sound Management”. Select this newly created game object and click on “Add Component”, search for “Audio Source” and hit enter.

   Navigate to the “Sounds” folder in your project hierarchy and drag the “CashierSound” clip to the “AudioClip” field in the “AudioSource” component we just added to our audio management game object. Uncheck the “Play On Awake” parameter of the “AudioSource” component so the sound clip does not play as soon as we start the scene.

   

   Credit: Unity [13]

   Next, we need to instruct the game to play the audio clip whenever we collect a coin. To achieve this, modify the “CoinCollection” script based on the instructions below:

   using System.Collections;
   using System.Collections.Generic;
   using UnityEngine;
   
   public class CoinCollection : MonoBehaviour
   {
    
       // this is the default unity function that will called whenever two objects collide and one has the Trigger parameter enabled
       // the argument "other" refers to the object that hits the game object this script is attached to. 
       private void OnTriggerEnter(Collider other)
       {
           // In this case the we want to check if the "other" is the "Ball"
           if (other.name == "Ball")
           {
                //if this condition is correct and indeed the Ball game object has hit us, access the Point System game object, then the PointSystem script attached to it, and increase the Points variable by 1            
   GameObject.Find("Point System").GetComponent<PointSystem>().Points += 1;
   
               // access the audio management game object, then the AudioSource component, and play
               GameObject.Find("Sound Management").GetComponent<AudioSource>().Play();
   
               // we will remove this game object where the script is attached to (i.e. the coin)
               Destroy(this.gameObject);
           }
       }
   }
   

   Video: Roll the ball 4: A summary of what we have learned so far (steps 7 and 8) (03:13)

   Hit play and enjoy your creation!

Tasks and Deliverables

Assignment

The homework assignment for this lesson is to report on what you have done in this lecture. The assignment has two tasks and deliverables with different submission deadlines, all in week 8, as detailed below. Successful delivery of the two tasks is sufficient to earn the full mark on this assignment. However, for efforts that go "above & beyond" by improving the roll-the-ball game, e.g. create a more complex play area -like a maze- instead of the box, and/or make the main camera follow the movement of the ball, you could be awarded one point if you fall short on any of the other criteria.

To help with the last suggested extra functionality, use the following script and attach it to the main camera:

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

public class FollowBall : MonoBehaviour
{
    // reference to the ball game object
    public GameObject Ball;

    // a vector3 to hold the distance between the camera and the ball
    public Vector3 Distance;

    // Start is called once before the first frame update
    void Start()
    {
        // assign the ball game object
        Ball = GameObject.Find("Ball");

        //calculate the distance between the camera and the ball at the beginning of the game
        Distance = gameObject.transform.position - Ball.transform.position;
    }
    // This called after the Update finishes
    void LateUpdate()
    {
        // after each frame set the camera position, to the position of the ball plus the original distance between the camera and the ball 
// replace the ??? with your solution
        gameObject.transform.position = ???;
    }
}

Task 1: Find and Review Unity 3D/VR Application

Search the web for a 3D (or VR) application/project that has been built with the help of Unity. The only restriction is that it is not one of the projects linked in the list above and not a computer game. Then write a 1-page review describing the application/project itself and what you could figure out how Unity has been used in the project. Reflect on the reasons why the developers have chosen Unity for their project. Make sure you include a link to the project's web page in your report.

Deliverable 1: Submit your review report to the appropriate Lesson 7 Assignment.

Grading Rubric Unit 3D/VR Application Review

Grading Rubric

Criteria	Full Credit	Half Credit	No Credit	Possible Points
URL is provided, the application/project uses Unity, is not already listed on this page, and is not a game.	2 pts	1 pts	0 pts	2 pts
The report clearly describes the purpose of the application/project and the application itself.	3 pts	1.5 pts	0 pts	3 pts
The report contains thoughtful reflections on the reasons why Unity has been chosen by the developers.	3 pts	1.5 pts	0 pt	3 pts
The report is of the correct length, grammatically correct, typo-free, and cited where necessary.	2 pts	1 pts	0 pts	2 pt
				Total Points: 10

Task 2: Build a Simple “Roll-the-ball” Game

If you follow the detailed instructions provided in this lecture, you should be able to have a fully working roll-the-ball game.

Deliverable 2: Create a unity package of your game and submit it to the appropriate Lesson 7 Assignment.

You can do this by simply going to the Assets in the top menu and then selecting “Export Package”.

Credit: Unity [13]

Make sure all the folders and files of your project are checked and included in the package you export (you can test this and import your package in a new Unity project to see if it runs).

Credit: Unity [13]

If you choose to implement the functionality of the main camera to follow the ball movement, please explain your solution as a comment in your script. You can add comments (texts in green) in C# by using “//”.

Helpful advice:

We highly recommend that, while working on the different tasks for this assignment, you frequently create backup copies of your Unity project folder so that you can go back to a previous version of your project if something should go wrong.

Grading Rubric for Roll-the-Ball game

Grading Rubric

Criteria	Full Credit	Half Credit	No Credit	Possible Points
Your game runs smoothly and as intended without any errors or strange behavior	6 pts	3 pts	0 pt	6 pts
Your project is complete and has all the required functionalities (coin rotation, collection, and sound effect).	3 pts	1.5 pts	0 pt	3 pts
Your Unity package has a proper folder structure, and all the files have meaningful names like it was done in the instructions	1 pt	.5 pts	0 pts	1 pt
				Total Points: 10

Summary and Tasks Reminder

In this lesson, you learned about the Unity3D game engine and the role it can play in creating 3D and VR applications. You should now be familiar with the interface of the Unity editor and the main concepts of Unity and be able to create simple projects and scenes. In the next lesson, we will explore other features of Unity for building 3D applications, including adding an avatar to a scene, creating a camera animation, importing resources from the Unity Asset Store, and creating a 360° movie that can be uploaded to YouTube and be watched in 3D on a mobile phone via the Google Cardboard.

Reminder - Complete all of the Lesson 7 tasks!

You have reached the end of Lesson 7! Double-check the to-do list on the Lesson 7 Overview page to make sure you have completed all of the activities listed there before you begin Lesson 8.