Espozo wrote:
So is it kind of like this?
http://www.system16.com/hardware.php?id=747System 16 wrote:
1 = Top 8 pens appear over sprites (split tilemap)
Hey, you know, I just thought of something... If you had a 256 color BG that was behind sprites but above a 4 color BG that was above the sprites, couldn't you make it to where it looked like you had 2 256 color BGs that are not moving? This could be good for an RPG. If you wanted a little area for overlapping stuff, like just the railings on a staircase, but still wanted a free BG layer, you could do the same with sprites.
There's no such thing as "a BG that's above another BG but behind sprites" on the SNES. The priorities of the BGs and the four sprite priority codes are fixed for each mode, and they are always transitive.
It is possible to use sprites to mask other sprites, since sprite-sprite priority is independent of layer priority. Chrono Trigger does this for the scene where Lavos emerges from the earth--actually, I suspect it's a fairly common technique.
Quote:
If the information for each pixel gets cut in half, I wonder if all the BG Modes on SNES were originally supposed to use the Mode 7 format... (What are the different graphics formats on the SNES? I know one of them is called planar, and it's difficult to do 3D stuff on it because the bits for each pixel are spread out. Are they in a line together in Mode 7? Why was the SNES even designed to use planar over something else? Was it cheaper?)
The SNES planar tile format allows different color depths of tiles to be decoded by the same hardware logic. A 4bpp tile is just two 2bpp tiles one after the other, and an 8bpp tile is four 2bpp tiles. If the formats were different (e.g. packed pixel, or fully interleaved bitplanes) the PPU would need separate logic to decode each type.
Mode 7 is packed pixel because it has to be to support random access, which you need for rotation. You can't fetch just one pixel from a bitplane, you have to fetch 8 sequential pixels at once.