Dump RenderTexture to PNG in Unity

DebugUtil.cs

public static class DebugUtil
{

    public static void DumpRenderTexture(RenderTexture rt, string pngOutPath)
    {
        var oldRT = RenderTexture.active;

        var tex = new Texture2D(rt.width, rt.height);
        RenderTexture.active = rt;
        tex.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
        tex.Apply();

        File.WriteAllBytes(pngOutPath, tex.EncodeToPNG());
        RenderTexture.active = oldRT;
    }

}