Trying to code an animation from scratch

Unity Engine
1

As per the title, I’m trying to code an animation from scratch. So I created an object (“GeoObject”) that contains an array of sprites, and has a SpriteRenderer component. Using the WaitForSecondsRealTime() function, I am trying to have GeoObject loop through its sprites at a given rate. But the problem is that, when it comes time to switch, instead of going to the next sprite in the array, the object just starts very rapidly switching between all the sprites. It ends up looking like the object is spazzing out. My code is below and I would really appreciate any help with this.

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

public class GeoObject : MonoBehaviour {

    public Sprite[] shapes;
    public float delay = 2.0f;
    public int spriteIndex = 0;
   
    // Use this for initialization
    void Start () {

        var renderer = GetComponent<SpriteRenderer>();

        // Randomizes the starting shape
        System.Random rand = new System.Random();
        spriteIndex = rand.Next(0, shapes.Length - 1);
        renderer.sprite = shapes[spriteIndex];       
    }

   
    // Update is called once per frame
    void Update () {

        // Falling speed
        float yspeed = -20f;
        transform.Translate(0, yspeed * Time.deltaTime, 0);

        // Loops through shapes
        StartCoroutine(ChangeShape());
    }


    IEnumerator ChangeShape()
    {
        // Pauses execution for however many seconds
        yield return new WaitForSecondsRealtime(delay);

        var renderer = GetComponent<SpriteRenderer>();

        if ( spriteIndex < shapes.Length - 1 ) { spriteIndex++; }
        else { spriteIndex = 0; }

     

        renderer.sprite = shapes[spriteIndex];

       

        StartCoroutine(ChangeShape());

    }
}
2

You’re starting your coroutine in Update, which is called every frame. So you have hundreds of coroutines running in parallel, each one patiently waiting 2 seconds, and then all advancing the sprite.

Start the coroutine in Start instead.

3

That makes perfect sense, thank you!

4

Or, better yet, don’t use Coroutines at all. :slight_smile: Just watch the Time.time and change your sprite image in Update.

But hey, depending on what you’re doing you may find the SimpleAnimator class in my 2D Animation Methods article to be useful.