Develop Reference

Leveling in Unity

I'm new at programming and don't know how to make a level counter that can be accessed in every scene.
I created a 3D game. When the player has completed level 1, then I want level 2 to be unlocked using this method:
When the player has completed the level, the value of the level counter changes to 2 and the trigger can access that level counter.
The below is not my code, but is just there to make it more clear:
var level = "level counter which is 2 in this case"
if level == 3
active the trigger (trigger teleports the player to level 3)
else {
floatMessage("You haven't finished level (?) yet.")
}

Looks like you need a persistance system.
There are many ways to save your game state. The easiest and most accessible remains the PlayerPrefs, although it is not optimal for more complex saves.
You could save your amount of levels unlocked (assuming it is incremental) by using this call :
PlayerPrefs.SetInt("levelsUnlocked", 3);
and then you can retrieve the value by using :
levelsUnlocked = PlayerPrefs.GetInt("levelsUnlocked", 0);
Note : The second parameter here is a default value assigned in case you haven't saved before.
Hope it helps. If you're looking to upgrade your save game, consider writing your own save file class and serialize it using JSON. https://docs.unity3d.com/Manual/JSONSerialization.html
The former option remains convenient for a simple project.

There's a few ways to handle this. My recommendation is to store game progress data to a file or database outside the scope of the scene (a good file-based DB solution is SQLite - here's a wiki post I made on how I implemented SQLite in one of my recent projects).
However, if you only wish game progress to persist during the life of the game (it always starts at level 1 when you start it), then Singletons and DontDestroyOnLoad are also a good solution, as #BugFinder mentioned.
public class LevelManager : MonoBehaviour
{
private static LevelManager instance;
public static LevelManager Instance { get => instance; }
int levelNum = 1;
public int LevelNum { get => levelNum; }
private void Awake()
{
//Check to see if an instance of the LevelManager already exists.
if(instance != null && instance != this)
{
Destroy(this.gameObject);
return;
}
instance = this;
DontDestroyOnLoad(this.gameobject);
}
public void LevelComplete()
{
levelNum++;
}
}
As long as the above code is attached to a gameobject in your scene, you can call the following from another gameobject's script. You will notice that I encapsulate levelNum and instance. This is to enforce good practice in my other code. I know that the only script that can modify levelNum or instance is LevelManager, so I won't accidentally break something by changing one of those values in another script accidentally.
Be careful to only put the above script on a gameobject that is allowed to persist between scenes. I like to create an empty "Singletons" gameobject that just holds my singletons.
Example usage when defeating the final boss (if that's a way to beat your levels):
void BossDefeated()
{
LevelManager.Instance.LevelComplete();
}
Example usage when checking to see if a portal can be opened:
int portalNum = 3;
bool CheckPortal()
{
if(LevelManager.Instance.LevelNum >= portalNum)
return true;
return false;
}

Could you just use a Static int if you just want something quick:
public static int level;
Then from anywhere, call the class name i.e. LevelManager.level;
If you want to have it trigger something, you are better off having a callback of some sort, and making it private with a public get, which in turn calls something like a UnityEvent. This answer will probably not be very popular, but it is quick to do :)

Can I define a (random) variable in the beginning of a C# program, that stays the same for the whole program?

I'm trying to make a text-based dungeon explorer in C#, and I have the maze-part all working. I used some methods that refer to each other when you pick a direction you want to go in.
The "map" is divided in 13 rooms total. This is an example for when you leave the starting room .
Console.WriteLine("REMEMBER! You are always looking north when deciding which room you go in.");
Console.WriteLine("one room goes right in front of you, one goes behind you, another one goes to the right and the third one goes straight in front of you.");
Console.WriteLine("if you want to give up, type 'give up'");
Console.WriteLine("which way do you go?");
choice = Console.ReadLine().ToLower();
while (choice != "behind" && choice != "right" && choice != "in front" && choice != "give up")
{
Console.WriteLine("you cant stay here, can you?");
Console.WriteLine("Type: 'behind', 'right' of 'in front' to move in a specific direction.");
choice = Console.ReadLine().ToLower();
}
switch (choice)
{
case "in front":
Console.Clear();
room1();
break;
case "behind":
Console.Clear();
room11();
break;
case "right":
Console.Clear();
room7();
break;
}
And this is the maze itself:
Just a maze is fun, but I would like there to be an element of surprise. I was thinking of putting a monster in room 8, for example. The monster doesn't have to be there every game. At the beginning of the game, I would like to define a variable that decides if there is going to be a monster or not (I was planning on doing this with an array and a random number so it would be 50/50 chance). The problem is to keep the variable, so it doesn't change every time you move to a different room.
Does anyone know how I can define a variable (or maybe something else that I don't know? I'm somewhat new to programming in multiple methods) at the beginning of the game to determine if there is a monster or not? I have tried working with various classes, but I have never done this before, so I don't know how I can work in different classes in de same namespace.
I will also further use this to determine in what room the sword to slay the monster is in and in what room the key to the escape door is etc.

I am not quite sure I understand what you want to achieve, but a simple answer could be to have a Room class, which itself determines if it has a monster. This can be randomized in the objects constructor (the method which is called, when a new instance of the object is initialized).
As mentioned by Olivier though, you cannot have the actual random number generator in the class itself, so I have placed that in a utility class...
Something like this:
public static class Utility
{
private static readonly Random random = new Random();
// Returns true or false, with a user defined chance of 'True'
// E.g. chanceForTrue = 30 means a 30% chance of 'True'
public static bool GetRandomBool(int chanceForTrue)
{
return random.Next(101) < chanceForTrue;
}
}
public class Room
{
// If true, there is a monster in the room
private readonly bool hasMonster;
// Constructor
public Room()
{
// 50% chance of having a monster
hasMonster = Utility.GetRandomBool(50);
}
// ...rest of the class
}
The method Random.Next(2) will return an integer less than 2 (so 0 or 1), meaning there is a 50/50 chance of the room containing a monster. You can adjust this to whatever you like.
You simple get a room by saying:
var room8 = new Room();
However, this is generally not a good way of storing multiple instances of the same object (class). You should look into storing them in a collection of some sort, maybe a dictionary:
var rooms = new Dictionary<int, Room>();
rooms.Add(8, new Room()); // Adds a room with key '8'
And the logic of which rooms are adjecant, could be stored in a map or in the Room class itself, by having a list of AdjecantRooms. But now we are kinda getting away from the orignal question, so I will stop myself :-).

A solution would be to have code run through those variables and react accordingly (spawn the monster in the specified room, or not at all) before the game starts.
You could put these variables in your dungeon generator class either as is, or wrapped inside a struct for easy-reading. As your dungeon-generator class would persist throughout the whole game, you should have no problem with keeping the variable the same when moving through rooms.
If this solution is inappropriate or inaccurate for your situation, please provide more details in your current implementation so we can give more correct advice.

Passing a class that use a method as a member

I've been learning C# for the past 6 months or so and am currently stuck on a turn-based battle system for a game.
I have tried a couple of different things and watched loads of videos about it but I didn't find what I was looking for. Maybe it's impossible but here it is. Also, I'm not looking for someone to write the code or anything, I am mainly looking for pointers.
switch (currentBattleState)
{
case (BattleState.WAIT):
{
if (heroesToManage.Count > 0)
currentBattleState = BattleState.ACTION_SELECT;
break;
}
case (BattleState.ACTION_SELECT):
{
foreach(Button button in buttons)
button.interactable = true;
break;
}
}
This is the current status of the battle state machine. I have two buttons at the moment, one that will attack and one that will open a spellbook to choose which spell to cast.
What I would need is something like this pseudocode:
void OnClicked()
{
ChooseSpell(); // If it's the "magic" button
ChooseTarget();
// And this Action will pass the target to the Attack() or Cast()
// function on the HeroStateMachine
listOfActions.Add(new Action(origin, target, Attack() or Cast())
}
and then when each Action is processed by the BattleStateMachine, like so, again in pseudocode because I have no idea how to do it:
void ProcessAction(Function action, int index = 0)
{
// This would result in Cast(origin, target) or Attack(origin, target)
action(listOfAction[index].origin, listOfAction[index].target);
}
// And then call it like this ?
ProcessAction(listOfActions[0].function)
we remove it from the list so, basically, this would be a first-in first-out type of thing.
The issue is that I haven't found a way to do that. So far, the videos I've watched are creating a derived class for every single type of attack, spell or item (all derived from a BaseAction)... Which I don't want to do since this seems like really wet code... Also, I wouldn't want to create a whole new class every time I want to add something to the game...
As I said, I'm not looking for full code but so far you've all been helpful so maybe just a pointer to what I could use to do what I want? Or just tell me if I'm approaching this whole thing from the wrong angle.

Class to control two classes in Unity

I have almost identical classes, PaddleLeft and PaddleRight. I am tired of calling both of those classes when I need something done, I rather them be done all at once. For example, here is what I have to do:
public void pause() {
GameObject.Find("Paddle Objects/paddleRight").GetComponent<Paddle>().setIsPaused(true);
GameObject.Find("Paddle Objects/paddleLeft").GetComponent<Paddle>().setIsPaused(true);
}
And here is what I want to do:
public void pause() {
GameObject.Find("Paddle Objects/paddles").GetComponent<Paddle>().setIsPaused(true);
}
This seems unnecessary, however, in my game, there are times where the same line of code are copied and adjusted to up to ten similar objects.
Question Is there a way to make a super class like in Java for these objects. I have searched the internet and have found info, however I can't seem to understand how to make it work because I can't extend MonoBehavior and a superclass in Unity.
Thanks in advanced!

I have almost identical classes, PaddleLeft and PaddleRight
But your code is totally saying different stuff
GameObject.Find("Paddle Objects/paddleRight").GetComponent<Paddle>().setIsPaused(true);
GameObject.Find("Paddle Objects/paddleLeft").GetComponent<Paddle>().setIsPaused(true);
Maybe you want meant to write the code below?
GameObject.Find("Paddle Objects/paddleRight").GetComponent<PaddleRight>().setIsPaused(true);
GameObject.Find("Paddle Objects/paddleLeft").GetComponent<PaddleLeft>().setIsPaused(true);
I will assume the second code is what you meant to write.
When you have multiple GameObjects or Scripts with similar actions, you should create a central manager script that will make it easy to communicate with a those GameObjects or classes.
Since both your classes are called PaddleRight and PaddleLeft, You can simply call this class PaddleManager.
Don't forget that, of course, PaddleManager is just a script, it's not a "thing" in Unity. Naturally you will attach PaddleManager to some game object. You might ask "where should I attach it?" In a simple game, you might attach it to your camera, say. (Since you always have a camera, other developers working on your project always know to "look n the camera" for odds and ends like sound-effects, managers like this and so on.) Alternately, say that physically all your paddles are associated with (for example) an object that is the ping pong table. Then, a good place to attach PaddleManager.cs would be on the ping pong table. It doesn't matter where you attach it, so long as it is tidy. Some people like to make simply an empty object (you can refer to an empty object as a "marker"), just make an empty object named say "manager holder", put it at 0,0,0, and you can add scripts like PaddleManager.cs to that object.
Your PaddleManager.cs script:
public class PaddleManager : MonoBehaviour
{
private PaddleRight rightPaddle = null;
private PaddleLeft leftPaddle = null;
//Initialize variables
void Start()
{
//Get reference/Cache
rightPaddle = GameObject.Find("Paddle Objects/paddleRight").GetComponent<PaddleRight>();
//Get reference/Cache
leftPaddle = GameObject.Find("Paddle Objects/paddleLeft").GetComponent<PaddleLeft>();
}
//Call to pause and unpause
public void pause(bool pausePaddle)
{
rightPaddle.setIsPaused(pausePaddle);
leftPaddle.setIsPaused(pausePaddle);
}
}
Now, you can access both of your Paddles from one script, in another script.
public class YourOtherScript : MonoBehaviour{
PaddleManager paddleManager = null;
void Start()
{
//Get reference/Cache
paddleManager = GameObject.Find("GameObjectPaddleManaerIsAttchedTo") .GetComponent<PaddleManager>();
//To pause
paddleManager.pause(true);
//To un-pause
paddleManager.pause(false);
}
}
By doing this, you will avoid using static variable and also avoid using GameObject.FindGameObjectsWithTag("paddles")) in foreach loop like mentioned in the other answer. GameObject.Find... functions should NOT be used in the middle of the game because it will slow down your game. You need to use it once and cache the GameObject in the Start function, then you can re-use it without slowing down your game.

First of all paddle right and left are game-objects and not classes , the class name is paddle , and if the same script is on both the objects , the most simplest way would be to put it on another empty object and call it once and the code will work on all game-objects that the script is attached to . BUT! that is only regarding to what I cuold make out of your question , Here is what I really recommend , as you said "because I can't extend Mono-behavior and a super-class in Unity" . Ok so you have class A inheriting monobehavior , and you make class's B and C, then when you inherit them from A you will get all the abilities of a monobehaviour in class B and C and you can attach them to game objects , you can even make start and update functions as vrtual and override them in B and C and you can even call A's function use the keyword Base , So read on it , it will take time but in the long run makes you a better coder

Mm, wait. There is something wrong with your question:
YouPaddleLeft and PaddleRight are not classes. They are GameObjects existing in Unity scene. Class is Paddle to which you get reference by GetComponent<Paddle>() .
Now if you have a variable/function that affects all the instances of the class the same than you shell make them static. (Google static variables and functions if you don't know what they are).
So go to your Puddle class and change the declaration of setIsPaused(bool val) to this:
public static void setIsPaused(bool val) { /* implemenetation */ }
and then make a call to it via class token, not object:
Paddle.setIsPaused(true/false);
note that if the static function has references to class variables all those variables should be marked static as well. (e.g. if you have a bool isPaused than mark it static because it should be the same for all the objects all the time anyways)

How to avoid casting from interface to class

In trying to design a collision detection component for a game, I came up with the following solution. I define an interface ICollideable that looks something like:
interface ICollideable
{
Sprite Sprite { get; }
int Damage { get; }
void HandleCollision(ICollideable collidedWith);
}
Basically, any game objects that want to participate in collision detection have to implement this interface, then register themselves with the detector, which maintains a list of ICollideables. When it detects a collision, it calls the HandleCollision method on the object and passes in a reference to the object it collided with.
I like this, because it lets me keep all my collision algorithms in one place, and lets the game objects themselves decide how to handle the collision. But because of the latter, I find I am having to check the underlying object type. For example, I don't want Players to collide with each other, so in the Player class there might be something like:
void HandleCollision(ICollideable collidedWith)
{
if (!(collidedWith is Player)) { // do stuff }
}
and so on, and I am wondering if this is telling me that I have a bad design and what the alternatives might be.
Second question, further along the lines of the first. For scoring purposes, if an Enemy is destroyed by a Projectile, someone needs to know the "Owning Player" member of the Projectile class. However, none of my other collideables have or need this property, so I find myself wanting to do (in the Enemy HandleCollision):
void HandleCollision(ICollideable collidedWith)
{
if (collidedWith is Projectile) {
Health -= collidedWith.Damage;
if (Health <= 0) {
Player whoDestroyedMe = (collidedWith as Projectile).FiredBy
// ...
}
}
}
I haven't a clue as to how to handle this with a better design. Any insights would be appreciated.
EDIT: I wanted to pull focus towards the second question, because my gut tells me a way of handling this will solve the first question. As for the first question, I thought of a way to abstract this behavior. I could define an enum:
enum Team
{
Player,
Enemy,
Neither
}
and have ICollideables implement this property. Then the collision detector simply doesn't register collisions between collideables on the same "Team". So, Player and Player Projectiles would be on one team, Enemy and Enemy Projectiles on the other, and the environment (which can damage both) can be on neither. It doesn't have to be an enum, could be an int or a string or anything, with the idea that objects with the same value for this property do not collide with each other.
I like this idea of modeling behavior with a simple attribute. For instance, if I want to turn "allow friendly fire" on, all I have to do is create Projectiles with a Team value other than the Player's Team value. However, I still may have cases where this is not enough. For example, a Player may have shields that are temporarily impervious to projectiles but will not protect against a direct collision with an enemy, and so on.

I think you're going the wrong way altogether in handling the collision inside of the class of one of the colliders. I would put this logic into a third object, outside of the entity objects. You could do all of the checking of the types in this third object, and even handle most of the logic there too. Why should a Ship or a Projectile have a monopoly over the logic that happens when one hits the other?
The following is how I might handle this, although it means using an object for each style of collision (Ship vs Ship, Ship vs Projectile, Ship vs Asteroid, etc.) You might be more comfortable putting all that logic into a single object, or even a single method on that object.
public interface ICollisionHandler
{
bool HandleCollision(Entity first, Entity second);
}
public class PlayerShipVsProjectile : ICollisionHandler
{
private GameOptions options;
public PlayersOwnShipHandler(GameOptions options)
{
this.options = options;
}
public bool HandleCollision(Entity first, Entity second)
{
// Exactly how you go about doing this line, whether using the object types
// or using a Type property, or some other method, is not really that important.
// You have so much more important things to worry about than these little
// code design details.
if ((!first is Ship) || (!second is Projectile)) return false;
Ship ship = (Ship)first;
Projectile projectile = (Projectile)second;
// Because we've decided to put this logic in it's own class, we can easily
// use a constructor parameter to get access to the game options. Here, we
// can have access to whether friendly fire is turned on or not.
if (ship.Owner.IsFriendlyWith(projectile.Shooter) &&
!this.options.FriendlyFire) {
return false;
}
if (!ship.InvulnerableTypes.Contains(InvulnerableTypes.PROJECTILE))
{
ship.DoDamage(projectile.Damage);
}
return true;
}
}
Like this, you can then do...
// Somewhere in the setup...
CollisionMapper mapper = new CollisionMapper();
mapper.AddHandler(new ShipVsProjectile(gameOptions));
mapper.AddHandler(new ShipVsShip(gameOptions));
// Somewhere in your collision handling...
mapper.Resolve(entityOne, entityTwo);
The implementation of CollisionMapper is left as an exercise for the reader. Remember that you might need to have Resolve call the ICollisionHandler's "Handle" method twice, with the second time reversing the entities (otherwise your collision handler objects will need to check for the reverse situation, which might be ok as well).
I feel this makes the code easier to read. A single object describes exactly what will happen when two entities collide, rather than trying to put all this info into one of the entity objects.

For the first case, I would add the following extra method to ICollidable:
bool CanCollideWith(ICollidable collidedWith)
As the name suggests, it would return true or false depending upon whether it can collide with the passed in object.
Your Player.HandleCollision method would just do its stuff because the calling method could do that test and not even call the method if it wasn't required.

How about something like this?
Collidable.cs
abstract class Collidable
{
public Sprite Sprite { get; protected set; }
public int Damage { get; protected set; }
protected delegate void CollisionAction(Collidable with);
protected Dictionary<Type, CollisionAction> collisionTypes = new Dictionary<Type, CollisionAction>();
public void HandleCollision(Collidable with)
{
Type collisionTargetType = with.GetType();
CollisionAction action;
bool keyFound = collisionTypes.TryGetValue(collisionTargetType, out action);
if (keyFound)
{
action(with);
}
}
}
Bullet.cs
class Bullet: Collidable
{
public Bullet()
{
collisionTypes.Add(typeof(Player), HandleBulletPlayerCollision);
collisionTypes.Add(typeof(Bullet), HandleBulletBulletCollision);
}
private void HandleBulletPlayerCollision(Collidable with)
{
Console.WriteLine("Bullet collided with {0}", with.ToString());
}
private void HandleBulletBulletCollision(Collidable with)
{
Console.WriteLine("Bullet collided with {0}.", with.ToString());
}
}
Player.cs
class Player : Collidable
{
public Player()
{
collisionTypes.Add(typeof(Bullet), HandlePlayerBulletCollision);
collisionTypes.Add(typeof(Player), HandlePlayerPlayerCollision);
}
private void HandlePlayerBulletCollision(Collidable with)
{
Console.WriteLine("Player collided with {0}.", with.ToString());
}
private void HandlePlayerPlayerCollision(Collidable with)
{
Console.WriteLine("Player collided with {0}.", with.ToString());
}
}

I think this is a good question #idlewire and I have to say that I don't think there is anything fundamentally wrong with your original solution. In asking whether object Foo should be allowed to cast the ICollideable to a Bar, the important question is only: is undesirable to have Foo knowing anything at all about Bar? If the answer is 'no' because Foo already knows about Bars (for behaviours other than collisions, perhaps) then I see no problem in the cast and, as you say, it allows you to better encapsulate the behaviour of both.
Where you need to be wary is only where this would introduces a dependency between two things you'd like kept apart - which would make re-use of either without the other (in a different game application for example) impossible. There you might want to either have more specific sub-interfaces from ICollideable (e.g. IElastic and IInelastic), or use properties on the interface as you have proposed with the Enum.
In short, I think your original posting shows good evidence of OO thinking, not bad.

Sometimes the simplest method is the best method. Unless you want to separate your collision interactions into numerous subtypes, you could instead place a bool IsPlayer property within the Interface.
The upside here is that you have a cheaper, and type safe method of determination over casting.
If (isplayer == true)
{
Handlethisway;
}
The downside is that you're still having to do some sort of state checking, but this is more efficient.
To avoid any state checks, you'd need to do the following: Make an ICollidablePlayer Interface which accepts generic Icollideable and handles them differently. Since the Icollideable is your injected dependency, the ICollideablePlayer dependencies are inherent. The objects of Icollideable would have no knowledge of this separate process, and interact with each other in the same manner.
ICollideablePlayer:ICollideable
{
//DependenciesHere
HandlePlayerCollision(ICollideable)
{
HandleDifferently
{
}
ICollideable
{
//DependenciesHere
HandleCollision(ICollideable)
}
}
}
In an interaction, the ICollideable will treat the player as any other ICollideable, but the ICollideablePlayer will reject the interaction when it does the check itself.
For things like shields and all that, You're talking about state changes which implies that those such things should be properties within either of those Interfaces such that something like bool ColliderOff to temporarily change the state.