How to know if a sprite is loaded from a SpriteAtlas or from the original asset?

Unity Engine
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1

Imagine this scenario :

  1. I have one PNG that I imported as Sprite (2D UI)
  2. I have created a SpriteAtlas in my Assets/ folder
  3. I have added the sprite inside the PNG in my SpriteAtlas
  4. I put a SpriteRenderer in a scene.
  5. I start this scene.

A) How can I know if the sprite is loaded from the SpriteAtlas or from the PNG ?
B) How can I be sure it’s the SpriteAtlas or the PNG that is loaded in my memory ?

2

You can check the Frame Debugger or Inspector (texture preview).

In code, print the texture name:

var sr = GetComponent<SpriteRenderer>();
Debug.Log("Source Texture: " + sr.sprite.texture.name);

If it’s a single sprite it will print the sprite’s name, otherwise that of the SpriteAtlas.

3
  • Frame Debugger only shows me one render pass with a white texture
  • the Inspector when I click on the “Sprite” that is in my SpriteRenderer Component, points me to the original PNG
4

I tried with the Memory Profiler (in editor) and it is referenced three time :

[Album] imgur.com
  1. Once by the Sprite Atlas
  2. Once by the PNG
  3. once by “sactx-0-…” which I don’t know what it is…
5

I tried this code and it gives me
“Source Texture: sactx-0-4096x4096-ASTC 6x6-R3L4 - Cave - Atlas-ff29e3c8”
which seems to be the atlas I guess.

Which answer in my case :

  • The PSD Importer creates a Sprite Atlas itself if you have multiple sprites inside (multiple layers)
  • In my case, putting every single sprite from a PSD into a Sprite Atlas makes a better Atlas than the Atlas generated from the PSD Importer.
6

Worth noting that the Sprite itself remains as is, whether atlas or single. The Sprite reference is lightweight though. That third reference could be - but I’m not sure - simply a sprite frame reference meaning it represents the portion of the atlas texture from which the sprite is drawn. I believe this is still technically a texture type in Unity but it shares the atlas’ texture memory, it’s not a copy of the texture.