I am trying to convert my color grading 2d lookup texture into 3d LUT. When I simply use:

ColorAtlas.GetData(data);
ColorAtlas3D.SetData(data);

I get this:

I tried building my 2d atlass horizontally but it did not helped - the data was messed up in a different way.

So my question is how can I influence the order of the data I get from the 2d atlas and how can I properly pass it into my 3d atlas?

Update: I know that I can GetData from a specific Rectangular area and put it into several arrays, but the result is still the same. This is what I tried:

        Color[] data2D = new Color[0];

        for (int i = 0; i < 32; i++)
        {
            Color[] data = new Color[32 * 32];
            GraphicsDevice.SetRenderTarget(null);

            ColorAtlas.GetData(0, new Rectangle(0, i*32, 32, 32), data, 0, data.Length);

            int oldLength = data2D.Length;

            Array.Resize<Color>(ref data2D, oldLength + data.Length);
            Array.Copy(data, 0, data2D, oldLength, data.Length);
        }
        ColorAtlas3D.SetData(data2D);