Game Development Session - 3 | Introduction to Unity

The KODERUNNERS Community
• Unity Scripting 101
Introduction to Scripting in Unity using C#
By : Soumik Rakshit

Be Sure to Match the instructions with the
screenshot on the next page.
 If you have set up a project in Unity, you will get an interface which looks something like this
irrespective of the version you are using.
 In the hierarchy panel, there are 2 game objects by default - Main Camea and Directional Light.
 If you click on any game object, their properties are shown on the isnspector panel.
 The game as seen from the eyes of the main camera is displayed in the game view panel.
 Other than these we also have the Project and Console Panel.
Game Development 101 - Soumik Rakshit

Creative Coding 101 - Abhik Biswas

Our Objective
 Our objective is to create a console based game which helps us to digest the concepts of Unity C#.
 We won't be using any kind of Graphics for the current game.
 The game primarily shows the player a random time limt between 5 and 21 seconds and starts
countdown to that time.
 The game asks us to hit space when we think we are close to that time.
 Finally it shows the player how accurate he/she was to guess the correct time.

Starting with the Game.....
 First of all you need to create an empty game object.
 Press ctrl+shift+n to create an empty gameObject.
 You will see that the empty gameObject has been created.
 The purpose of the empty gameObject is to hold the script that we are writing.

Remember
 The concept of Unity is just like shooting a movie.
 In a movie the director directs the actors according to the scripts written by the scriptwriter in front
of the camera.
 In Unity the gamObjects(instead of actual actors) behave according to the scripts you write(that
makes you the scriptwriter and Unity itself the director) in front of a camera.
 The empty gameObject will behave according to the script we attach to it.
 We are not involving any camerawork this time, so our game will be played on the Unity Console
Panel.

Starting off the script
 First in your project panel, open the Assets folder.
 We will be creating our script inside the Assets folder.
 Right click , then select Create and finally select C# script. Name the empty script TimeGame(or
any other fancy name you like).

Adding the Script to the GameObject
 When you select the empty GameObject, you can see its properties on the Inspector Panel
 Under its properties, there is a button called Add Component.
 Go to Add Component, then Scripts, then TimeGame(or whatever name you have given to the
script).

Opening the Script
 Double Click on The script to open it.
 Now the script opens using the default code editor which is there with your version. If you are using
Unity 5.6, then most probably it is Visual Studio.
 For the tutorials I have used MonoDevelop. If you have any issues regarding the code editor
please let me know.
 The default code looks something like the one showed in the next screenshot.

Similar to Processing
 The code structure of Unity C# is exactly similar to p5.js or Processing Java or Processing.py
 The function void Start() is called initially at the beginning of the game. Hence it can be used for
setting up the initial conditions and initialization of variables and objects.
 The function void Update() is called once per frame.
 Note: By default frame rate might be 24 or 30 fps depending on the version of Unity. It means that
the Update function is called 24-30 times per secon depending on the version.

The print() function
 To print anything on the console, we use the print() function.
 At first we use it to print out the initial message.
 We ask the player to hit the spacebar when he thinks it is the time.
 Save the script and run it.
 Note: In order to run the game, use the play, pause and stop buttons. To run the game, hit the play
button and to stop the game, hit the play button again.
 Note: You cannot run a single script in a game. When you hit the play button, you run the game as
a whole. It is not an issue at present since we will be dealing with a single script.

Setting the Random Time
 For setting the random time we create a function void setRandomTime().
 For setting the random time, we use the Range function under the Random class.
 The Range function takes two parameters - lower range(inclusive) and upper range(exclusive).
Hence to generate a random value from 5 to 20, we write the following code: waitTime =
Random.Range (5, 21);
 Note: Be sure to declare waitTime globally as an integer variable. Just write in the global scope: int
waitTime;
 Note: Any uninitialized global variable is automatically initialized to zero.

Setting the Start Time
 We set the start time as the current time.
 This can be done with the member variable time which is a member of the Time class. Time.time
stores the current clock time in seconds.
 We just store Time.time in a variable roundStartTime in the Start() function and then print it out.
 Note: Be sure to declare roundStartTime globally as a float variable.
 Note: We should also call the setRandomTime() function in the Start() function. You can also print
the waitTime value within the setRandomTime() method.
 Note: If you run the code at this point, you might get a warning message that you have not used
the roundStartTime variable. Ignore it and run the code.

Summing up Initialization
 This far we have set the initial conditions.
 We have set the player wait time (waitTime) to a random value in the range 5-20.
 We have set the start time (roundStartTime) to the current clock time before calling the update
function.
 PS: You can print and check out the value of the roundStartTime variable, but we do not need to do
so in the actual game.

Checking keyboard input
 In the Update() function we check whether the the player has hit the spacebar or not.
 To do so we check the value returned by GetKeyDown() which is a boolean type member method
of the Input class. It checks whether a certain key has been pressed down or not.
 The required value should be KeyCode.Space.
 Hence we write the following code: if (Input.GetKeyDown (KeyCode.Space)){ }

Creating the mechanics
 Now we move on to the actual game mechanncs. Game mechanncs is that part of the code which
contains the functional aspects of the code.
 Inside the if block(i.e, when the player has hit the spacebar). We can get the time the player has
waited to before hitting the spacebar.
 We can do this by the subtracting the roundStartTime from the current time. The following code can
be used: float playerWaitTime= Time.time-roundStartTime;

Showing the Time lag
 We will be diplaying how much difference is there between the playerWaitTime and waitTime.
 To do so we write the following code: float error=Mathf.Abs(waitTime-playerWaitTime);
 Now we just print out the result using the print().
 Note: Mathf.abs returns the absolute value of a float value.
 Note: We need the absolute value becouse the player might hit the spacebar after the alotted time.

Assignment
 That sums up the basic game mechanics.
 Now you could print out different messages to the player based on the error.
 In doing so you can use if-else or switch case.

HAPPY CODING & HAPPY GAMING

Game Development Session - 3 | Introduction to Unity

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