Unity 4.3 - 2D, how to assign programmatically sprites to an object

Question

I'm trying to create an object that will be responsible of creating and showing different sprites, so I would like to access directly the assets/sprites programmatically instead of drag and drop a sprite in the hierarchy under that object.

There's a way to programmatically create a new sprite and assign what I have in the assets folder?

I also would like to have a sort of data structure with a few images loaded at the start of the game, an array or a dictionary or something like that so I can change based on some situation which images I need to show. But what confuses me since I'm new to Unity is how to create a sprite taking the reference to the sprite programmatically using the assets folder.

edit with progress:

I've created an array of sprites like this:

public Sprite[] mySprites;

in Unity I've added sprites inside the array manually (I just dragged png's inside the variable array) so actually in this Object I have a Component with this array full of sprites

inside the component I also have done this:

public SpriteRenderer renderer;
renderer = transform.GetComponent<SpriteRenderer>();
renderer.sprite = (Sprite)mySprites [0];

I got no error until I run the game, then the sprite is NOT assigned and I got this:

"PPtr cast failed when dereferencing! Castin from Texture2D to Sprite!"

I got this error even without casting (Sprite) and btw I don't know why he is telling my about Texture2D since verything is setted as sprite

Answer 1

To create a sprite programmatically might be a little too difficult to do. You'd probably need to create a Texture in memory, fill in the data, and then write that texture on the disk. After that, you should be able to read that using C#'s File, or Unity's WWW.LoadFromCacheOrDownload.

Here is how you would create a texture dynamically: http://answers.unity3d.com/questions/9919/how-do-i-create-a-texture-dynamically-in-unity.html

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To load your sprites programmatically (not the ones created dynamically though), they need to be under a folder with the name Resources (which is a special folder).

I.e. suppose you have a sprite named MySprite.png under a folder named Sprites which is under a folder named Resources. You would then load it like this:

renderer.sprite = Resources.Load<Sprite>("Sprites/MySprite");

(notice how you do not include the Resources folder and the extension of the sprite)

You can find more details in the Loading Resources at Runtime documentation.

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PPtr cast failed when dereferencing!

I did some searching and found out from this forum post that usually that happens when you had a list of one type and then changed it into another type. I.e. if mySprites was at some point GameObject[] and you linked a bunch of Sprites, and then changed it to Sprite[]. And since it specifically says Texture2D, I'm assuming that the import settings of your Sprites (or some of them) are set to Texture instead of Sprite:

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Also, all MonoBehaviours have already a field named renderer, which is of type Renderer. I would suggest you rename that field to avoid confusion, unless you only used that as an example.

Answer 2

Here is real code.. will help you

void SetSprite(UI2DSprite uiSprite, Sprite[] sprites, string strKey)
 {
     foreach (Sprite stexture in sprites)
     {
         if (stexture.name == strKey)
         {
             uiSprite.sprite2D = stexture;
             break;
         }
     }
 }

use it following the way..

UI2DSprite[] uiSprites = tmpObject.GetComponentsInChildren<UI2DSprite>();
 Sprite[] sprites = Resources.LoadAll<Sprite>("Textures");
 string resName = "icon_favorite_2";

 foreach (UI2DSprite uiSprite in uiSprites)
 {
 if(uiSprite.name = "icon")
  SetSprite(uiSprite, sprites , resName);

 }