I did
mention it once as far as the SNES goes, but it's never been considered in SGDK2. It's possible, of course, yes. That's not the real question, though. How is the question. Modifying the drawing section of the main loop to use two different drawing sprites might work, Have one layer draw on the 3D layer, and everything else on the front 2D layer. Then rotate the sprite for the 3D layer on the X axis slightly so that it tilts back and you have a 3D perspective ala Super Nintendo's Final Fantasy airships or Mario Kart race tracks. You would also need to cover up the sky with something in the distance on the 2D layer, because you're no longer filling up the entire screen with the background. It would also require changing the inner draw loop of the layer, because you're not drawing a rectangular piece of the layer anymore. Instead, you're drawing a trapezoid. Despite all that, this is the simplest method I can think of. A method of implementing Mode 7 generically to use all of Mode 7's features would be more difficult. Everything here would involve a lot of C# knowledge.
But there's really no need to do it like Mode 7 so closely. Mode 7 was invented as a method of fake 3D constrained by the limits of the system. SGDK2 runs on DirectX 9. You could make
real 3D backgrounds instead.
