Provided by: sopwith_2.7.0-1_amd64 
NAME
.sop - Sopwith mission format
DESCRIPTION
The Sopwith mission format allows sopwith(6) to load custom user-defined levels and other
modifications to the game. The files use Yocton as their basic format:
⟨https://github.com/fragglet/yocton⟩
Each .sop file can contain three different sections:
level This section contains level data. If present, the game's level is replaced with an
entirely new level defined within this section. See LEVEL SECTION below.
symbols
This section allows the game's symbols (sprites) to be replaced. This allows
graphical modifications to the game. See SYMBOLS SECTION below.
sounds This section allows the game's music to be replaced. See SOUNDS SECTION below.
LEVEL SECTION
The level section allows a complete new level to be defined. At present only a single
level can be defined, although this may change in the future. Each level contains two
types of subsection: ground, which defines the level's terrain, and multiple object
sections, each of which defines an in-game object.
The ground subsection is a list of decimal integer values that describe the level's
terrain. Each value is defined through a Yocton property named _. Values should be in the
range 16-199, and there should be a minimum of 320 (ie. one screen's worth). The following
is an example:
ground {
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
...
}
Each object subsection defines an object that appears in the level. The following is an
example:
object {
type: PLANE
x: 30
orient: 0
territory_l: 0
territory_r: 0
faction: PLAYER1
}
As seen, each object has a number of different properties:
type See OBJECT TYPES below.
x The X coordinate within the level where the object appears. The Y coordinate is set
automatically depending on the object type and can not be specified.
orient For planes, defines the direction in which planes face: 0 (right) or 1 (left). For
ground targets, this controls the type of ground target; see TARGET TYPES below.
faction
Specifies the faction to which the object belongs. See FACTIONS below.
transform
For ground targets, this specifies a "transformation" to apply to the symbol.
Eight different transformations are supported: 0 (no transformation); 1 (rotate 90
degrees counterclockwise); 2 (rotate upside-down); 3 (rotate 90 degrees clockwise);
4 (flip vertically); 5 (mirror, then rotate 90 degrees counterclockwise); 6
(mirror); 7 (mirror and then rotate 90 degrees clockwise). If you want to see an
Ox do a headstand, this is the property to use, although it's more likely you'll
want to use it to make tanks face the right direction.
territory_l
For planes, the left boundary of the range of the level the plane defends.
territory_r
For planes, the right boundary of the range of the level the plane defends.
The following is an example of a minimal level section that just contains a flat ground
with no objects other than the player's plane:
level {
object {
type: PLANE
x: 30
orient: 0
territory_l: 0
territory_r: 0
faction: PLAYER1
}
ground {
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
_: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64 _: 64
}
}
OBJECT TYPES
The following object types can appear in a level:
PLANE Defines either a player or computer-controlled plane. The faction property controls
whether it is a human player or computer-controlled player; see FACTIONS below.
Computer-controlled planes will defend their "territory", the range of which is
defined by the territory_l and territory_r properties. If the player enters this
territory, they will take off from their base and attack.
TARGET A ground target. The value of the orient property defines the type of target, see
TARGET TYPES below. The value of the faction property specifies the faction to
which the target belongs. When one player destroys all targets owned by all enemy
factions, the game advances to the next level.
BALLOON
Observation balloon. The value of the orient property defines the type of balloon;
0 = spherical balloon, 1 = Caquot-style. The value of the faction property
specifies the faction to which the balloon belongs.
OX An Ox (type of cattle). The Ox does nothing except act as an obstacle, and does not
need to be killed to advance to the next level. Does not appear in novice mode.
BIRD A single bird flies the randomly around the level. The bird acts as an obstacle
that the player(s) must avoid. Does not appear in novice mode.
FLOCK A flock of birds moves along the top of the screen. The flock acts an obstacle and
may disperse into many different birds if disturbed. Does not appear in novice
mode.
FACTIONS
Military objects belong to a "faction"; objects allied to a different faction are
considered enemies. The color of the object indicates the faction:
PLAYER1
For planes, cyan fuselage and magenta wings. This corresponds to the human player
in single player mode, and player 1 in multiplayer mode.
PLAYER2
For planes, magenta fuselage and cyan wings. This corresponds to the computer
opponent in single player mode, and player 2 in multiplayer mode.
NONE Used for animals / non-military targets.
The following values are also recognized; they are currently (effectively) unused, but may
be used in the future if the multiplayer feature is extended to support more than two
players.
PLAYER3
Maps to PLAYER2 in single player mode, or PLAYER1 in multiplayer mode. Planes of
this faction are currently ignored in multiplayer mode.
PLAYER4
Maps to PLAYER2. Planes of this faction are currently ignored in multiplayer mode.
PLAYER5, PLAYER7
Maps to PLAYER1, but planes with this faction are currently ignored.
PLAYER6, PLAYER8
Maps to PLAYER2, but planes with this faction are currently ignored.
SYMBOLS SECTION
The symbols section allows the game's graphics to be replaced. The section can contain a
number of subsections, one for each type of graphic. Graphics are defined as multiline
text strings. The following is an example of a symbols section that changes the hangar
graphic to add an extra (white) flag:
symbols {
swtrgsym {
0:
" - - \n" &
" - # # # # - * * * * \n" &
" - # # # # - * * * * \n" &
" - - \n" &
" - - \n" &
" - - \n" &
" - - \n" &
"* * * * * * * * * * * * * * * * \n" &
"* * * * * * * * * * * * * * * * \n" &
"* * - - - - - - - - - - - - * * \n" &
"* * - * * * * * * * * * * - * * \n" &
"* * - * * * * * * * * * * - * * \n" &
"* * - * * * * * * * * * * - * * \n" &
"* * - * * * * * * * * * * - * * \n" &
"* * - * * * * * * * * * * - * * \n" &
"* * - * * * * * * * * * * - * * \n"
}
}
Graphics are limited to the original four CGA colors: black (space); cyan (asterisk);
magenta (hyphen) and white (number sign / pound / octothorpe). Cyan and magenta are
swapped for enemy planes (single player) and player 2 (multiplayer).
The following graphics are defined:
swplnsym (16x16)
Plane. There are four frames, for facing right (0), rotated 22.5 degrees
counterclockwise (1), 45 degrees (2) and 67.5 degrees (3).
swhitsym (16x16)
Crashing plane. There are two frames of animation.
swwinsym (16x16)
Plane flying into the distance after completing the level. There are four frames of
animation.
swtrgsym (16x16)
Ground target. Each frame is a different target type and the values are those from
TARGET TYPES below.
swhtrsym (16x16)
Destroyed ground target. Each frame a different target type; the values are those
from TARGET TYPES below. The number of pixels in the symbol control the size of the
explosion when the target is destroyed.
swballoonsym (16x16)
Observation balloon. Each type of balloon has three animation frames: drifting
left, centered, and drifting right. Spherical balloon starts at frame 0 and Caquot-
style balloon begins at frame 3.
swoxsym (16x16)
Ox. There is one frame.
swflksym (16x16)
Bird flock. There are two frames, for the "flapping wings" animation.
swbrdsym (4x2)
Bird. There are two frames, for the "flapping wings" animation.
swbmbsym (8x8)
Falling bomb. There are two frames, for facing right (0) and rotated 45 degrees
counterclockwise (1).
swmscsym (8x8)
Missile. There are four frames, for facing right (0), rotated 22.5 degrees
counterclockwise (1), 45 degrees (2) and 67.5 degrees (3).
swbstsym (8x8)
Starburst (flare). There are two frames of animation.
swexpsym (8x8)
Debris after an explosion. There are eight frames for different types of debris.
swmedalsym (8x12)
Medals. There are three frames for each different type.
swribbonsym (8x2)
Ribbons. There are six frames for each different type.
swshtsym (16x16)
Shot out window. There is a single frame.
swsplsym (32x32)
Bird "splatted" into window. There is a single frame.
TARGET TYPES
0 Hangar
1 Factory
2 fuel tank
3 Tank
4 Truck
5 Tanker truck
6 Flag
7 Tent
8-12 User-defined target; the symbols section should be used to supply the graphics (see
SYMBOLS SECTION above). Type 12 produces a big explosion like an oil tank when
destroyed.
13-17 "Passive" user-defined target (does not fire at enemy planes). Type 17 produces a
big explosion like an oil tank when destroyed.
18 Radio tower
19 Water tower
SOUNDS SECTION
The sounds section allows the in-game music to be replaced. There is only one property at
present, named title_tune; its value is a string containing a sequence of notes to play.
The following is an example of a sounds section that replaces the title music with the
beginning of "Au Clair de la Lune":
sounds {
title_tune:
"g4/r8/g4/r8/g4/r8/a4/r8/b2/r4/a2/r2/" &
"g4/r8/b4/r8/a4/r8/a4/r8/g2/r2/"
}
As seen, the format consists of a number of musical notes (a-g) separated by '/'
characters. The notes are in the C major scale. Each note is followed by a number that
indicates the length of the note as a fraction of a whole note; for example, 2 means half-
note, 4 means quarter-note, etc. The following additional syntax is also supported:
• For a rest, use "r" instead of a note character. The syntax is otherwise identical
to that for a normal note, with the only difference being that no note will be
played.
• To play a sharp, append a '+' character. For example, "g+4/" represents a quarter-
length G#. Alternatively you can append a '-' to play a flat; for example "e-2/" is
a half-length E-flat (aka D#).
• Prefix a note with < or > to shift down or up an octave. All subsequent notes will
be played in this octave.
• Append a '.' character to play a dotted note. A dotted note plays for 50% longer
than a normal note.
The original DOS version of Sopwith interpreted notes as being in the A minor scale, but
this is believed to have been a mistake and notes are now assumed to be in the more common
C major scale. This does, however, mean that tunes from DOS .exe hacks will play
differently; any A or B notes will need to be shifted down one octave to convert to the C
major scale.
SEE ALSO
sopwith(6),
AUTHORS
This manual page was written by Simon Howard.
HISTORY
The original DOS version of Sopwith only supported a single level, although later versions
increased the difficulty by repeatedly playing the same level again at increasing speeds.
Some modifications were made by fans by hex-editing the DOS .exe file.
Some simple hacks just changed the name shown on the title screen (one changed it to "Red
Baron", for example). Some more elaborate mods that changed the level itself included
"Blokwit" and "Sokwith". Andrew Jenner even developed a basic level editor that allowed
people to make their own maps, although the changes that can be made using this technique
are inherently limited.
Full support for custom maps did not appear until 2024, with SDL Sopwith's v2.4 release.
There will likely be further future extensions to this format to allow people to share
more elaborate modifications to the game.
sopwith-mission(5)