Additions to NewGRF Specifications in JGR's Patchpack in NML

This document describes non-standard additions to the Official OpenTTD NML Specifications which are present in this patchpack and the associated NML fork.

These additions MAY also be present in other patchpacks. They MAY be removed or moved in future, if necessary.

Not all standard NewGRF features are supported by NML, consequently not all non-standard additions to the specifications are supported by this patchpack's associated NML fork, or are listed in this document.
See the associated non-NML document for more details.

All of the non-standard features listed below will automatically emit suitable feature tests, conditionals, etc. such that NewGRFs which use these features will work correctly on OpenTTD versions which do not support these features, including standard trunk OpenTTD and older/other patchpack versions.

All of the non-standard variables listed below will return 0 on OpenTTD versions which do not support these features/variables, including standard trunk OpenTTD and older/other patchpack versions.

Features with separate pages

• Road stops (FEAT_ROADSTOPS)

Builtin functions

extended_feature_test(feature_name[, min_version[, max_version]])

Railtypes properties

Roadtype properties

Tramtype properties

Object properties

Object variables

Variables in the table below which are not supported by the version of OpenTTD being used return a value of 0.

Global variables properties

The variables listed below should set inside an item and property block of the form:

item (FEAT_GLOBALVARS) {
	property {
		...
	}
}

Syntax example:

item (FEAT_GLOBALVARS) {
	property {
		lighthouse_generate_amount: 255;
		transmitter_generate_amount: 0;
		extra_station_name: [string(STR_STATION_NAME1), bitmask(EXTRA_STATION_NAME_FLAG_RAIL)];
		extra_station_name: [string(STR_STATION_NAME2), bitmask(EXTRA_STATION_NAME_FLAG_ROAD, EXTRA_STATION_NAME_FLAG_TOWN_CENTRE_ONLY)];
	}
}
		

Replace new sprites

Signal graphics using switches

This feature allows signal sprites to be specified using switches in a very similar manner to railtype signals in item (FEAT_RAILTYPES) { graphics { signals: ... } } blocks.
However this applies to all signals, not only those of a particular rail type.
Railtype signal graphics have a higher priority than general signal graphics as set here.

Variables: extra_callback_info1, extra_callback_info2, and terrain_type are the same as for railtype signals.

This feature is not supported by standard OpenTTD or by standard NML.
If the use of this feature is not optional, the feature name: action3_signals_custom_signal_sprites should be checked using the extended_feature_test function and if necessary a suitable fallback used or error message shown.

An item (FEAT_SIGNALS, custom_signals, 0) { } block should be used to define properties and graphics.
The graphics block should contain a single default switch.

Custom signal sprites example:

grf {
	...
}

if (!extended_feature_test("action3_signals_custom_signal_sprites")) {
	error(FATAL, string(STR_UNSUPPORTED_VERSION));
}

switch (FEAT_SIGNALS, SELF, switch_signals, ...) {
	...
}


item (FEAT_SIGNALS, custom_signals, 0) {
	property {
		enable_signal_recolour: 1;
	}

	graphics {
		switch_signals;
	}
}