Create / Modify Texture2D to Read/Write Enabled at Runtime

From here : https://stackoverflow.com/questions/44733841/how-to-make-texture2d-readable-via-script @nyonge , i got this, and it worked well for me :

 Texture2D duplicateTexture(Texture2D source)
 {
     RenderTexture renderTex = RenderTexture.GetTemporary(
                 source.width,
                 source.height,
                 0,
                 RenderTextureFormat.Default,
                 RenderTextureReadWrite.Linear);
 
     Graphics.Blit(source, renderTex);
     RenderTexture previous = RenderTexture.active;
     RenderTexture.active = renderTex;
     Texture2D readableText = new Texture2D(source.width, source.height);
     readableText.ReadPixels(new Rect(0, 0, renderTex.width, renderTex.height), 0, 0);
     readableText.Apply();
     RenderTexture.active = previous;
     RenderTexture.ReleaseTemporary(renderTex);
     return readableText;
 }

"Readonly" only applies to assets that you import at edittime. So if you imported a texture at edittime and you didn't make it readable, you can't read it at runtime and you can't make it readable. So if you need textures which you imported in the editor readable at runtime you have to mark it as readable inside the editor.

Textures created at runtime are always readable unless you pass "true" as second parameter to Apply in which case you made the texture none-readable forever just like an asset that never was.

If you load images at runtime from external sources they also are readable by default

If you want to make something readable, you'd best create a new readable texture at runtime.

If you want to make a read/write texture "static", use: https://docs.unity3d.com/ScriptReference/Texture2D.Apply.html