UNITY | PROJECT | SPACE SHOOTER 2D | 5. Enemy Bullet & Enemy Shooting

Adding “EnemyBullet” Sprite to the scene to configure

Creating & Adding “EnemyBullet” Script

“EnemyBullet” Script

• Create Variables for “speed”, “direction”, “flag”
• Create a Function to set the Bullet’s Direction, “SetTheDirection(Vector2 direction)”
  • Be careful not to be confused with the names of variable “direction”
    • to differentiate them, put “this.” in front of “direction”(not the argument)
  • normalize the vector to get purely a direction (to make the computing correct and simple)
  • set the flag(the boolean variable) as “True” to activate the codes in “Update()” method
• In “Update()” method
  • the codes will be activated when the flag is set to “True”
  • the position of the bullet is updated every frame by calculating “transform.position” with “direction(Vector2, the result from “SetDirection()”)’
  • if a bullet goes out of the screen, Destroy it
• In “Awake()”
  • every code in “Awake()” is activated before the game starts
  • before the game starts, set “speed” and “ready” with default values

 

Creating “EnemyBullet” Prefab

 

Add “Enemy” Prefab temporally to configure

 

Adding “EnemyGun” to “Enemy” by creating Empty GameObject | Adding “EnemyGun” Script

 

“EnemyGun” Script

• Add a public GameObject variable to use EnemyBullet prefab as a component
• Create a Function to fire bullets from Enemy, “FireEnemyBullet()”
  • get a reference of “Player” by using “GameObject.Find()”
  • the way of detecting a GameObject, “if(gameObject != null)”
  • if “Player” is detected, a bullet is instantiated and its initial position is set
  • how to calculate an aiming direction: Vector – Vector
  • to use “SetDirection()” method of “EnemyBullet” Class, use “GetComponent()” towards “bullet”
• In “Start()” method
  • make “FireEnemyBullet()” activated after 1 second, by using “Invoke()”

 

Don’t forget to add the reference in the Inspector

 

Applying Changes to Prefab

• To apply changes on the prefab, Don’t forget to push “Apply” button in the Inspector

 

Enemies Spawning, Moving, and Shooting

UNITY | PROJECT | SPACE SHOOTER 2D | 4. Enemy Animation & Enemy Spawner

Creating Enemy Animation

• by selecting multiple Sprites and adding them in the scene, Create “EnemyAnimation”

 

Changing the name of EnemyAnimationController

 

“Enemy” GameObject

 

“Enemy” GameObject with Animation

 

Adding “EnemyControl” Script to “Enemy” GameObject

 

“EnemyControl” Script

• Set the speed of Enemy with a float variable “speed”
• in “Update()” method
  • change the position of “enemy” GameObject with “transform.position” every frame
  • for memory usage, destroy “enemy” when it goes out of the screen

 

“Enemy” Moving

 

“Enemy” Destroyed when outside of the screen

 

Creating “Enemy” Prefab

 

Creating “EnemySpawner” & Adding “EnemySpawner” Script

• Create Empty GameObject and change its name into “EnemySpawner”
• Create “EnemySpawner” Script and add it to “EnemySpawner”

 

“EnemySpawner” Script

• To use “Enemy Prefab” in the script as a component
  • add “Public GameObject” variable
  • Don’t forget to add the reference in the inspector
• Create a custom Function, SpawnEnemy()
  • Instantiate()
  • after instantiating, set the position of Enemy in a random position by using random range of “x” value
• To make it spawn in 5 seconds
  • in “Start()”, write “Invoke(string methodName, float time)”
  • set the “maxSpawnRateInSeconds” as 5 seconds

 

Enemy Spawning

 

Don’t forget to add the reference

 

“EnemySpawner” Script

• Create a function, “ScheduleNextEnemySpawn()” to spawn multiple times
  • by using, “Invoke()” and putting “ScheduleNextEnemySpawn()” inside “SpawnEnemy()”
    • without using “loop”, we can make enemy spawned continuously
• To increase the difficulty of the game, Create a function, “IncreaseSpawnRate()”
  • in “Start()”
    • by using “InvokeRepeating(sting methodName, float time, float repeatRate)”
      • every 30 mins, the Spawnrate will be increased(Spawning gets faster)
      • In “InvokeRepeating()”, “time” is 0 and “repeatRate” is 30, meaning every 30 secs, “IncreaseSpawnRate()” is invoked

 

Spawning Enemies