/vr/ - Retro Games

>>2716130
There is one seemingly simple thing that Mode 7 can not do: You can not "roll" the view, like a banked horizon, or a wall (pic related). The reason for this is obvious, once you understand the scanline based zoom.
If you zoom per scanline, then each horizontal line on the screen needs to have a constant distance from the viewer, across its whole length. For a wall though, that's just not the case. The pic makes this easy to see. The wall is closests on the left, the most distant on the right. It would have to change zoom factor per "pixel column", but there's nothing to hook into to do that. A banked view is technically between a wall and a floor.
For a polygon it makes no difference if it's a floor or a wall, it's all the same matrix math. For Mode 7 though, one is trivial, the other impossible. That should show a bit better how Mode 7 not at all polygonal in nature.