VariationalAction2/Objects
From GRFSpecs
Introduction
Variables
| Variable | Size | Version | Description |
|---|---|---|---|
| 40 | D |  1.1  2.6 | Relative position, like Industry Tile var43 |
| 41 | W | 1.1 2.6 | Tile information, see below |
| 42 | D | 1.1 2.6 | Construction date from year 0 |
| 43 | B | 1.1 2.6 | Animation counter, see below |
| 44 | B | 1.1 2.6 | Object founder information |
| 45 | D | 1.1 2.6 | Get town zone and Manhattan distance of closest town |
| 46 | D | 1.1 2.6 | Get square of Euclidian distance of closest town |
| 47 | B | 1.1 2.6 | Object colour |
| 48 | B | 1.1 2.6 | Object views |
| 60 | W | 1.1 2.6 | Get object type at offset |
| 61 | B | 1.1 2.6 | Get random bits at offset |
| 62 | D | 1.1 2.6 | Land info of nearby tiles |
| 63 | W | 1.1 2.6 | Animation counter of nearby tile |
| 64 | D | 1.1 2.6 | Count of object, distance of closest instance |
Description
Tile information (41)
The return value has the format of ss0t where t is the terrain type which the tile is on, same values as canal var81.
As of TTDPatch r2088, ss contains the slope data of the tile, same format as for industrytile var60. The meaning of the individual bits is:
| Bit | Meaning |
|---|---|
| 0 | West corner is above the lowest |
| 1 | South corner is above the lowest |
| 2 | East corner is above the lowest |
| 3 | North corner is above the lowest |
| 4 | The tile is a steep slope (*) |
(*) - Steep slopes have this bit plus 3 points raised, giving them values of 0x17, 0x1B, 0x1D and 0x1E.
Animation Counter (43)
This byte gets the actual value of the animation counter (note that action0, property 10, bit 6 must be set for this to work).
Object founder information (44)
This byte contains the ID of the company that funded the object, or 10h if the object was placed in the scenario editor.
Get town zone and Manhattan distance of closest town (45)
Like industry var65 but instead of an offset the current tile is used.
Get square of Euclidian distance of closest town (46)
Like industry var66 but instead of an offset the current tile is used.
Object colour (47)
This byte returns the colour of the object.
(since TTDPatch r2351 and OpenTTD r21259)
Get object views (48)
Returned value stands for a particular view of an object. Number and rank of set-IDs must match the value given in the object's action0 prop17, i.e. for an object with 4 views, prop48 may return values 0 .. 4. Since OpenTTD r21455.
Get object type at offset (60)
The parameter of this variable is an offset from the current tile. The low nibble contains the signed X offset (that is 0h=0, 1h=+1 ... 7h=+7, 8h=-8, 9h=-7 ... Fh=-1), the high nibble contains the Y offset. Therefore the parameter 00h accesses the current tile itself. The high word of the return value is currently reserved, and the low word can be:
- 00xxh if the tile is an object tile and was defined in the current GRF with ID xx.
- FFFEh if the tile is an object tile that was defined in another GRF file or it's a default object.
- FFFFh if the tile isn't an object tile.
Get random bits at offset (61)
Returns the same values as industry var61. The offset it from the current tile and is signed.
To get the random bits from a tile using a offset relative to the north tile of the object, see the example below.
Land info of nearby tiles (62)
Returns the same values as industry tile var60. The offset it from the current tile and is signed.
To get the land info from a tile using a offset relative to the north tile of the object, see the example below.
Animation counter of nearby tile (63)
Returns the var43 of another tile given by the signed offset.
To get the animation counter from a tile using a offset relative to the north tile of the object, see the example below.
Count of object, distance of closest instance (64)
Returns the same values as industry var67. The distance is from the current tile.
Examples
Getting the north tile random bits
The following code uses variable 40, 61 and 7B to read the random bits of the north tile of the object.
0 * 0 02 0F xx 81
40 30 FF // Get relative position of object tile as yx
\2^ 1A 20 77 // Negate the numbers in bits 0..3 and 4..7 ...
\2+ 1A 20 11 // ... (here we can optionally insert another (positive) offset, to get some other tile relative to the north tile)
\2^ 1A 20 88 // ... (we need to split the xor in two parts, so bits 0..3 do not influence bits 4..7)
\2rst 7B 61 00 FF // Get the random bits at the northern tile
...
