Action8

Define GRF ID, Name and Description

Action 8

Define GRF ID, Name and Description

-=Why does your .grf file need an ID?=-

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.

-=Format=-

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|Graphics 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||

-=Filling in the terms=-

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.

Version

This should be the graphics version that your file will support. Valid values are:

||TTDPatch version|Value|Compatibility

2.5 beta 1 or higher|07|02..07

2.0.1 alpha 13 or higher|06|02..06

2.0r1 Stable TTDPatch + 2.0.1 alphas up to 12|05|02..05

2.0 Stable TTDPatch|04|02..04

1.9.1 alpha 28 or higher|01|00..01

1.9.1 alphas up to 27|00|00||

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 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. 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.

GRF ID

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 GRF ID as long as you are sure it is unique, but generally it is best to follow the above guidelines.

Note that GRF IDs 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 GRF ID of FFFFFFFF is a special case for a .grf file that is always active and cannot be deactivated, used for feature-specific patch graphics such as electrified railways or pre-signals. This kind of file is shown with a blue flag in the GRF Status Window.

The extra newgrf file, part of OpenTTD base sets, have to have a GRF ID 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.

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 05 54 57 01 06 20 54 75 74 6F 72 69 61 6C 20 65 78 61 6D 70 6C 65 00 20 43 6F 70 79 72 69 67 68 74 3A 20 53 79 73 74 65 6D 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

05|<version>: this .grf file works with TTDPatch 2.0r1 + alpha series

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

20 54 .. 65 00|<name>: Tutorial example

20 43 .. 6D 00|<description>: Copyright: System||