[Ohrrpgce] Desiderata for 16-bit Tilemaps

[Ralph Versteegen]

We want to move to (at least) 16 bits per tile, to enable larger tilesets.
This will also allow and require the tile animation system to be upgraded as
well, so the question is how should we make use of 16 bits of tile space?

(Features like parallax and using backdrops as map layers are
separate from this question, though involve replacing other parts of the map
file format. Non-20x20 tiles is also completely separate.)

We could even support using multiple tilesets per map layer, though you
would
have to specify which ones you want. But after originally being keen on that
years ago, it now sounds like too much complexity.

I'm not a fan of the animation ranges of the tile animation patterns. It's
very wasteful, since only a few of those tiles are likely to be animated,
while the rest are garbage, and when you try to use the tile picker to pick
an animated tile, you have a lot of painful to look at garbage animated
tiles
to ignore.  The wastefulness is also the reason that we're limited to just 2
patterns and 160 tiles.

Instead, I propose using an extra layer of indirection between tile IDs and
animation patterns, in the form of a palette of animated tiles.  Tile
animation patterns would be the same, except that you will no longer define
a
range for them. Instead, each pattern can be applied to any tile, and there
no longer needs to be a limit on number of patterns.

You could say which tiles in the tileset can be animated with which pattern,
and those animated tiles get added as *additional* tiles to the tileset.
These could be shown in the tileset editor right below the static tiles Then
in the map editor you can pick those animated tiles direct from the tileset,
or continue to press 1, 2, 3, etc. to turn a tile into the animated version.
If you try to turn a tile into an animated one but it's not yet in the
tileset, you could be prompted to add it. It should also be possible to
delete an animated tile, leading to unallocated gaps.

(This leads to some questions: in case you want to swap tilesets, should you
be able to reorder, copy, and delete animated tiles, so that you can cause
their ID numbers to be the same in different tilesets? Should unallocated
animated tiles be shown, so that you can copy into them? Should writeblock
be
allowed to write unallocated tile IDs?)

We could also reserve some space for future use. I don't know yet what that
might be... multiple tilesets per layer? visual filters?

I'm thinking something like:
0-8191 : regular tiles (max tileset size)
8192-16383 : animated tiles
16384-65535 : unallocated
And a lookup table of 8192 animated tiles, with tile ID and pattern ID for
each.
(8192 should be enough for anybody.... right?)

Also, for consistency we might as well upgrade passmaps and foemaps to 16bit
at the same time. Making use of the extra wall bits for angled or partial
walls
is a much more difficult question.
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