Action0/Airport Tiles

Introduction

Defining properties of airport tiles

This feature is available as of OpenTTD > r19204

Airport tiles work like industry tiles and similarly to town buildings, except that they are not stand-alone. This means an airport tile can't stand alone, it's always part of an airport.

Properties

Number	Version	Size	Description
08		B	Substitute airport tile type
09		B	Airport tile override
0E		B	Callback flags
0F		W	Animation information
10		B	Animation speed.
11		B	Animation triggers

Descriptions

Substitute tile type (08)

This tile type will be used instead of your new one if your definition isn't available for any reason. Assigning this property copies the properties of the old type just like it does with houses. If this tile's action 3 appears before this property is set, the action 3 will have no effect.

Airport tile override (09)

Works like the house override property for houses and industry tiles.

Callback flags (0E)

Bit	value	meaning
0	1	use callback 153 to decide the next animation frame
1	2	use callback 154 to decide animation speed
2	4	(reserved)
3	8	(reserved)
4	10	use callback xx to check if a slope is suitable (not yet implemented)
5	20	use callback 150 to decide if default foundations need to be drawn
6	40	use callback xx to allow or deny autosloping below the tile (not yet implemented)

Please note that callback 152 doesn't have a bit here. To use callback 152, simply set the wanted bits in property 11 and it will work as intended.

Animation information (0F)

The low byte specifies the number of animation frames minus one, so 00 means 1 frame, 01 means 2 frames etc. The maximum number of frames is 256, although you can have some problems if your animation exceeds FD (253) frames. The high byte must be 0 for non-looping animations and 01 for looping animations. Every other value is reserved for future use. In addition, if the whole word contains FFFF, animation is turned off for this tile (this is the default value).

Animation speed (10)

The meaning is the same as for house property 1B, but the lower limit is 0 instead of 2, so the fastest possible animation changes frames every game tick (27ms). The default value is 2.

Animation triggers via callback 153 (11)

This shares some flags with industry tiles and others with stations. Call callback 153 when:

Bit	Value	Meaning
0	1	airport was just constructed
1	2	the tile is processed in the periodic processing loop
2	4	new cargo arrives at the station (for all airport tiles the same)
3	8	a cargo type gets removed from the station (for all airport tiles the same)
4	10	every 250 ticks (for all airport tiles the same)