Reading texture from texture atlas by name or path

Questions & Answers
1

I need to create a texture Atlas dynamically, so I have used Texture2D.PackTextures to pack all textures in a folder named “Images” in my Resources folder.

Texture2D[] atlasTextures = Resources.LoadAll<Texture2D>("Images");

            Texture2D atlas = new Texture2D(4096, 4096);
            Rect[] rects = atlas.PackTextures(atlasTextures, 2, 4096);

            string atlasDirPath = Application.persistentDataPath + "/Resources/Images";
            if (!Directory.Exists(atlasDirPath))
            {
                Directory.CreateDirectory(atlasDirPath);
            }
            FileStream fs = new FileStream(atlasDirPath+"Atlas.png", FileMode.Create);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Write(atlas.EncodeToPNG());
            bw.Close();
            fs.Close();

So an Atlas Images is perfectly generated and saved in the persistent path.
Now, I need to get a particluar texture individually and convert it to sprite and add it to spriteRenderer in my scene. But to select a texture, I only have the name/path of the texture.
But Texture2D.PackTextures returns Rect array.
Now I don’t understand how should I pick a particular texture from the atlas with me only having the name of the texture.

2

In theory, the rect array returned from the packing function should match the order of the input textures - as such, if you were to also cache the source textures (or at least some of their data) you would be able to use that and match the textures up with their positions;

Dictionary<string, Rect> m_AtlasTextures = new Dictionary<string, Rect>();

...

Texture2D[] atlasTextures = Resources.LoadAll<Texture2D>("Images");

Texture2D atlas = new Texture2D(4096, 4096);
Rect[] rects = atlas.PackTextures (atlasTextures, 2, 4096);

for (int i = 0; i < atlasTextures.Length; i++)
{
    // Cache each texture rect by its corresponding texture name
    m_AtlasTextures[atlasTextures_.name] = rects*;*_

}

…

// Then, you can fetch the texture coordinates like so
public Rect GetAtlasTextureCoordsByName (string a_TextureName)
{
return m_AtlasTextures[a_TextureName];
}
I have not tested this, but I can’t imagine the rect array not matching the order of the input textures, otherwise the data would be useless - there would be no way of knowing what element a rect would be pointing to.