Hi Marco, unfortunately unlike what you would probably naturally expect, transparency is not something that is automatically provided by low level APIs like Direct3D or OpenGL. It has to be handled by the application drawing polygons in depth sorted order. This has to be done pretty carefully so as not to slow down performance too much. I would like to look into doing it but it doesn't really have anything to do with D3D9 vs D3D11 vs D3D12.

- Michael