Action3

Action 3

Associate feature IDs with graphics sets.

Introduction

Action 3 assigns graphics sets (referenced to by (chains of) action 2(s) to feature IDs (vehicles, stations, houses, industries, ...).

Format

The format of the data is feature-dependent.

The data is:

 <Sprite-number> * <Length> 03 <feature> <n-id> <ids...> <num-cid> (<cargo-type> <set-ID>)... <default set-ID>

Element	Size	Description
<Sprite-number>	dec	A sequential sprite number
<length>	dec	The total number of bytes used in this action
03	B	Defines action 03
<feature>	B	What type of feature the IDs refer to
<n-id>	B	Number of IDs this action 3 associates graphics with
<ids...>	B/B*	IDs of the current feature this action 3 associates graphics with. There must be as many IDs as <n-id> specifies
<num-cid>	B	Number of different cargo types to support
<cargo-type>	B	Cargo type for which to use the following set-ID
<set-ID>	W	Set-ID (from action 2 or from a varaction2 chain) to use for this cargo type
<default set-ID>	W	Default set-ID to use if none of the above matches

Filling in the terms

Sprite-number

This is just the number you are at.

Length

Count the number of bytes in this action.

Feature

This sets the type of feature that you wish to change. Set it to:

00 for trains

01 for road vehicles

02 for ships

03 for planes

04 for stations

05 for canals/rivers

07 for houses

09 for industry tiles

0A for industries

0B for cargos

0F for Objects

10 for Railtypes

n-id

How many items of the current feature this action 3 defines new graphics for. If this is more than one, all items listed will get the same graphics. If this value has bit 7 set (i.e. 80 added), it is a wagon override. See Action 3 - Livery Override for more info on this feature.

You can make a definition with n-id equal to zero (and thus no ids that follow).  This creates a generic feature-specific definition not associated with any particular feature.  At the moment, this is used for generic callbacks, but might be extended to other functions eventually.

ids

Feature IDs to use this action 3 for. All IDs are counted from the first of their class, i.e. the first road vehicle has 00, as does the first plane, the first ship, and the first train vehicle.

In OpenTTD since r13482, each ID is an extended byte for vehicles, otherwise the ID is a regular byte.

For feature 05 (canals/rivers):

ID	Description	Number of sprites
00	Watercliffs	4*
01	Locks	24
02	Dikes	12
03	Icons	1*
04	Flat docks	4
05	River slopes	4*
06	River watersides	12*5 (last 4 for slopes)
07	River GUI	2

Note: The Number of sprites for feature 05 canals/rivers may change via a graphics flag set in Action0Canals

For town buildings, the IDs are the house IDs, and specifying a house ID that haven't been defined before (by setting its property 08) doesn't do anything, but doesn't cause an error, either. Note that you don't necessarily have to assign a set-ID to a house ID, the old TTD sprite of the substitute type will be used if you don't do so.  Industry tile IDs work in the same manner.

num-cid

Number of cargo type definitions that follow. Can be zero if only the default follows.

For features 05 (canals/rivers), 07 (houses), 09 (industry tiles), 0A (industries), and 0B (cargoes) this must always be zero.

cargo-type

For vehicles (features 00 .. 03) and stations (feature 04)

The cargo-type for which the set-ID applies.  If the item is built to use this type of cargo, or if it is refitted for it, the given set-ID is used as its graphics.  See column "type A" in the table at CargoTypes for a list of cargo-type values.

If the grf file has installed a cargo translation table, the cargo type here refers to the cargo with the label in the given slot of the translation table, e.g. if you use cargo-type=08, it refers to the cargo that has the label in the ninth slot (numbered 08) in the translation table.

If defined, cargo-type FF is used for graphics shown in the purchase or construction window.

For stations, you can additionally define a special cargo-type of FE which prevents the default from being used (which would show the sum of all cargo).  Instead, the given set-ID is displayed with no cargo at all.

For railtypes (feature 10)

Railtypes are available only in OpenTTD > r19056 and its action 3 re-uses the 'cargo'-type definition in order to assign the type of graphics defined by the associated set-ID:

'Cargo' Type	Sprite Type	#Sprites	Useage
00	Icons and cursors(a)	16	4 rail directions, autorail, depot, tunnel and convert rail. First all icons, then all cursors.
01	Track overlays for junctions and PBS(a)	10	6 flat and 4 slope pieces. Sprites should contain only the track, with no landscape.
02	Underlay(a)	16	6 flat and 4 slope, and 1 X crossing pieces with track, and 5 junction pieces without track. Sprites should contain the track and the 'ballast' below it. No landscape should be drawn.
03	Tunnel(a)	4	1 sprite for each direction. Sprite is overlay for track in existing tunnel graphics. The original ground sprite is drawn, then the overlay, then possibly a train and the original tunnel head is drawn over the top. This keeps compatibility with different landscape types. Sprite order: SW, NW, NE, SE.
04	Catenary wire	28	Follows the same layout for wires of the first 28 sprites as Action5 type 5.
05	Catenary pylons	8	Follows the same layout for pylons of the 8 sprites after the wires as Action5 type 5.
06	Bridge surfaces(a)	6	10 sprites if we ever include diagonal bridges.
07	Level crossing overlay(a)	10	1 rail overlay and 4 light sprites for X and Y.(b)
08	Depots	6	2 sprites for each southish, 1 sprite for each northish. Follows the original layout for depot sprites.(c)
09	Fences	8	X, Y, Vertical, Horizontal, SW slope, SE slope, NE slope and NW slope. Follows the same layout as original original fence sprites at sprite 1301.

(a) These sprites must be provided, the others may be left out, if not needed.

(b) Level crossing sprites:

Sprite number for X	Sprite number for Y	Useage
0	1	Rail overlay
2	3	North light
4	5	East light
6	7	West light
8	9	South light

(c)Depot sprites:

Sprite Number	Useage
0	NE wall for SE-entry depot.
1	Depot building for SE-entry depot.
2	NW wall for SW-entry depot.
3	Depot building for SW-entry depot.
4	Depot building for NE-entry depot.
5	Depot building for NW-entry depot.

For canals/rivers, houses, industry tiles, industries and cargoes (features 05, 07, 09, 0A and 0B)

As <num-cid> is zero for features 05 (canals/rivers), 07 (houses), 09 (industry tiles), 0A (industries), and 0B (cargoes), <cargo-type> and <set-ID> need to be skipped and you only have to set <default set-ID>.

For objects (feature 0F)

Objects support a buy menu sprite similar to vehicles (cargo-type FF).

default set-ID

Default set-ID if no entry from the cargo-type list above matches, or if there are no special cargo-types listed at all.

Example

Below is an example of what a real action 3 pseudo-sprite could look like for a train engine.

 13 * 7   03 00 01 02 00 00 00

Byte	Meaning
13	<sprite-number>
7	<length> of the action in bytes; start counting at 03 (<action>)
03	<action>: sets this pseudo-sprite to function as action 3
00	<feature>: 00 for trains
01	<n-id>: One ID to change in this case
02	<ids...>: vehicle ID (02 - Ploddyphut Choo-Choo)
00	<num-cid>: this engine doesn't have cargo-specific graphics
00 00	<default set-ID>: Use action 2 ID 00, because it is a word value you add 00