WML for Complete Beginners: Chapter 6

English

Index
Introduction
1 - Syntax
2 - The Userdata Directory and the Campaign Folder
3 - The _main.cfg
4 - Creating Your First Scenario
5 - Events
6 - Custom Units
7 - Variables Introduction
8 - Non-scalar Variables
9 - Macros
10 - Logic
11 - More Logic
Conclusion

Chapter 6: Building and Including a Custom Unit

Sometimes campaign authors only use mainline units in their campaigns. Other times, however, they may want to include a custom unit that isn't found in default Wesnoth. Thankfully, including a custom unit is quite easy.

Creating the Unit .cfg File

Create a new text file in the "units" folder inside the campaign folder. You could name this "my_first_unit.cfg".

As usual, start with the textdomain and toplevel tag:

#textdomain wesnoth-my_first_campaign

[unit_type]
[/unit_type]

A somewhat minimal set of initial keys might be:

id=
name=
image=
movement=
hitpoints=

"id" and "name" work like usual. "movement" is interesting, because by default a unit will have no movement; quite a boring unit! The same goes for hitpoints; you would have 1 hitpoint if unset.

Filling these out, you might end up with:

#textdomain wesnoth-my_first_campaign

[unit_type]
    id=My First Unit
    name= _ "My First Unit"
    image=
    movement=10
    hitpoints=10
[/unit_type]

Creating Unit Images

If you were to spawn this unit now, it would look quite strange, because we have not yet assigned an image. Creating Unit Art describes how to do this in some detail. When you have a reasonably suitable image, you should save this in add-ons/my_first_campaign/images/units.

Update your my_first_unit.cfg:

image="units/my_first_art.png"

If you don't have a perfectly sized image, you'll notice your unit looks strange in menus and when placed on the map. You can also play with the SCALE and CROP functions to adjust this:

image="units/my_first_art.png~SCALE_SHARP(72,72)"

This is described in more detail in ImagePathFunctionWML

Including the Custom Unit in your Campaign

You can now add your units to _main.cfg:

[units]
    {~add-ons/my_first_campaign/units}
[/units]

You might also want to make this unit recruitable by your human-controlled leader in scenarios/my_first_scenario.cfg:

recruit="Elvish Fighter, My First Unit"

Try recruiting your first unit!

Attacks

You will notice quickly that your unit is not able to attack, because we have not assigned it any attacks.

[attack]
    name=sword
    type=blade
    range=melee
    damage=4
    number=1
    icon=attacks/dagger-human.png
[/attack]

This is a simple sword attack, reusing mainline art for the attack icon.

Your complete unit_type tag should now look like this:

[unit_type]
    id=My First Unit
    name= _ "My First Unit"
    image="units/my_first_art.png"
    movement=10
    hitpoints=10    
    
    [attack]
        name=sword
        type=blade
        range=melee
        damage=4
        number=1
        icon=attacks/sword-human.png
    [/attack]
[/unit_type]