Liveries & Graphics

The signature feature of AeroLiners Set is "authentic liveries". This page explains how aircraft graphics and liveries are organized, rendered, and switched.

Core concepts

• Each aircraft (one .pnml file) defines several spritesets, corresponding to different flight states: Flight, Grounded, Climbing, Touchdown, Landing.
• Each livery corresponds to an independent spriteset (e.g. ATR_42_300_AerLingusRegional_Flight), referencing its own independent PNG file.
• Livery switching is implemented via cargo_subtype: the "cargo item" you choose when refitting is actually the livery number, and each livery's name comes from the STR_VLIV_* string defined in cargotable.pnml.

File makeup of a model

Using src/gfx/ATR/ATR42/42-300/ as an example:

42-300/
├── (0)Greyscale.png        # Greyscale base (cargo_subtype 0)
├── AerLingusRegional.png   # Livery 1
├── AirSouthwest.png        # Livery 2
├── AurignyAirServices.png  # Livery 3
├── ...                     # More airline liveries
└── 42-300.pnml             # Aircraft logic

How it works in .pnml (excerpt)

42-300.pnml defines the sprite pickup positions for 8 frames per state with a macro:

#define ATR_42_300_sprite_layout_template(name)        \
spriteset (name##_Flight, IMAGEFILE)                   \
{                                                      \
  [  1, 1, 46, 22, -23, -11, ANIM]                     \
  [ 52, 1, 38, 19, -19, -10, ANIM]                     \
  ...                                                  \
}                                                      \
spriteset (name##_Grounded, IMAGEFILE) { ... }         \
spriteset (name##_Climbing, IMAGEFILE) { ... }         \
spriteset (name##_Touchdown, IMAGEFILE) { ... }        \
spriteset (name##_Landing,  IMAGEFILE) { ... }

Then, for each livery, switch the IMAGEFILE macro and instantiate the template:

#define IMAGEFILE "src/gfx/ATR/ATR42/42-300/(0)Greyscale.png"
purchase_sprite(ATR_42_300, 285, 1, 46, 23, -23, -12)
ATR_42_300_sprite_layout_template(ATR_42_300_Greyscale)
#undef IMAGEFILE

#define IMAGEFILE "src/gfx/ATR/ATR42/42-300/AerLingusRegional.png"
ATR_42_300_sprite_layout_template(ATR_42_300_AerLingusRegional)
#undef IMAGEFILE

State switching is driven by the flight_state() macro (reading vehicle variable 0xE2):

switch (FEAT_AIRCRAFT, SELF, ATR_42_300_Greyscale, flight_state())
{
  15: ATR_42_300_Greyscale_Climbing;
  18: ATR_42_300_Greyscale_Flight;
  21: ATR_42_300_Greyscale_Landing;
  22: ATR_42_300_Greyscale_Touchdown;
      ATR_42_300_Greyscale_Grounded;
}

And "which livery is selected" is decided by cargo_subtype:

switch (FEAT_AIRCRAFT, SELF, ATR_42_300_sprites, cargo_subtype)
{
  1: ATR_42_300_AerLingusRegional;
  2: ATR_42_300_AirSouthwest;
  ...
     ATR_42_300_Greyscale;   // default greyscale
}

How to add a livery

1. Drop a PNG into the model's directory (same dimensions as existing liveries, usually a horizontally-tiled multi-frame sprite sheet).
2. In the .pnml, add a new IMAGEFILE + template instantiation (follow an existing livery).
3. In cargotable.pnml, define a STR_VLIV_* string for the new livery.
4. In the model's .pnml cargo_subtype switch, assign a number to the new livery, and add the corresponding display text and (for freighters) capacity in cargo_subtype_text / cargo_subtype_capacity.
5. In lang/*.lng, provide translations for the new string in every language.

Greyscale

The greyscales/ directory holds each model's greyscale PNG as a base appearance with no airline markings ((0)Greyscale.png). It is cargo_subtype 0 for every model and a common base image when drawing new liveries.

Back: Building from Source → ｜ Next: Translating →