MiniGame2: Pizza Carnage
************************

This game consists of eliminating waves of aliens by throwing pieces of pizza at them.

You will learn to:

	* Create a spawner
	* Use randomness
	* Create and use Prefabs
	* Detect collisions
	* Model a pizza and an alien with their colliders
	 

 


Scene Layout
============

	* Open the Assets folder named *MiniGames*
	* Inside this folder, create a new Scene named: *Pizza Carnage*
	* Create a ground of 10mx10m, apply a green color
	* Create a capsule to represent the player
	* Create 3 objects to represent the aliens
	
	.. image:: farm.png
		:scale:  30%
		
Player control
==============

	* Create a controller script for the player:
	
		* Player can move left and right using the arrow keys
		* Add a test to prevent the player from going off the ground
	
	.. image:: farmermove.gif
		:scale: 50%
	
Pizza
=====

Without a doubt, the most interesting part of this project is coming up: modeling a slice of pizza in 3D

 	
	.. image:: pizza.png
		:scale: 50%

	* Add a script to make the pizza move at a speed of 10m/s in the direction of the aliens
	
	.. image:: fly.gif
		:scale: 50%
		
Prefab
======

The player will throw pizza slices to the aliens, so we need to reuse the same slice of pizza multiple times.
For this, we transform our 3D pizza slice into a prefab.

	* Drag an drop your pizza slice into the *MiniGames* folder
	
	.. image:: pizzaprefab.png
		:scale: 50%
	
	
	* Delete the pizza from the scene
	
	* Enter Play mode
	
	* Drag and drop the pizza slice into the hierarchy window, this will instantiate the pizza prefab in real time
	
	.. image:: pizzattack.gif
		:scale: 70%
	
	
	* Exit Play mode
	
	
Firing pizza
============

	* Go back in the player controller script
		
		* Add a new variable: *public GameObject pizzaSlice*

	* Link this variable to your prefab
	
	.. image:: link.gif
		:scale: 80%
		
	* In the *update()* function, detect when the spacebar is pressed
	
		.. code-block:: csharp
			
			if ( Input.GetKeyDown(KeyCode.Space) ) 
			
	* If we look at the documentation:
	
		.. image:: docinstantiate.png
			:scale: 80%
	
	* We notice a version that is interesting:
	
		* First parameter: the prefab we want to instantiate
		* Its position
		* Its rotation
		
	* Instantiate a prefab when spacebar is pressed
		
		* At the player position
		* Using the rotation transform of the prefab

		.. image:: firingseq.gif
			:scale: 50%
	
Self-destruction
================

In order to improve game performance, we need to destroy projectiles when they go out of bounds.

	* When a pizza slice if far away (> 10m)
	
		* Destroy the current object using:
		
	
		.. code-block:: csharp
		
			Destroy(gameObject); 
	
		.. image:: fardestroy.gif
			:scale: 60%
			

Alien Spawner
=============

	* Transform you three aliens into prefab
	
	.. image:: newprefab.png
		:scale: 40%
	
	* Delete aliens from the scene
	
Our spawn manager script will be associated to a hidden GameObject:

	* Right click in the *Hierarchy windows* and select: *Create Empty*
	
	* Rename this object to *spawnmanager*
		
	* Create a script and attach it to the spawn manager
	
	* Edit the script and add an array of prefabs as a public member:
	
		
		.. code-block:: csharp	
		
			public GameObject[] alienPrefabs; 
	
	* Select the spawnmanager object
	
	* In the Inspector window, set the size of the array to 3
	
	* Drag and drop the 3 alien prefabs to fill the array
	
	
	.. Warning: We remind you that a **Vector3 is a C# structure**, which means that when you write: *Vector3 V2 = V1*, V2 is an independant copy of V1.
	

	* Create a function *Spawn()* in the *Spawnmanager* script
		
		* Randomly choose the alien prefabs

			.. code-block:: csharp	
			
				int randomValue = Random.Range(0, 3);  // generate a random integer number between 0 and 2
		
		* Make the alien appears in front of the player by randomly choosing  its location
		
		* Call the *Spawn()* function from the *Start()* function
		
		.. dropdown:: Help in case nothing works
			:animate: fade-in

	 		.. code-block:: csharp
			
				void RandomSpawn()
				{
					int r = Random.Range(0, 3);

					Vector3 V = alienPrefabs[r].transform.position;
					V.z = Random.Range(-6, 6);
					Instantiate(alienPrefabs[r], V, alienPrefabs[r].transform.rotation);
				}

	* Enter Play mode:

	.. image:: R1.png
		:scale: 70%
		
	* Remove the *Spawn()* function from the *Start()* function
	
	* We now spawn the aliens on a timer
	
	
	
	
		.. code-block:: csharp
		
			void Start()
			{
				float startDelay = 2;
				float spawnInterval = 3;
				InvokeRepeating("RandomSpawn",	startDelay, spawnInterval);		
			}

		
		
		
		
Collision
=========

	* Double click on the pizza prefab
	
		* Add a box collider component
		
			* Click on Edit collider

			* Select scale Tool and reduce the collider to fit the shape of the pizza
		
			.. image:: editbox.png
				:scale: 40%
	
			
	* Go back to the scene
	
	* Create a new script for aliens and associate this script to each alien prefabs
	
	* This script must destroy the alien and also the pizza
	
	
		.. code-block:: csharp
	
			 Destroy(gameObject);
			 Destroy(other.gameObject);
	
	* **Configure the collision system so that the game works properly**
		
		* Configure colliders if needed
		* Select the right function for collision management
		


Here is the final version of the game:

	.. image:: kill.gif