Action8

Introduction

Define GRFID, Name and Description

There are many new graphic sets available to TTD players. Of course, we need to make sure that we never get sets mixed up. To make sure this will never happen you can set an ID. Another useful feature of Action 8 is the ability to include useful information into the final .grf file. Here, we explain how Action 8 works.

Syntax

Like all other pseudo-sprites, Action 8 consists of hexadecimal bits. There is no limitation in the total amount of hexadecimal bits you can use in Action 8. One term does have a limit though. Let's give an example of what an Action 8 line looks like:

<sprite-number> * <length> 08 <version> <grf-id> <name> <description>

Here is a short overview of what every term means:

Element	Size	Description
<sprite-number>	dec	A sequential sprite number
<length>	dec	The total number of bytes in the action
08	B	Action 08
<version>	B	GRF version
<grf-id>	4*B	A unique ID for your .grf file
<name>	S	A short text containing the name of this set
<description>	S	A longer description of this set

Descriptions

Sprite-number

The number of this sprite.

Action 8 has to be one of the first pseudosprites in the .NFO file. It is however valid to have other actions before it, except those that define new sprites or vehicle (etc.) properties.

Actions 6, 7, 9, B, C, D (except resource management sprites), 10 and 14 are valid before an action 8.

Length

The total number of bytes in Action 8.

GRF Version

This should be the graphics version that your file is written for. This is the version of the GRF format, not the version of your GRF! It is also not the "NFO version" you put at the top of ".nfo" files to announce the used syntax for GRFCodec.

Valid values are:

Value	Compatibility	TTDPatch version	OpenTTD support
07	02..07	2.5 beta 1 or higher	yes
06	02..06	2.0.1 alpha 13 or higher	yes
05	02..05	2.0r1 Stable TTDPatch + TTDPatch 2.0.1 alphas up to 12	yes
04	02..04	2.0 Stable TTDPatch	yes
01	00..01	1.9.1 alpha 28 or higher	no
00	00	1.9.1 alphas up to 27	no

Entries for 00 and 01 are included only for completeness, and to aid with updating existing graphics. They should not be used with new graphics, because they will be incompatible with current TTDPatch and OpenTTD versions. OpenTTD 1.1.0 and later will disable NewGRFs with non-supported GRF versions.

Make sure to set a version number no lower than the minimum version that supports all features which are used by your file.

The compatibility column means how low a version number is supported by the given TTDPatch version, e.g. TTDPatch 2.0r1 supports graphics files with any version from 02 to 05, but not for example 01 or 06.

Version 07 introduces a few minor semantic changes to some graphics features, i.e. the file will behave slightly differently depending on whether it's declared as version 06 or 07. These changes are described in more detail in the pages for the features they affect.

GRFID

This is a series of 4 bytes. It's a convention to use the first two bytes for the creator's initials in ASCII code, e.g. 54 57 for "TW". The last two bytes should be numbers, typically the first number identifying which of the author's sets this is, and the second number being a version number.

In principle, you are free what to use for the GRFID as long as you are sure it is unique, but generally it is best to follow the above guidelines.

Note that GRFIDs starting with FF (i.e. the first byte is FF, such as in FF123456) are reserved for internal purposes and should not be used by regular .grf files. A GRFID of FFFFFFFF is a special case for a .grf file that is always active and cannot be deactivated, used for TTDPatch's feature-specific graphics such as electrified railways or pre-signals.

The extra newgrf file, part of OpenTTD base sets, have to have a GRFID starting with FF "OT". The fourth letter may not be "W" nor "D" which are reserved for the openttd[w||d].grf file. OpenGFX defines 01 for its extra newgrf.

GRFID	purposes
00 00 00 00	n/a
00 00 00 01 .. FE FF FF FF	normal NewGRFs
FF 00 00 00 .. FF FF FF FE	reserved
FF "OT" 00 .. FF "OT" FF	extra base grfs:
FF "OT" 01	OpenGFX
FF "OTD"	TTD base set: openttd.grf
FF "OTW"	TTD base set: openttdw.grf (OpenTTD < 1.1.0)

Name

This short field should contain the name of the set. See GRFActionsDetailed for instructions to generate the necessary byte codes, and for restrictions on what characters you may use. The name must be short because it should fit on one line of the GRF Status window.

Description

This is a longer description of the set. Typically it contains the name of the author and a copyright notice or other attribution. See GRFActionsDetailed for instructions to generate the necessary byte codes, and for restrictions on what characters you may use. The description may be quite long, but should be short enough to fit in the description part of the GRF Status window, or a part of it may be cut off.

Example

Below is an example of what a real Action 8 pseudo-sprite could look like.

1 * 43 08 07 "TW" 01 06 "Tutorial Example" 00 "Changes nothing. Author: A kind person" 00

Let's clarify it bit by bit. In order to understand what the bits say you could use a hexadecimal editor.

Byte	Meaning
1	<sprite-number>
43	<length> of the action in bytes; start counting at 08 (<action>)
08	<action>: sets this pseudo-sprite to function as action 8
07	<version>: GRF format version 7 (this is the version of the used GRF format, not of your GRF)
54 57 01 06	<-grf-id>: ASCII code for TW, then the numbers 1 and 6 to indicate version 6 of TW's first set
"Tutorial..." 00	<name>: Name of the NewGRF
"Changes..." 00	<description>: Description of the NewGRF