I guess I have an idea to do multi-directionnal scrolling wihtout any glitches horizontally nor vertically, without using 4-screen mirroring and without wasting any CPU time during the frame (no raster effects).
However that requires mapper 118 (TLSROM or anything close to it), or mapper 5 (EXRAM not needed) or any mapper that can allow mapping of name tables individually.
Instead of doing the traditionnal "vertical" or "horizontal" screen arrangement, do a "chessboard" arrangement of them. So that screens are arranged as 0, 1, 1, 0.
Or in other words CIRAM A10 = PPUA10 COR PPUA11.
That way data can be drawn on the right of the screen without being imediately seen at the left (and vice-versa), and the same applies for top bottom. This works in theory when scrolling to any direction, but I don't know how well it works for scrolling diagonally (I guess it would have glitches in the border too). This could still be good for any game that scroll in 4 way but only 1 direction at the same time (RPGs for instance, using TKSROM this could be great).
However that requires mapper 118 (TLSROM or anything close to it), or mapper 5 (EXRAM not needed) or any mapper that can allow mapping of name tables individually.
Instead of doing the traditionnal "vertical" or "horizontal" screen arrangement, do a "chessboard" arrangement of them. So that screens are arranged as 0, 1, 1, 0.
Or in other words CIRAM A10 = PPUA10 COR PPUA11.
That way data can be drawn on the right of the screen without being imediately seen at the left (and vice-versa), and the same applies for top bottom. This works in theory when scrolling to any direction, but I don't know how well it works for scrolling diagonally (I guess it would have glitches in the border too). This could still be good for any game that scroll in 4 way but only 1 direction at the same time (RPGs for instance, using TKSROM this could be great).