20–32 overlapping scrolling layers per scrolling plane

[Kirk_Johnston]

"20–32 overlapping scrolling layers per scrolling plane" - from the Genesis specs on segaretro.   Can someone explain to me what that actually means?   I don't think it's talking about switching priorities because you'd really have to use the other layer too in order to see the overlapping effect using layer priorities, much like the way the clouds are done in the Strite level in Thunder Force IV, so I'm not clear what that description above is talking about specifically.   Are there any examples of Genesis games actually doing this that I can check out?

Edited July 27, 2022 by Kirk_Johnston

[Chilly Willy]

I'd guess they're talking about the fact that the priority is set on a tile basis. The name tables for each plane use a word for each entry, and those entries have the h/v flip, the palette number. the tile number, and the priority. So on a single line, each tile can be set in front or behind the other layer/sprites, depending on the priorities of the tiles in the other plane, and the sprite priorities.

 

[Kirk_Johnston]

1 hour ago, Chilly Willy said:

I'd guess they're talking about the fact that the priority is set on a tile basis. The name tables for each plane use a word for each entry, and those entries have the h/v flip, the palette number. the tile number, and the priority. So on a single line, each tile can be set in front or behind the other layer/sprites, depending on the priorities of the tiles in the other plane, and the sprite priorities.

 

OK, yeah, so it actually is referring to what they're doing with the likes of the overlapping clouds in the Strite level in Thunder Force IV and Mickey going behind the tree in Castle of Illusion as seen here: https://rasterscroll.com/mdgraphics/graphical-effects/row-column-scrolling/

 

It's a very strange way of describing it that the segaretro article used imo. I'd be more inclined to just separate the two things and say you can set the background priority on a per-tile basis as well as the sprite priority to allow different elements to be in front of or behind others, and you can do row/column/line scrolling as another feature, with the ability to combine them both together for some cool visual effects. Maybe not as concise, but a lot easier to understand what it all actually means and does.

 

For a second, I thought they were saying you could actually overlap parts of a single plane visibly on top other parts of the same plane, creating the effect of 20-32 overlapping [scrolling] layers, just like how those clouds in the Strite level in Thunder Force IV are done using both of the available planes together plus switching priorities and line scrolling, but as if this could all be done with a single plane alone, which, as far as I'm aware, is simply not possible. 

 

Glad I've got that a bit more clear now though.

Edited July 28, 2022 by Kirk_Johnston

[Chilly Willy]

Yeah, I think you have it now. And that was weird the way they worded it. Probably because they didn't completely understand it themselves.