Tag: Scriptable Objects

Frogger Remake & SODA

C#, Development Samples, Programming Samples

Hello all, I hope that this blog post finds you all well. Given the COVID-19 circumstances, I (and everyone I know) have been pushed into online classrooms. It’s been fine, but luckily it has also given me some personal time to try and post on this site, and work on more personal projects… That being said this post is a class project by Nicole Havin, and myself. Nicole worked on the mostly on the aesthetic side of things, implementing sounds, Timer UI and Main menu. I’m writing this post to talk more about Scriptable Object Dependent Architecture. I’m posting this game here to provide my readers with an opportunity to experience the architecture of which I will be writing about.

Disclaimers: I do not own anything in this game

This is a remake, for a class project, of Konami’s 1981 classic “Frogger”

https://simmer.io/@aidantakami/~bcd44750-53b0-3b08-07fd-bcb7b3778673

This game is buggy and was made under a time crunch for class. I am only posting this game here to give examples of the architecture I am speaking of, and showing how it is used in this specific build. I am also experimenting with UnityWebGL and trying to get those games hosted here on my site. For those who don’t know, exporting to UnityWebGL carries with it a plethora of issues in how the game in converted to be playable via a browser. There are certainly lots of bugs which I have not run into on the WebGL version. So please consider this as you play this game! Please feel free to contact me if you find any bugs! If this goes well I will continue to try and import playable demos of the architecture of which I’m writing about. Give it a few plays through and I’ll catch you on the other side.

This short experience is build to be modular, easily debuggable, and dependency free through the use of SODA Game Events & Listeners, and SODA Variables.

I’d like to first draw your attention to how when the player is in the first half of the map they must avoid collisions. Collisions here are from incoming cars, which are deadly to frogger. However, the second half of the map, this is flipped. The second half of the map the player must seek collisions. Collisions in the latter half of the map are from the stable log platforms or the finish line colliders.

So how might we “normally” do this? I would say it would involve an edge trigger collider that would tell the player script that it needs to collide or else die. But alas, the eternal game dev issue of detecting if something isn’t there, in this case that something would be the log. I don’t want to get into how we might complete “this” way of solving the issue, but it’s just messy and involves heavy dependencies.

What is the SODA way of doing this? I appreciate you asking. Imagine if we could just have a Scriptable Object which holds a bool value, and we call it BoolVariable “isOverWater”. We set up a collider at the edge of land and water and have that trigger toggle between the 2 states of isOverWater, true and false. Now how do we get logs in there? Simple, the same thing, just have a single BoolVariable, playerIsOnMe, which all log prefabs reference. Does that make sense? This single variable is being operated on by all instances of the log prefab. These logs simply set the variable to true OnTriggerEnter() and to false OnTriggerExit(). Here’s that code:

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

public class LogScript : MonoBehaviour
{

    //BoolVariable to represent if player is on this log
    public BoolVariable playerIsOnMe;

    //Used for spawning purposes
    private bool startsOnRight;
    public SpriteRenderer sr;

    //Used to move the player when on log
    [SerializeField]public IntVariable logSpeedToPlayer;
    [SerializeField] public int logSpeed;


    //Flips sprite depending on start side
    private void Start()
    {
        if(transform.position.x > 0)
        {
            startsOnRight = true;
            sr = gameObject.GetComponent<SpriteRenderer>();
            sr.flipX = true;
        }
    }

    // Update is called once per frame
    void Update()
    {
        //Moves the log in accordance to where it was spawned
        if (!startsOnRight)
        {
            transform.position += transform.right * logSpeed * Time.deltaTime;
        }
        else
        {
            transform.position -= transform.right * logSpeed * Time.deltaTime;
        }
    }


    public void OnTriggerEnter2D(Collider2D col)
    {
        //Player enters log
        if (col.gameObject.CompareTag("Player"))
        {
            //Set BoolVariable value
            Debug.Log("Player is on");
            playerIsOnMe.SetValue(true);

            //Gives this logs speed to the IntVariable which gives it to the Player
            if (!startsOnRight)
            {
                logSpeedToPlayer.SetValue(logSpeed);
            }
            else
            {
                logSpeedToPlayer.SetValue(-logSpeed);
            }
        }
        
    }

    public void OnTriggerExit2D(Collider2D col)
    {
        //Player Leaves Log
        if (col.gameObject.CompareTag("Player"))
        {
            Debug.Log("Player is off");
            playerIsOnMe.SetValue(false);
            logSpeedToPlayer.SetValue(0);
        }
        
    }
}

If this makes any sense to you, then odds are you can understand what is going on in the rest of this script (beyond the OnTriggers), but more on that later. The main note here is that when the player enters the log, beneath the Debug statement, the BoolVariable playerIsOnMe is set to true. This lets the player movement script know to continue displaying the idle sprite, this bool lets the GameManager know the player is still alive. These BoolVariables (playerIsOnMe and isOverWater) are both accessible by all other scripts, and never providing conflicting values because all scripts are refrencing the same ScriptableObject.

How are these two BoolVariables being compared? Once again, well thought out question. So since both these Bools are being determined elsewhere in the script, our PlayerMovement script, which also serves as the animator controller, simply has to reference these 2 variables values to know the state of the player. I did this in Frogger by having an event at the end of every “Jump” animation which would check the state of the 2 BoolVariables, as at the end of the Jump animation the player would either be securely on a log or dead.

About the IntVariables: If you understand the above architecture then you’ll enjoy knowing what’s going on with the IntVariable logSpeedToPlayer in the above code. Basically, that IntVariable, when set to 0, will not affect the player’s movement at all. When set to x it will apply a constant drag to the player to the right to simulate the effect of the player being on the log. So… Do you see why this is so rad? I can just SET THIS INT in my LOG SCRIPT and then my player will INSTANTLY BE EFFECTED by the change to this variable! COME ON!!! How Cool?! So notice that logspeed is just a regular int, but it is used to set the value of logSpeedToPlayer when needed. For now, that’s it! I will try to be more present on here, but I’m busy! But I hope you enjoy! and stay safe!

Scriptable Object Events in Unity and My Cutscene Manager

C#, Development Samples, Programming Samples, Unity Projects

Hello all. Finals season is over, and I have the most persistent cold I’ve ever experienced… which means I have a lot of time. Luckily, I’ve been working on this project with my friends and had the opportunity to write some really cool code that I’d like to share here. The other engineer on the project, and myself have been trying to build the architecture of this game utilizing a very powerful tool: Scriptable Objects. If you don’t know what these are, I highly recommend watching this talk by Ryan Hipple. TL;DR You can utilize Scriptable Objects to store data, as opposed to individual method calls and dependencies within code, to keep the architecture modular, easily debuggable, and less prone to collapse on you. A Scriptable Object will store a variable and allow any function to access it, or modify it, so that all methods can just respond to this one value. Think “global variable” that exists in the editor.

Another very cool principle in the talk by Ryan is using Scriptable Object Game Events (which take the same above principal, but utilize UnityEngine.Events;) to interface between everything in the scene that would otherwise be dependent through code. So here’s what I wrote: A cutscene manager for my game using Unity Timeline and Scriptable Object Game Events.

How it works: I have a UnityEvent StartScene that is Invoked OnTriggerEnter().

public class StartCutscene : MonoBehaviour
{

    //Event to start scene
    public  UnityEvent startScene;


    //on trigger enter
    private void OnTriggerEnter(Collider other)
    {
        //if player
        if(other.tag == "Player")
        {
            //raise
            startScene.Invoke();
            Debug.Log("Invoked");

        }
    }

}

Then this is what it looks like in editor. As a matter of fact, take my whole “CutsceneTrigger” prefab while you’re at it:

Note the UnityEvent is calling on the Game Event Scriptable Object “PlayCutscene” and Raising it. This signals to any Game Event Listeners (Once again, a Scriptable Object implementing the functionality of a Unity Game Event Listener) elsewhere in the scene that were set to listen to our Game Event Scriptable Object. In this case, I have 2 prefabs listening in on “PlayCutscene”. The first one is my CutsceneManager.

So take a nice long look at that beauty, and I think you might fully see what’s going on here. First off, I have the Game Event Listener which is making a call within my CutsceneManager Script to startNextCutscene(). startNextCutscene utilizes a Dictionary, which I have serialized at the top of the prefab. This dictionary takes the string name and the associated PlayableDirector, which is what controls Unity Timeline Playables. If you’re familiar with Dictionaries then you know they’re not serializable in Editor, but we can fix that with a nifty little work around in code. 

//Serialized Dictionary Class
[System.Serializable]
public class Cutscenes
{
    public string cutsceneName;
    public PlayableDirector cutscene;

}


//Cutscene Manager will play the next applicable cutscene, storing all in a dictionary
public class CutsceneManager : MonoBehaviour
{

    //Note to design
    [TextArea]
    public string Notes = "Names should have no spaces or numbers and triggers should be place in order of encounter";

    //Array of Cutscenes, which contain our Dictionary compontents
    public Cutscenes[] toDictionary;

    //Dictionary that takes string name and PlayableDirector
    public Dictionary<string, PlayableDirector> listOfScenes;

    //Int to monitor which have played
    private int selection;

    //Unity Event to on trigger end of scene
    public UnityEvent endCutsceneEvent;


    //establishes Dictionary from serialized "Cutscenes"
    public void Awake()
    {

        //Instantiates Dictionary
        listOfScenes = new Dictionary<string, PlayableDirector>();

        //Fills that shit up
        for(int rep = 0; rep < (toDictionary.Length); rep++)
        {
            listOfScenes.Add(toDictionary[rep].cutsceneName, toDictionary[rep].cutscene);
        }


    }



    //Starts next cutscene
    public void startNextCutscene()
    {

        //Sets temp Playable Director
        Debug.Log("Signal Recieved");
        PlayableDirector temp = listOfScenes[toDictionary[selection].cutsceneName];


        //Starts cutscene
        Debug.Log("Starting...");
        temp.Play();

        //Event "stopped" is assigned to endCutscene, will call this function on raise
        temp.stopped += endCutscene; 
 
        //Increments cutscenes
        selection++;



    }

    //Invokes UnityEvent to tell rest of scene
    private void endCutscene(PlayableDirector aDirector)
    {
        //Ends the cutscene
        endCutsceneEvent.Invoke();

        Debug.Log("Cutscene Ended");
    }

}

So I’ll try to break this down for those who can’t understand my comments, but basically at the very top we have the serialized class Cutscenes, which I’m taking all the components necesary for my dictionary. Then storing them in an array toDictionary. Then, on Awake() I’m taking those individual values from the array and storing them together in my Dictionary ListOfScenes. Also note that I have a UnityEvent here at the top.

So this is where startNextCutscene() comes into play. I take the next PlayableDirector in order and store it in my temp, but note how in the search through my Dictionary ListOfScenes I’m using the corresponding string stored in the Array toDictionary to index the needed PlayableDirector. Just thought that was sick. A little wonky… but cool.

Then temp is played, which cues the animation sequence of the PlayableDirector, otherwise known as the Playable. The PlayableDirector then sets off an event upon finishing which I’m listening to and invoking my own UnityEvent endCutsceneEvent.

This is where my CameraManager comes in. Note that in the above picture of my CutsceneManager Prefab, my Unity Event endCutsceneEvent is attached to another Scriptable Object Game Event “EndCutscene”

From the bottom up, the CameraManager is listening to 2 events, EndCutscene and PlayCutscene. Remember, these are our scriptable events, any listener in the scene has access to them! So these are both invoking responses within my CameraManager script. At the top you can see the manager takes 2 Cameras, as this script is responsible for switching between the cutscene camera, used in our PlayableDirector Playables, and the main camera, used for gameplay. Don’t worry, this is not the only script working on the camera right now, this is just helping us manage between the 2 specifically with Playables. Here’s that code:

[System.Serializable]

public class CameraManager : MonoBehaviour
{

    //Declares the cameras needed
    public Camera playerCam;
    public Camera cutsceneCam;

    public void Awake()
    {
        switchAfterCutscene();
    }


    //Starts the cutscene, swapping cameras
    public void cutsceneStart()
    {

        //Cameras swapped
        switchBeforeCutscene();
        
        //Debug
        Debug.Log("play cutscene");


    }

    //Ends the cutscene, swapping cameras
    public void cutsceneEnd()
    {
        //Cameras swapped back
        switchAfterCutscene();

        Debug.Log("Cutscene end");
    }


    //Swaps active cameras
    private void switchBeforeCutscene()
    {
        playerCam.enabled = false;
        cutsceneCam.enabled = true;

    }

    //Swaps active cameras
    private void switchAfterCutscene()
    {
        cutsceneCam.enabled = false;
        playerCam.enabled = true;
    }
}

Pretty self explanatory, but just note that the methods switchBeforeCutscene() and switchAfterCutscene() are both triggered by the corresponding Game Events in scene, in addition to the startNextCutscene() in the CutsceneManager. I wanted to show you to give an example of how using GameEvent Scriptable Objects allows multiple scripts to interface with one another without ever knowing the other exists!

You have to see how this is such a god send for devs who want to keep dependencies low and the engine easy to use for designers. Here, a designer who has been briefed can easily establish a whole system of cutscenes in their level without ever having to see a single class.

Happy holidays to everyone! I’ll be back soon with more.