NMLTutorial/Tram articulation - Revision history

Yexo: Use CB_RESULT_NO_MORE_ARTICULATED_PARTS instead of hardcodec 0xFF

2011-12-13T22:27:12Z

Use CB_RESULT_NO_MORE_ARTICULATED_PARTS instead of hardcodec 0xFF

← Older revision		Revision as of 22:27, 13 December 2011
Line 63:		Line 63:
	</pre>		</pre>

	How this callback works is that the game runs the switch referenced in the graphics block multiple times. Every time the switch is run, it will increase the variable <code>extra_callback_info1</code> with 1, starting at 1. And every time the switch must return the identifier of a vehicle item that must be added. This can be the identifier of the item you define the callback for, or a different vehicle item. Because you can change the looks and properties of the attached vehicle parts by means of other switches/callbacks, it is fine to return the identifier of the same vehicle. If you want the game to stop adding more parts to the vehicle, you have the switch return a value of ~~0xFF~~.		How this callback works is that the game runs the switch referenced in the graphics block multiple times. Every time the switch is run, it will increase the variable <code>extra_callback_info1</code> with 1, starting at 1. And every time the switch must return the identifier of a vehicle item that must be added. This can be the identifier of the item you define the callback for, or a different vehicle item. Because you can change the looks and properties of the attached vehicle parts by means of other switches/callbacks, it is fine to return the identifier of the same vehicle. If you want the game to stop adding more parts to the vehicle, you have the switch return a value of CB_RESULT_NO_MORE_ARTICULATED_PARTS.

	This is a lot in words, but not so much in code. The switch you need is this:		This is a lot in words, but not so much in code. The switch you need is this:
Line 70:		Line 70:
	switch (FEAT_ROADVEHS, SELF, switch_articulated_htm_4001, extra_callback_info1) {		switch (FEAT_ROADVEHS, SELF, switch_articulated_htm_4001, extra_callback_info1) {
	1..2: return item_tram_htm_4001; //use same vehicle for all parts		1..2: return item_tram_htm_4001; //use same vehicle for all parts
	return ~~0xFF~~; //stop adding vehicle parts		return CB_RESULT_NO_MORE_ARTICULATED_PARTS; //stop adding vehicle parts
	}		}
	</pre>		</pre>
Line 126:		Line 126:
	switch (FEAT_ROADVEHS, SELF, switch_articulated_htm_4001, extra_callback_info1) {		switch (FEAT_ROADVEHS, SELF, switch_articulated_htm_4001, extra_callback_info1) {
	1..2: return item_tram_htm_4001; //use same vehicle for all parts		1..2: return item_tram_htm_4001; //use same vehicle for all parts
	return ~~0xFF~~; //stop adding vehicle parts		return CB_RESULT_NO_MORE_ARTICULATED_PARTS; //stop adding vehicle parts
	}		}

FooBar: fix link

2011-08-24T20:52:20Z

fix link

← Older revision		Revision as of 20:52, 24 August 2011
Line 6:		Line 6:

	== Item block ==		== Item block ==
	The item block is not that different from that of a regular road vehicle. A tram is still a road vehicle, so the http://newgrf-specs.tt-wiki.net/wiki/NML:Features feature] will again be <code>FEAT_ROADVEHS</code>. Give the item an identifier (here ''item_tram_htm_4001''), add a property sub-block and fill it like you did with the road vehicle.		The item block is not that different from that of a regular road vehicle. A tram is still a road vehicle, so the [http://newgrf-specs.tt-wiki.net/wiki/NML:Features feature] will again be <code>FEAT_ROADVEHS</code>. Give the item an identifier (here ''item_tram_htm_4001''), add a property sub-block and fill it like you did with the road vehicle.

	One important thing to know is that the <code>cargo_capacity</code> property applies to a single part of the articulated vehicle. So the total capacity will be that what you have set for <code>cargo_capacity</code> multiplied by the number of vehicle parts. This means that the capacity can only be a multiple of the number of vehicle parts. The other properties apply to the vehicle as a whole.		One important thing to know is that the <code>cargo_capacity</code> property applies to a single part of the articulated vehicle. So the total capacity will be that what you have set for <code>cargo_capacity</code> multiplied by the number of vehicle parts. This means that the capacity can only be a multiple of the number of vehicle parts. The other properties apply to the vehicle as a whole.

FooBar: complete page

2011-08-24T20:51:01Z

complete page

@@ Line 53: / Line 53: @@
 === Articulated vehicle callback ===
 === Cargo capacity callback ===
@@ Line 62: / Line 110: @@
 <pre style="color:darkblue; white-space: pre-wrap; max-height: 200px; overflow:scroll">
 </pre>

FooBar: first page contents, intermediate save, will continue later

2011-08-24T18:47:20Z

first page contents, intermediate save, will continue later

New page

{{NMLTutorial}}
''The example used here is the HTM 4001 from the [http://dev.openttdcoop.org/projects/dutchtramset/repository Dutch Tram Set]. The original code and graphics for this are by FooBar. Code and graphics are both licensed according to the GPL v2 or later. The code has been modified for the purpose of this tutorial.''

This continues the [[NMLTutorial/Tram|first part]] of the tram example. Here we'll define the tram's item block and make it articulated.

== Item block ==
The item block is not that different from that of a regular road vehicle. A tram is still a road vehicle, so the http://newgrf-specs.tt-wiki.net/wiki/NML:Features feature] will again be <code>FEAT_ROADVEHS</code>. Give the item an identifier (here ''item_tram_htm_4001''), add a property sub-block and fill it like you did with the road vehicle.

One important thing to know is that the <code>cargo_capacity</code> property applies to a single part of the articulated vehicle. So the total capacity will be that what you have set for <code>cargo_capacity</code> multiplied by the number of vehicle parts. This means that the capacity can only be a multiple of the number of vehicle parts. The other properties apply to the vehicle as a whole.

Again you need to look all the available properties up in the [http://newgrf-specs.tt-wiki.net/wiki/NML:Properties_and_variables_and_callbacks NML Documentation] and whey you do you may arrive at an item block something like this:

<pre style="color:darkblue; white-space: pre-wrap">
item (FEAT_ROADVEHS, item_tram_htm_4001) {
property {
name: string(STR_NAME_HTM_4001);
introduction_date: date(2006,1,1);
model_life: VEHICLE_NEVER_EXPIRES;
retire_early: 0;
vehicle_life: 25;
loading_speed: 25;
cost_factor: 224;
running_cost_factor: 112;
speed: 81 km/h;
power: 966 hp;
weight: 58 ton;
cargo_capacity: (38*2+26)/3;
tractive_effort_coefficient: 0.5;
air_drag_coefficient: 0;
//sound_effect: no sound
//visual_effect: use default (none)

//callback_flags: no need to set this
reliability_decay: 20;
climates_available: ALL_CLIMATES;
refittable_cargo_classes: bitmask(CC_PASSENGERS);
sprite_id: SPRITE_ID_NEW_ROADVEH; //use custom sprites
misc_flags: bitmask(ROADVEH_FLAG_TRAM); //make this a tram
refit_cost: 0; //refits are free
running_cost_base: RUNNING_COST_ROADVEH;
}

graphics {
//this will be added next
}
}
</pre>

== Adding callbacks ==
As you may have guessed, making the vehicle articulated has something to do with callbacks. These will be referenced from the graphics block within the item block. We'll also be adding a second callback that makes the capacity different for each vehicle part. The middle part of the vehicle (as you will see on the next page) is somewhat shorter and thus can carry less passengers. We can show this in the vehicle details window using a callback.

=== Articulated vehicle callback ===

=== Cargo capacity callback ===

== Total code so far ==
If you put everything in the correct order, you should now have this:

<pre style="color:darkblue; white-space: pre-wrap; max-height: 200px; overflow:scroll">

</pre>

Because we haven't added graphics, you cannot compile this into a NewGRF just yet. So we'll look into the graphics next.

{{NMLTutorialNavbar|Tram|Tram graphics}}