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HoI4 Dev Diary - Modding Changes

Hello, and welcome back to another Dev Diary for No Step back and 1.11 Barbarossa. Today we will be pulling back the veil a bit and show you how modders can affect and use the new features coming in 1.11.

For those of you who do not get unreasonably excited by hearing about new script commands and changes to databases, the long and short of it is this: We made some fundamental changes to the way the game handles some things, which will probably require your favorite mods to spend some time updating. On the flip side, those changes also allow for some exciting possibilities down the line. If you came here hoping for a release date, we must ask you for just a little more patience. We promise the announcement is very close - but not today.

Characters

Probably the biggest change is in how we handle people on the backend (or ponies, for that matter - we do not discriminate). In the current live version, the game has no real concept of a person as a distinct thing. It only knows about country leaders, military leaders, political and military advisors, and operatives. Cases where a country leader could also be a general had to be handled manually, leading to lots of exciting bugs when the country leader was removed but the general was forgotten about and other such cases.

We have overhauled that side of the game from the ground up with the introduction of characters. This should dramatically reduce the amount of potential zombie generals shambling around, which I am sure the non-zombie population will greatly appreciate.

Characters are defined in the common/character folder, and their definitions look like this:

Screenshot_4.png


Every character is defined as a container for different roles they can fulfill, like General (corps_commander), Advisor, country leader etc. Due to technical concerns, Operatives remain their own thing. On the character level itself, things like name and gender are handled. This also means that character names can now be localised and you can refer to a character by ID instead of by name (this helps a lot with character names that have non-english characters in them - turns out this broke some triggers and effects).

Screenshot_5.png


This also means that if a character is removed from play - say, through a purge - they are automatically removed from all roles that they could have, which makes such systems a lot easier to do script-side. It also means that if we wanted to allow Zhukov to become a country leader, we could simply add a country leader role for him in the character file, like this:


Screenshot_6.png

Or we could also add the role later on, via focus, event, decision... like we do here with Beriya:


Screenshot_7.png

That means there is a lot less confusion and duplication of effort necessary when putting a character into a new role, since stuff like portraits, name etc. are already handled. A broken portrait only needs to be fixed in one place instead of five etc.

Once defined, characters are recruited in the country history file in order to be added to the game. As you can see in the first screenshot, you can use visible triggers for unit leaders to ensure they are not shown if you don’t want them to be.

Characters that can potentially become country leaders are made into country leaders using the promote_character effect, like so:

Screenshot_8.png


This is a clear departure from the practice in the live version of the game, where you would create a new country leader in that effect. The old script with create_country_leader and other such effects should still be working, but obviously you don’t get any of the advantages of the unified character system.

So let’s talk about some more things you can do with it!

You can set and check character flags for nefarious purposes:

Screenshot_9.png


You can change the traits of advisors without having to make a whole new advisor:


Screenshot_10.png

You can check if a character is a certain type of character:

Screenshot_11.png


You can save the character as a variable to refer to them later, such as spamming debug messages in the console!


Screenshot_12.png

Tank Designer

Next, let’s talk a bit about how the tank designer works on the backend. It shares a lot of concepts with the ship designer, such as modules and module slots. It does, however, work a little differently in some other, important aspects.

While the system pretends that there are only a handful of chassis (light, medium, heavy, super-heavy, amphibious, modern), this is not technically true. Instead, the system maintains a whole host of other, dynamically created chassis. This allows us to make sure that tank designs with the tank destroyer role actually go into tank destroyer battalions etc.

However, these dynamic chassis are still generated from the base chassis, so any changes to them will carry over.

The roles are enabled and disabled on individual modules:

Screenshot_13.png



Screenshot_14.png

For the unlock of new module categories, you can then use this on a module to unlock that category:

Screenshot_15.png


Railways

Railways function a little differently from other buildings. While they are technically province buildings like forts, they are in reality closer to a building that connects two provinces. A railway line is effectively a series of two-province connections, and the lowest one in the chain determines the level of the railroad connection between two supply hubs.

To make it easier to change and maintain the historical railway setup, we have added an option to draw railways into the nudger tool, which you can access by using the nudge command in the console.
Screenshot_16.png


The railway setup is in the supply menu in the nudger, and you can easily add new railway lines to the existing setup in this way. It took me about a week and a half to do the entire 1936 setup, including tracking down reference maps (with a lot of help from some of our testers).

If you want to add railways through script, you have the build_railway effect. It gives you a lot of options, with the most basic one being to lay out the path one province at a time:

Screenshot_17.png


This is obviously a little cumbersome for longer railways, especially if you don’t really care about the exact path. For that, you have the option to define a start and an end province:

Screenshot_18.png


The game will then automatically generate a path from one end to the other using advanced neural network-based self-learning algorithms that use blockchain (read: I have no idea how it works but this sounds impressive).

If finding the province is too much work, or if you want to be somewhat dynamic, you can even use start and end states (also note that you can specify what level of connection should be built):

Screenshot_19.png


Note that you can’t mix these, so you can’t define a starting province and a target state for example.

There are also corresponding triggers like can_build_railway and has_railway_connection:

Screenshot_20.png


The first checks if a railway can be built between two locations, while the other checks if one such connection already exists.

Finally, there is has_railway_level, which checks if the specified state has a railway line in it with the specified level:

Screenshot_21.png

Miscellaneous new effects, triggers, modifiers

In addition to the things described above, we have added a number of useful things that some of you might find useful:

  • Building_cost_factor: a new modifier that affects the construction cost of buildings. This takes the buildings from the 00_buildings file, so it should work with mods that add more buildings.
  • Core_state scope list, allowing you to run effects and triggers on a country’s core states:
Screenshot_22.png


  • Add_equipment_to_stockpile effect can now take a variant name to ensure that you add the right kind of equipment.
That’s all for today, I hope you enjoyed these little insights and we are all excited about what crazy things you will do with the new tools at your disposal.
 
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Paradox, please fix -hands_off mode in NSB patch. It is broken since the last patch and it doesn't allow to run observer games anymore without using human_ai (which requires additional manual actions for each game)
 
So I am curious why tank chassis are dynamically created? You have a base model of light, medium, etc. Then flag of fixed turret or not, + other options? Seems simpler on the backend to only need to reference the defined base chassis. Of course I don't know the rest of the code but it is always interesting to hear about design decisions when it comes to programming. Usually so many possibly traps to fall into that only become apparent once you start on the feature :D

Brief looks like a nice step forward for modding!
So we have the main chassis defined for most values that are generic in the normal groupings, we then define subtypes and have modifiers/overrides only for that subtype without having to predefine all the values. It also allows you to load into the designer and design any subtype for the base chassis and what the player puts on the chassis will determine the available subtypes and selecting those subtypes will change the stats as talked about above.
 
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So I am curious why tank chassis are dynamically created? You have a base model of light, medium, etc. Then flag of fixed turret or not, + other options? Seems simpler on the backend to only need to reference the defined base chassis. Of course I don't know the rest of the code but it is always interesting to hear about design decisions when it comes to programming. Usually so many possibly traps to fall into that only become apparent once you start on the feature :D

Brief looks like a nice step forward for modding!
It was the easiest way we could tell the game that a given design is a tank destroyer and should go into tank destroyer battalions, since the entire backend is already set up for it. No need to reinvent the wheel. It comes with some unfortunate side-effects, but it did save a lot of time we were able to invest into other parts of that feature.
From a design perspective, I would usually think that having a railway connection generator handled on a state-to-state basis would go something like this:

Call function state_connect(start_state,end_state) which generates (probably randomly, but in theory any way you like) a start_province in start_state and then an end_province in end_state and then connects the two using the same algorithm that the player can use to connect to provinces (i.e. the way the game connects them via provinces instead of states)

Is the reason why you cannot simply use start_province instead of start_state (i.e. have it accept both state_id and prov_id):
1. Because provid number ranges and stateid number ranges overlap (or could in theory overlap?)
2. Some other reason
3. Just because you want to keep it clean (a fine reason!)
This is not a modding question, I don't know anything about modding, just asking
You can absolutely specify start provinces and end provinces in script. Start and end states are primarily for content designers who just want a railway to go from "somewhere over here" to "somewhere over there".
This new character feature looks promising.

Just curious if is it possible to assign multiple ideologies to one character?
Take vanilla Manchuria as an example, both neutrality and fascism have Pu Yi as leader but fundamentally they're two different "characters" defined in history file. So if I retire/kill one of them the other will still linger as a zombie.

And speaking of country leader is it possible to add an trigger for leader ideology(subtype)? Vanilla's sub-ideology really lacks some actual purposes, and its moddability is terrible without corresponding triggers and can only be accessed via brute force methods (country flag, leader trait etc) instead of directly checking in leader scope.
1634739380759.png

No Zombie Pu Yi!

The subideologies can't be checked against, and in general that whole system needs a rethink.
 
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Every character is defined as a container for different roles they can fulfill, like General (corps_commander), Advisor, country leader etc. Due to technical concerns, Operatives remain their own thing. On the character level itself, things like name and gender are handled. This also means that character names can now be localised and you can refer to a character by ID instead of by name (this helps a lot with character names that have non-english characters in them - turns out this broke some triggers and effects).

View attachment 766437
Does it means that character names will be soft-coded in Vanilla?
If so, a lot of love from Japan, because you can finally localize the names!
 
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So we have the main chassis defined for most values that are generic in the normal groupings, we then define subtypes and have modifiers/overrides only for that subtype without having to predefine all the values. It also allows you to load into the designer and design any subtype for the base chassis and what the player puts on the chassis will determine the available subtypes and selecting those subtypes will change the stats at talked about above.
I appreciate the response! That makes sense. Always fun to hear about the "why" behind things!
It was the easiest way we could tell the game that a given design is a tank destroyer and should go into tank destroyer battalions, since the entire backend is already set up for it. No need to reinvent the wheel. It comes with some unfortunate side-effects, but it did save a lot of time we were able to invest into other parts of that feature.
Half the fun of programming is getting something to work with existing infrastructure!
 
Has this been considered or discussed internally? Could it be an option in the future?
I'd really appreciate some light being shedded on this topic, as it is the lack of transparency is very disheartening to me.
 
Does it means that character names will be soft-coded in Vanilla?
If so, a lot of love from Japan, because you can finally localize the names!
That's the idea!
When youre already at adding a building cost modifier, could you *please* look into an on_built function for buildings? :3
That on_action would run a lot and probably negatively impact performance.
 
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IDs are largely obsolete now. Anything previously done with IDs is now done with the identifying token (SOV_georgy_zhukov). They are in the script to ensure that old content does not break (as much). Mods that use the exact same token for characters will probably conflict, but there is really no way around that.

Thank you for responding. I was confused then by this statement:
"On the character level itself, things like name and gender are handled. This also means that character names can now be localised and you can refer to a character by ID instead of by name (this helps a lot with character names that have non-english characters in them - turns out this broke some triggers and effects)."

So we don't HAVE to utilize an id to reference them in any script it's just option (like it is now for generals) I assume?

If so, this is a great feature. While it's cumbersome to clean up an existing mod it's clearly a better organization going forward.
 
Has the new tank designer resulted in any knock-on changes to the ship designer I should know about? I'm working on a mod for the ship designer (as well as the AI's use of it) and I'd like to know if anything might break.
 
Aww great!

Also, the hidden events for changing Franco and Mao's portrait from their young version to old has been changed according to this too, right?
 
Thank you for responding. I was confused then by this statement:
"On the character level itself, things like name and gender are handled. This also means that character names can now be localised and you can refer to a character by ID instead of by name (this helps a lot with character names that have non-english characters in them - turns out this broke some triggers and effects)."

So we don't HAVE to utilize an id to reference them in any script it's just option (like it is now for generals) I assume?

If so, this is a great feature. While it's cumbersome to clean up an existing mod it's clearly a better organization going forward.
Yeah, you effectively create the identifying token when you create the character. You can set a legacy ID, but you don't have to. Overall it should lead to a lot fewer bugs when trying to reference a specific character.
Has the new tank designer resulted in any knock-on changes to the ship designer I should know about? I'm working on a mod for the ship designer (as well as the AI's use of it) and I'd like to know if anything might break.
It shouldn't.
 
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Yeah, you effectively create the identifying token when you create the character. You can set a legacy ID, but you don't have to. Overall it should lead to a lot fewer bugs when trying to reference a specific character.

It shouldn't.

This is so cool.

This also solves my question from the prior dev diaries about how the general advisors would work.

I didn't notice, but I assume we are able to assign existing advisor/minister gfx to instead of it auto-creating them? I've figured the new system would just take the general/admiral portrait and turn them into an advisor when you promoted them, but we can set specific gfx instead?
 
The subideologies can't be checked against, and in general that whole system needs a rethink.

Yeah was really hoping that would happen as part of NSB. To me a simple, if inelegant, solution would be to separate sub-ideologies out into a decision style file. Categories would exist (communism/fascism/etc.) and could be the same setup now, but subideologies would be their own separate file where a modder could make as many as they wanted and just tag them to the right category in the file. This would allow mods to add sub ideologies without touching vanilla base ideologies.