NML:GRF

From GRFSpecs
Revision as of 00:39, 9 September 2011 by Planetmaker (talk | contribs) (grf parameters are part of the grf block. Move them there)
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Block Syntax

GRF block

Syntax:

grf {
	grfid: <literal-string>;
	name: <string>;
	desc: <string>;
	version: <expression>;
	min_compatible_version: <expression>;
	<param { ... }>
}

Example:

 grf {
 	grfid: "AB\03\02";
 	name: string(STR_GRF_NAME);
 	desc: string(STR_GRF_DESC);
 	version: 1;
 	min_compatible_version: 1;
 }

GRF parameters

As part of the grf block you can specify some parameter settings that the user will be able to change as part of the newgrf configuration. These can for example be used to disable parts of your NewGRF or to change between multiple graphics in case that's not possible at runtime. In general the settings (sub-)block looks like

param {
	<name> {
		type:    <type>;
		name:    <string>;
		desc:    <string>;
		min_value: <expression>;
		max_value: <expression>;
		def_value: <expression>;
		names: {
			0: <string>;
			1: <string>;
			.
			.
			.
		};
	}
}

Looking at the single entries:

type

This defines the parameter type. Possible values are bool for on/off statements or int for positive integer values

name

This gives the parameter name as shown in the parameter configuration dialogue of OpenTTD.

desc

This gives the description which is displayed when the parameter is selected. Here you can explain the meaning and impact it will have

min_value

The minimum acceptable value for the parameter (makes only sense for type int)

max_value

The maximum acceptable value for the parameter (makes only sense for type int)

def_value

This sets the default value for this parameter. If left out, the default value of 0 will be used.

names

If you chose type int and the numbers themselves are only used internally, have no direct numerical meaning and are better explained in words, you can use this to associate the single numbers with a string which describes it and is shown to the user instead of the value. A simple example:

 param {
 	param_provide {
 		type:    int;
 		name:    string(STR_PARAM_PROVIDE);
 		desc:    string(STR_PARAM_PROVIDE_DESC);
 		min_value: 0;
 		max_value: 1;
 		def_value: 0;
 		names: {
 			0: string(STR_PARAM_PROVIDE_ENGINES_AND_WAGONS);
 			1: string(STR_PARAM_PROVIDE_WAGONS_ONLY);
 		};
 	}