Viewport DX11 vs. DX9

I am trying to adapt a patch from DX9 to DX11 and that is so far pretty simple.
The problem I run into is that the viewport transform on the DX9 renderer has another format than the viewport on the DX11 renderer.
Is there a simple way so convert the DX9 transform to the new DX11 viewport.
From what the viewport node takes as an input it seems like decompose might be a good idea to start out from but I am not sure about that.


Since a ViewPort is just a rectangle (no rotation), simple 2d coordinates will do just as good to set it.

If you had modules that set a viewport transform they should be easy to adapt to set a ViewPort object instead.