Script for exporting Unity sprite packer atlas texture.

SpriteAtlasExporter.cs

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

public class SpriteAtlasExporter : MonoBehaviour {

    public Sprite sprite;

    RenderTexture tex;

	void Start () {

        var stex = sprite.texture;
        Debug.Log(stex.width + " " + stex.height);

        tex = RenderTexture.GetTemporary(stex.width, stex.height, 0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Default);
        tex.Create();


        Graphics.Blit(stex, tex);

        SaveToFile(tex, Application.dataPath + "/" + stex.name + ".png");

        RenderTexture.ReleaseTemporary(tex);


    }


    public static void SaveToFile(RenderTexture renderTexture, string name)
    {
        RenderTexture currentActiveRT = RenderTexture.active;
        RenderTexture.active = renderTexture;
        Texture2D tex = new Texture2D(renderTexture.width, renderTexture.height);
        tex.ReadPixels(new Rect(0, 0, tex.width, tex.height), 0, 0);
        var bytes = tex.EncodeToPNG();

        Debug.Log(name);
        System.IO.File.WriteAllBytes(name, bytes);
        UnityEngine.Object.Destroy(tex);
        RenderTexture.active = currentActiveRT;
    }




}