Aligning a card array in-game - arrays

Question

I'm creating a tcg (trading card game) and I would like to know how can I change the layout of the cards while playing. I mean that the cards will be spread in line aligned to the center of the screen both vertically and horizontaly, on a canvas, and when I draw/dismiss a card I would like the cards to fill in the space and align again in game. How can I do that? any ideas? I thought of a solution about when your turn begins (Start from the center of the screen then step back the length of a step X the number of cards / 2 and then spawn the cards one after another), but I can't figure out how to change the alignment of cards when you dismiss one of them without loading them all again...
Image for example

Answer 1

Using the same method you used for the initial position you should be able to get the new position. Now you have two positions for each card: oldPos and newPos.
Your cards are already instantiated. Their positions are stored in Transform.position. Your goal is to move from oldPos to newPos. The simplest way would be:
myCard.transform.position = newPos;
This will instantly move your cards to their new positions. However, it's not common to teleport your objects because it does not often present good feelings to users. A better solution is to smoothly move the object from a position to another.
To do this, you can move around an existing object by transform.Translate(new Vector3());, where the Vector3 will decide its moving speed. The method Translate() is doing position += movementDirection * movementAmount as you would've expected.
Moving any object over frames is called Animation. There are techniques for animation to make movements look more better (look faster than it really is, or look natural). One common method from mathematics is called linear interpolation, or lerp. Using lerp, you can easily compute intermediate points between two end-positions, and it will look natural and nice if you put your objects along the points you calculated. I believe this is what you are looking for.
========
Edit:
Here's an example of how this could be achieved. Note that Card is moving by the same amount of distance per frame in this example. Using lerp (ease-in, ease-out, etc), you could make this animation even better.
Another point I would like you to note is that I'm doing if (Vector2.Distance(nextPosition, transform.position) < 10), not if(oldPosition.equals(newPosition)). The reason is that equals() is not safe to compare floats because they are often stored as 0.4999999 and 0.50001 instead of 0.5 and 0.5. So the best way of checking floats is to test if they are "Close Enough" to each other.
Finally, you could improve the following code may improve in MANY DIFFERNET WAYS. For instnace:
Destroy() and Instantiate() is very slow operations and you
should use Object Pooling because you know you will perform these
operations constantly.
The movement of Card could be improved by better animation technique like lerp.
There may be other ways of storing List<Card> Cards
OnCardClick() is using FindObjectOfType<CardSpawner>().OnCardDeleted(this) and this requires Card to know about CardSpawner. This is called Tight Coupling, which is known as evil. There are a lot of discussions you can find why this is bad. A recommended solution would be to use event (better UnityEvent in Unity3d).
CardSpawner.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CardSpawner : MonoBehaviour
{
[SerializeField] GameObject CardParent;
[SerializeField] GameObject CardPrefab;
Vector2 DefaultSpawnPosition = new Vector2(Screen.width / 2f, Screen.height / 10f);
List<Card> Cards = new List<Card>();
public void OnClickButton()
{
SpawnNewCard();
AssignNewPositions();
AnimateCards();
}
public void OnCardDeleted(Card removedCard)
{
Cards.Remove(removedCard);
AssignNewPositions();
AnimateCards();
}
void SpawnNewCard()
{
GameObject newCard = (GameObject)Instantiate(CardPrefab, DefaultSpawnPosition, new Quaternion(), CardParent.GetComponent<Transform>());
Cards.Add(newCard.GetComponent<Card>());
}
void AssignNewPositions()
{
int n = Cards.Count;
float widthPerCard = 100;
float widthEmptySpaceBetweenCards = widthPerCard * .2f;
float totalWidthAllCards = (widthPerCard * n) + (widthEmptySpaceBetweenCards * (n-1));
float halfWidthAllCards = totalWidthAllCards / 2f;
float centreX = Screen.width / 2f;
float leftX = centreX - halfWidthAllCards;
for (int i = 0; i < n; i++)
{
if (i == 0)
Cards[i].nextPosition = new Vector2(leftX + widthPerCard / 2f, Screen.height / 2f);
else
Cards[i].nextPosition = new Vector2(leftX + widthPerCard / 2f + ((widthPerCard + widthEmptySpaceBetweenCards) * i), Screen.height / 2f);
}
}
void AnimateCards()
{
foreach (Card card in Cards)
card.StartMoving();
}
}
Card.cs
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Card : MonoBehaviour
{
public Vector2 oldPosition;
public Vector2 nextPosition;
bool IsMoving;
void Update ()
{
if (IsMoving)
{
int steps = 10;
Vector2 delta = (nextPosition - oldPosition) / steps;
transform.Translate(delta);
if (Vector2.Distance(nextPosition, transform.position) < 10)
IsMoving = false;
}
}
public void StartMoving()
{
IsMoving = true;
oldPosition = transform.position;
}
public void OnCardClick()
{
UnityEngine.Object.Destroy(this.gameObject);
Debug.Log("AfterDestroy");
FindObjectOfType<CardSpawner>().OnCardDeleted(this);
}
}