ReadingPatchVariables

Introduction

Since 2.0.1 alpha 48, it has been possible to use action D to read various special Patch variables. These are usually switch values, but there are also a few other useful values.

Syntax

<Sprite-number> * <Length> 0D <target> <operation> <variable> FE FF FF 00 00

Element	Size	Description
0D	B	Defines action 0D
<target>	B	Target parameter
<operation>	B	As for ActionD, but only assignment is valid.
<variable>	B	Patch variable number to read. See below.
FE	B	Defines a special variable access
FF FF 00 00	D	Indicates that a patch variable is being read

variable

The following patch variables are defined:

variable	Switch	Value
00	miscmods/-Yo	Bit switch
01	experimentalfeatures/-XF	Bit switch
02	morevehicles/-x	Vehicle array multiplier
03	mountains&curves;/-mc	Two bytes with four sets of two bits
04	planecrashcontrol/-Xc	Bit switch
05	autorenew/-Xa	Signed value
06	multihead/-M	Speed increase, in percent
07	disasters/-XD	Bit switch
08	unifiedmaglev/-XM	Unified maglev mode
09	bridgespeedlimits/-XX	Speed fraction, in percent
0A	---	TTD Language, see the "new scheme" for action 4
0B	startyear/-XY	Year-1920
0C	morebuildoptions/-YB	Bit switch
0D	moresteam/-YM	value=LF (two hex digits), L=length, F=frequency
0E	freighttrains/-Yf	weight factor
0F	wagonspeedlimits/-YL	Speed increase for empty wagons
10	planespeed/-YP	speed factor
11	dual company colors	2CC colormap base sprite (since r1404)
12	miscmods2/-Zm	Bit switch (since r1738)
13	map size information	Format = -MABXYSS (since r11961 and r1817)
		M : the type of map
		bit 0 set : squared map. Clear : rectangular map
		bit 1 set : Y is the bigger edge(bit 0 is clear).Clear : X is the bigger edge.
		A : minimum edge(log2) of the map
		B : maximum edge(log2) of the map
		XY : edges(log2) of each side of the map.
		SS : combination of both X and Y, thus giving the size(log2) of the map
		All map sizes will be substracted by 6, as to keep the size 64 the smallest one, thus zero based

If experimentalfeatures, miscmods, or miscmods2 are off, the corresponding value will be zero. For all other switches, the value is unspecified if the switch is off, so action 7 variable 85 should be checked first.