TECHNICAL INFORMATION ABOUT MAPS:

This documented is intended to convey technical information on how
crossfire deals with the map objects and objects placed on the maps.  For
the most part, I only intend document how the new code works, and not
go too much into history on the older methods.  A lot of the map
code was re-written in early July 2001, which changed how many things are
dealt with.

Mark Wedel
July 7, 2001

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THE MAP HEADER:

The map header is the section at the start of the map file that
describes the maps characteristics.  The values are described below.

The map variables now make some sense, and are only stored in the
map structure itself.  I still include the old value (the 'was') so
if you are looking at old maps, you know what they mean.  Generally
speaking, the values in the map files themselves match the same element
name in the map structure.

'width','height', was 'x','y': Size of the map.

'enter_x', 'enter_y', was ('hp','sp') = (x,y) of the destination on the
	new map.  These are only used if the exit does not have a specific
	location set.

'reset_timeout', was 'weight': stores the number of seconds that need
   to elapse before this map will be reset.  Ie, if 1800, it means this
   map expires after 30 minutes.  This value is not modified once loaded -
   instead reset_time is used to track this.  The value 0 means to use
   a default timeout (MAP_DEFAULTRESET).

'swap_time', was 'value': This controls how many ticks must elapse
    after the map has not been used before it gets swapped out.
    swapping out is different than reset, as a swapped out map will
    get loaded back into memory if someone re-visits it before it is due to
    reset.

'difficulty', was 'level' stores the map difficulty.  If not set to 
    anything, the server code will try to come up with some difficulty value.

'fixed_resettime', was 'stand_still': If nonzero, the map reset time will not
	be updated when someone enters/exits the map.  Thus, once the map has
	been loaded, it will reset in 'reset time' no matter what access
	happen.  This is useful for shops and towns, which are constantly
	accessed, but should be reset periodically.

'darkness', was 'invisible'.  Light/darnkess of map (overall).  If 0,
	all of map is fully bright.  

'unique' - if set, this entire map is unique.  Exactly unique to what
	will depend on how it was created (it could be a per player
	unique map, or maybe a common map that is just permanent for
	all the players.

'nosmooth' - if set, no faces in this map will be smoothed.

'outdoor' - if set, this is a hint that this is an outdoor map.
	If this is not set, weather and dawn/dusk will not occur on this
	map.  It is highly advised that this be set appropriately.

tile_path_<x> - Used with map tiling.  <x> is a number, 1 is north,
	2 is east, 3 south, 4 west.  This determines what map is tiled
	in that direction.  See the section below for more information about
	map tiling.

'shopitems', 'shopgreed', 'shoprace', 'shopmin', 'shopmax' - the type of thing 
	the shop trades in, see doc/Developers/shops for more details

'temp'  - The base temperature in farenhiet for this map.  The temperature
	is modified by the season and weather conditions.  In a map without
	weather effects, this temperature will be used as the static
	temperature for the entire map.  This can be useful to make an ice
	cave actually cold.

'pressure' - This should really never be set on a map.  The pressure in
	millibars.

'humid' - Again, should rarely be set on a map.  The humidity in percent.

'windspeed' - Rarely set.  The windspeed in kph/h.

'winddir' - Rarely set.  Direction of wind, 1-8, 1 is north, clockwise.

'sky' - The sky conditions for this map.  See weather.h.  Don't set this
	unless you really know what you are doing.

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THE MAP OBJECTS:

The objects within the map are saved in standard 'object save' form
(same as is used for the players objects).  Other files document the
actual meaning, but the general form is:

arch <some name>
x <some value>
y <some value>
<other object specific values>
end

Note that x and y are in fact optional.  If not present, the values
default to zero.

Multipart objects:

Multipart objects pose a tricky problem, in that they have to
appear together in the map file - this makes proper handling of
layers hard to deal with.

In old map code, all the single spaces objects were saved, and
then all the multi part objects were saved.  This effectively
means that the multi part objects always ended up on top.  The multipart
objects were saved with all their parts.  For example:

slaying shops/magicshop
hp 14
sp 14
x 1
y 13
end
More
arch store_magic_2
name Magic Shop
slaying shops/magicshop
hp 14
sp 14
x 2
y 13
end
<snip - there are really two more parts>

This method does not work very well with the map tiling however (how do you
reasonably deal with a monster that may be straddling the two maps?)  Current
code now only saves the head of the object.  When the map is loaded, the
objects on the map are examined to see what objects need to have more objects
added on.  Additional parts linked in are put just above floor level when
linked in, so things like shops won't hide items that someone drops on them.
For monsters, this linking shouldn't be a problem - once they start moving,
they will get relinked as normal (on top).

The effect of saving only the head does have the effect of not being
able to customize the non head parts of the object.  This generally should not
be a problem (in the case of shops/building, the exit code now knows to look
only at the head for valid information).  The case where this may not work as
well as expected is for buildings where setting the no_pass to non
archetype defaults will get lost.

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Map Tiling:

Map tiling is a feature that lets multiple maps be connected, effectively
forming a much larger single map.  This is most useful for the outdoor
world maps, where it is not practical to have on massive map, but
the old style tiling method (copying areas of the adjoining map to the next
one) are not very efficient.

The transfer of objects from one map to another tiled map are automatic.
Presuming the proper macros are used (out_of_map, get_map_..), minimal extra
work is necessary for everything to work right 

Notes:
Tiled maps must be the same width/height along the side they are tiled with.
If map1 has a height of 15, and you want to tile along one of the sides, the
map(s) it gets tiled with along that side should also be 15.  Given
the following diagram (not to scale):


+---x1----+----x2---+
|         |         |
| map1    |  map2   y2
y1        |         |
|         |         |
+---------+---------+

x1 is the width of map1, y1 is its height.
x2 is the width of map2, y2 is its height.
map1 will tile map2 as indicated in the above diagram.

 Given that, the following must be true:
y1 must equal y2
x1 must be greater than 12
x2 must be greater than 12
x1 and x2 do not need to be equal

The value is derived as being half the maximum viewable area.  The reason
for this is that the line of sight code (and likely some other code) will only
look one map away from a source coordinate.  While the values can be less
than 12, they should be at least 12 if the map tiles with another one in
that direction.  If the map is an 'end' map (ie, no further tiling in a 
specific direction), then having a value less than 12 should work just fine.

Note that tiles maps do not have to be symmetric - several maps
could tile to a common map.  That common map can only tile back to one of
those.  And example of where this might be used is for a courtyard of
a multi floor house - that courtyard should be visible (and be the same)
from all the levels, but you can only go from the courtyard to first floor
rooms off the courtyard.  This may not be ideal (ie, if flying, you should
be able to go to any floor), but this tiling for elevation is just an
example that can be used.