Object spawning and deleting - unity3d

I am currently making a simple side-scroller. In unity. I am looking for a way to spawn objects before they enter camera, and remove them after they have passed the camera. All this will happn in the x axis.
There are 6 different kinds of objects that are going to be spawned. and with different distence from each other.
The objects can be picked up, and they are all prefabs and have the functional scripts for pickup if the player collide. But I need a way to remove them if they didn't get picked up.
Is there anyone that have a simple script where this will be possible?

there is a 2 methods in MonoBehaviour you can use: OnBecameInvisible and
OnBecameVisible. they are called whenever the renderer is no longer visible (or becone visible) by any camera.

Related

Unity 2D: physics-based pathfinding package/library

I'm working on a small project where the goal is to defend yourself from mass enemy hordes in a 2d environment. The goal is to have the game be physics based, with enemies pushing against eachother to create a feeling of chaos.
Now I have a setup with enemies, a player and multiple obstacles all with a Rigidbody2D and 2D-colliders (mixed types, including polygon2D collider). Now I want to have the enemies chase the player. The obstacles however are polygon shaped rigidbodies, and thus are able to move.
So I want the "navigation" mesh of some sort to update on the fly, and calculate a navigation path for many entities.
Note: I don't know how many entities yet, but let's say ~100.
The things I tried to far:
Using the built-in NavMesh package from Unity. This package does not properly support the 2D configuration of Unity
Using the NavMeshPlus package. This implements a NavMeshSurface2D component to work with the 2D environment. I got this to work, but the NavMeshAgent component to steer the enemy does not use the force attribute of the rigidbody component, but rather just sets the speed or position of the transform. If someone knows how to use the NavMeshAgent or the NavMesh API in a way to get the target direction/speed via script, that would also be a solution
I tried the A* package. Which also works, but creates a very jagged line as it only can move in 8 directions (up,down,left,right and diagonals). It also cuts the corners of the obstacles, and does not take into account the size of the object (enemy) itself, so it hangs at the corners.
If anyone knows a good package/extension or the location of documentation of the NavMesh part, that would be great!
Thank you in advance.
So I got it to work and will share the solution I took:
Using the NavMeshPlus package, I created a navmesh.
Instead of using a NavMeshAgent, I configured an agent type in the navigation window with the right physical dimensions.
Next I added a script on the enemy to function as a custom NavMeshAgent.
Add a NavMeshSurface2D reference to the script (Serialized)
Using UnityEngine.AI, call NavMesh.CalculatePath(), with the AI.NavMeshQueryFilter. This has 2 components, the agent and area setters. Both of those I get from the NavMeshSurface2D reference.
Now you have the path the agent has to follow!
By the way, I'm also aware this could be done by a custom Agent inheriting the NavMeshAgent class, I'm also looking into that. Time will tell which one will have better performance.

Does changing multiple sprites on a single animation affect performance?

I have been building a 2D sprite based game for which I want to have the player be able to customize their equipment. This means that although I am fine with drawing the content, I'd need to ensure animations in the game run fine on top of each other. For this, I have been preparing a game object with several children to account for the equipment:
Each of the children runs a single animation and should have to follow the player, which I accomplish by using transform.localPosition = Vector2.zero; on the Update of the script each takes, so they hook to the parent's pivot and follow the player. While this has worked for the most part, there are moments in which all of the objects are not synchronized and as such sometimes the parent object (the body) is seen where it shouldn't since the other game objects should render on top:
Aside from that, to make it easy for the children to follow the parent position I had made sprites which are all the same size, which risks me having to load a lot of transparent space per sprite.
Another problem that I just noticed as I'm trying to address the issue of loading too many useless pixels involves the positioning with other objects such as the Sword game object, which doesn't follow the player fully if I use sprites that are not perfect squares (see this question for details How to align sprites of smaller sizes to a moving gameobject sprite? and this one Sibling sprite doesn't appear to follow main GameObject sprite even when transform.position updates)
I tried to fix this by making the Sword a child of the Hero, but even then changing the position through a function that sets values to add on to transform values of the sword game object only change the position of it relative to the initial value. I attempted changing the pivot of the sword sprites to a custom value to guess where the center of it would align with the main game object and appear in the right position, but even that doesn't seem to work.
I'm kind of getting tired with my current process, as I have to rely on several animations for each of the game objects, both parent and children, so that these obey to different layers in a single animator (or in the case of the sword, a separate animator), all to ensure there is some synchronization that doesn't always occur:
I really don't mind the web that is turning out in what I'm doing, but the fact that I have to repeat it across multiple layers with no real guarantee that all the objects would appear right on top of each other due to the fact of having multiple animations playing, and loading multiple sprites with empty space is becoming more of a chore than enjoyment.
So I think I came up with a possible solution: If I could make a single animation for the whole equipment used at any given point (whether only wearing pants or wearing full equipment), then having this single animation could guarantee synchronization across parent and children without the need for animator layers or special functions to update position or worrying about pivots or square sprites if I can set the position of non-square sprites in the animation, with the downside that I would need to account for every single animation for each possible equipment variation (so if I had even 3 of each sword, pants, boots, etc. that would mean 3^6 animations) and make a more complex web of animator states. The only thing I'd be worried about in this case, however, would be the performance, if having too many animations for a player would affect how fast these load. But at the benefit of eliminating the other problems mentioned, my question boils down to this:
Is it better to have a single game object with animations that change multiple sprites across children game objects and a single animator that chooses states based on multiple variables, or game objects with multiple animations that change a single sprite for each, and a single or multiple animators with multiple layers that choose states based on multiple variables?
There isn't really a set answer for something like this. It really just depends on how good your/the players computer is when playing the game. Sorry if this isn't what you wanted.

Unity best practice: How to represent (hold and pass) the game items/enemies/attacks/etc? as scriptable-objects or prefabs?

I want to create a game with tons of different enemies, items, accessories, heroes, attacks and more.
To make it easily expandable and maintenance, I want to create the game in the most modular way possible so nothing in the game will be built-in and every aspect of the game will be assembled and configured.
But I'm undecided as to how the elements should be modeled:
As ScriptableObjects - (for example) every enemy will be configured and represented by some scriptabe-object and this asset will contains the enemy stats and behaviours but also the enemy prefabs so the script will tell us how to create the enemy object in the game.
so if I have some place that I want to put some enemy in it, I should (for example) attach on the inspector the enemy's scriptable-object.
As Prefabs - every enemy will be represented by some prefab and the prefab root object will contains some scriptable-object that its purpose is to hold some specific enemy stats and behaviours and the enemy will be act according to them.
so if I have some place that I want to put some enemy in it, I should attach on the inspector the enemy's prefab.
Is there some best practice for that? a way that will make my life easier when the game will be particularly large and complex?

How can I access an object's components from a different scene?

I have a Player gameObject that has a script on it which keeps some variables inside it. I created a scene which acts as a main menu and has "Shop" part in it, which has upgrades in it, basically I need to access Player gameObject's script from a different scene so I can modify variables from main menu scene. How can I do that ?
check this out:
https://docs.unity3d.com/ScriptReference/Object.DontDestroyOnLoad.html
once your player is loaded this will keep him in every scene until you choose to release hiim, meaning when you load your menu scene he will be there to access.
now since we know hes there, we can:
(note that player is your script with the variables not your actual player)
ScriptName player = GameObject.FindObjectWithTag("yourtag").GetComponent<ScriptName>();
Be default the components are instances of a class. If there isn't a GameObject with that component in the currently loaded scenes, there is nothing to access.
If I recall you can now load more than one scene at a time.
If there is a GameObject with that script currently loaded you can use:
https://docs.unity3d.com/ScriptReference/Object.FindObjectsOfType.html
or even better
use singleton design pattern, in case you have only 1 player at a time.
I guess you want to save these upgrades for the next run of the game, so you can use PlayerPrefs
https://docs.unity3d.com/ScriptReference/PlayerPrefs.html
If you want to save more than 50 values of data I would suggest using a file based DB like SQLite, it takes little time to setup and works very fast. And it is a lot more readable than using PlayerPrefs.
How about static class?
You can keep values there and access it from any place you want :D

Having multiple unity scenes open simultaneously

I've been developing a board-style game in Unity3D. The main scene is the board, and has the data about each player and the current (randomly-generated) board stored within it.
I intend to add minigames into the game, for example when landing on a particular space on the board. Naturally, I would like to code the minigame in a separate scene. Is there a way I can do this without losing the instance of the current scene, so that the current scene's state is maintained?
Thanks in advance :)
Short answer: no, but there may be another way to do what you want.
A basic call to Application.LoadLevel call will destroy the current scene before loading the next one. This isn't what you want.
If your minigame is relatively simple, you could use Instantiate to bring in a prefab and spawn it far away from the rest of your scene. You can even use scripts to switch to another camera, toggle player controls and other interactions in the scene, and so on. Once the minigame is done, you can destroy or disable whatever you brought in, and re-enable whatever needs to be turned on in the main scene.
You could create a separate scene and call Application.LoadLevelAdditive to load that scene without destroying the current one. As above, you can then use scripts to manage which cameras and scene behaviors are active.
If you're careful, you don't really need two separate scenes. It may be enough to "fake" a scene switch.
Hard to give a complete answer without code, but you should look into the following things either with the unity documentation or youtube:
PlayerPrefs, this is one way of saving data, although i believe it isn't entirely secure i.e. being able to edit from a text file.
Serializable, this is apparently better than playerprefs.
DonDestroyOnLoad, can carry over information to multiple scenes.
Static variables, again not sure if this will help your particular problem.