Hey everyone! I’m Plankie and one of the programmers on Hearts of Iron. Large parts of my work consists of feature work, bug fixing, and general game improvements. My absolute favorite part of game development is working with the AI and trying to make it more fun and interesting and immersive to play with. So, in this week’s dev diary I’ll focus on showing how the AI interacts with one of our major new features: The International Market

On a very high level, there are a few things that the AI needs to be able to do in order to utilize the market:

• Gain market access so that we can see what other countries have put up for sale
  
• Sell equipment to others, i.e. putting equipment up for sale on the market
  
• Buy equipment from others, i.e. decide what we want to buy and how much

It also needs a surplus of equipment to sell, but fortunately the AI already knows how to produce equipment, so that just needs a little bit of tweaking!

The basis of the AI’s behavior on the International Market is the surplus/deficit it has of different types of equipment on the production stockpile (you know that list of equipment you see under the logistics tab). In general, it will try to buy equipment it has a deficit of and will offer to sell equipment it has a surplus of. This base behavior is then modified by other factors, such as AI strategies.


The familiar logistics tab showing what equipment is available on the production stockpile. The right-most number showing surplus/deficit is an important component of how the AI interacts with the International Market.

Before anyone can buy equipment from the AI, it obviously needs to put equipment up for sale. Just like for a human player, it is only possible for the AI to add equipment to the market if it has a surplus of it. However, just because there is a surplus doesn’t mean that it’s a good idea to put all of that surplus up for sale. And if the surplus disappears and we start lacking equipment again, the AI should take the equipment off the market so it can use it itself instead. We basically want something like the following behavior:

• If we need the equipment ourselves, don’t sell it
  
• If we have a lot of surplus equipment, start selling some of it, but not all of it

The problem is that we need to define how much “a lot” is so we know when to start putting the things up for sale. This could depend a lot on what type of equipment it is and what situation our country is in. We could do something simple and say that “if we have a surplus larger than 200, then start selling”, but 200 infantry equipment and 200 strategic bombers are on completely different scales so using absolute numbers is not a good idea. But manually having to define the numbers for different equipment types and situations and countries also means a lot of work and balancing, so we at least want some good default behavior with a possibility of tweaking it.

In one of the first iterations of the market AI, we just made it put a certain ratio (say 20 %) of its surplus equipment up for sale. Despite the simple approach it worked pretty well, and since it’s simple it’s also easy to understand and debug. It had some shortcomings so we modified it a little bit, but it’s still the basis of how the AI puts things up for sale. Every market AI update, it calculates its total surplus of every equipment type (surplus on production stockpile + anything on the market stockpile) and makes sure that the ratio is correct.

This means that if the AI needs the equipment themselves, they have a total surplus of zero, so they put 0.2*0 = 0 equipment up for sale, i.e. they won’t sell it. They will also pull back anything already up for sale so they can use it themselves. And if they have a total surplus of 100 equipment, it will put 0.2*100 = 20 equipment up for sale (assuming a ratio of 20 %). So the more surplus it has the more it tries to sell, while still retaining a buffer in case things go sour and it starts needing the equipment itself. It also means that we don’t need to specify an absolute number for the threshold, it adapts itself to the situation.

But as mentioned, the approach had some shortcomings. The AI had a tendency to “trickle in” equipment on the market, trying to sell 1 rifle as soon as it had a surplus of 5 rifles, etc, and this felt very artificial and not very human-like. This led us to modify the algorithm so that the AI thinks about the equipment in batches instead of singular weapons. The size of a batch is roughly how much equipment can be delivered in one month using one factory for payment, so instead of seeing the AI try to sell 3 rifles, it now waits until it reaches around 350 rifles (one “batch” of surplus) before putting it up on the market.

At this point we had a reasonable default behavior for how the AI puts equipment up for sale, but we still needed the capability of tweaking it. This is done through scripted AI strategies! If you don’t know what AI strategies are in HoI4, it’s essentially a way that content designers and modders can tweak the AI behavior through script. With AI strategies, it’s possible to modify things like

• how much equipment is needed before considering it as a surplus to sell on the market
  
• the ratio of equipment the AI wants to put on the market
  
• the min and max amount of equipment to put up for sale (overriding the default batch size)

With the AI strategies, it’s possible to for example prevent minor countries from selling all their trains (which aren’t used much before the war, so they are technically a surplus). It is possible to script Germany to not sell their huge surplus of weapons when preparing for war (fun fact: the German AI isn’t really aware that its going to end up in a big war until just a few months before the war breaks out, so without different scripted AI strategies they wouldn’t prepare enough for it). Needless to say, the AI strategies are a very useful tool for the designers!

If the AI is lacking some type of equipment, it will consider buying it from the International Market (assuming there is someone offering to sell it). First of all it decides how many civilian factories it is willing to spend on purchasing equipment. Second, it looks at all the available equipment up for sale and determines if there is anything there that matches what it needs. After that, if the AI has factories to spend and there is equipment it wants to buy, it’s just a matter of deciding what to buy first and how much of it. This is done by computing a score for each potential deal, a score which takes into account:

• Construction cost of needed equipment - we prefer to fix our biggest needs first
  
• How good the equipment is - we prefer newer equipment with better stats
  
• How expensive the equipment is - we prefer cheaper stuff
  
• Applicable subsidies - if we have any subsidies we prefer to use them
  
• Scripted AI weight - we want to make the content designers and modders happy

Example of a debug info window for the market AI. Here, the US AI has a deficit of 294 tactical bombers and almost 19k infantry equipment. It would prefer to buy bombers since the value of the lacking bombers is higher than the value of the lacking infantry equipment, but for the moment only British infantry rifles are up for sale, so the Americans start buying that instead.

So, now we know WHAT we want to purchase, but what about HOW MUCH? If we asked to buy 19k infantry equipment but only were prepared to pay with one factory, we could end up with a deal that would go on for years. In order to circumvent problems like these, the AI tries to create contracts that are neither too small nor too large by tweaking the amount of equipment and assigned factories until the completion time is acceptable. At the time of writing (and subject to change), the AI avoids purchasing more equipment than what can be delivered in about 10 months. It also uses the aforementioned “batch size” as a minimum limit of how much equipment to buy.


Paying off 19k infantry equipment with just one civilian factory takes a couple of years. Long-term weapon deals sound better before you do the math…

Of course there are also AI strategies for affecting how the AI purchases equipment. These are values that either go into the scoring calculation (affecting what the AI prefers to buy and from whom if there are multiple alternatives), or that tweak things like the threshold of when it wants to buy equipment of a certain type.

Now we know how the AI puts equipment up for sale, and we know how they determine what they want to buy. But all that is for nothing unless the AI has access to another country’s market, so of course it needs some way of gaining market access.

This is a relatively simple process since market access is nothing more complicated than a normal diplomatic relation, like docking rights or a non-aggression pact. Naturally, the AI is able to respond to requests for market access if you ask them, but it would be a pretty boring feature if they never took the initiative themselves. The exact factors that go into the AI’s desire to have market access with another country are of course subject to change as we balance the game, but at the time of writing the most important factors are:

• Diplomatic opinion - I really like this since I think opinion is underused in HoI4. It makes it possible for you to achieve market access with a country as long as you are prepared to spend some sweet PP to maintain it ;)
  
• Trade influence
  
• “Ideological” opinion - Some ideologies like other ideologies more or less
  
• Competing factions - If the two countries are in different factions

The Soviet Union is really not interested in opening their market to those British capitalists.

The result of this is that you tend to see something similar to trade blocs, groups of countries that trade with each other (often along faction or ideological lines). The boundaries between the trade blocs are soft, however, and it’s often possible to convince countries to trade with you by raising their opinion of you.

Finally, since the International Market revolves around surplus equipment, it wouldn’t be much fun if there was no equipment to trade with. This ties into some changes to how the AI produces equipment, especially when they have already fulfilled all their own needs.

As some of you may have noticed, since BBA a lot of smaller countries have been bad at fully utilizing their military factories. As soon as they have fulfilled all their equipment needs (including having a buffer for any armies in the field), they stop using their military factories. This behavior was not introduced with BBA, but because of some other changes to how the AI recruits armies the problem became much more visible. The reason they stop producing equipment is because they technically don’t need any more equipment, and if you don’t have any equipment you need to produce… well, they simply stop producing it. As human players, we know that a war is looming on the horizon and there is no reason to stop production just because “we have enough”. It’s better to be prepared with a larger stockpile. And with the International Market making its entry, we can suddenly satisfy our inner capitalists and earn something by selling our surplus equipment.

So, now, when the AI gets to the point where they have enough equipment to fulfill their own needs, they start transitioning into a “surplus production state”. In this state, they once again use AI strategies to determine what to produce. This makes it possible to script countries to produce different types of surplus equipment, which in turn would allow for more “equipment diversity” on the market place and a larger selection of equipment to choose from.

We are nearing the end of this dev diary, so let’s quickly sum it up!

We did a little deep dive into the AI for the new International Market feature, and got to see the logic for how it puts surplus equipment up for sale and how it constructs purchase requests. In addition, we looked at the factors affecting how the AI opens up their market to other countries, and finally, how surplus equipment is produced when all other needs are fulfilled.

I hope you found it interesting to see some of the inner workings of the market AI, and I definitely hope you will enjoy playing the game with your new trade partners! In next week’s dev diary you will get to join some of our content designers for a closer look at how to mod Hearts of Iron! Stay tuned!

Generals!

As many of you saw, the Open Beta has now been closed, but that doesn't mean we don't want to hear back from you. We know the Beta sparked a lot of discussion, but R&D want to hear directly from the frontlines!

If you participated in the Summer Open Beta, let us know in this survey below how its been for you.

Fill it out here -> https://pdxint.at/47f0R6O




That's all from us today, see you next week with yet another Developer Diary, and have yourselves a great weekend!

Greetings all,

We’re still well in the middle of Swedish vacation time, but our regular schedule is not entirely interrupted: today’s diary covers a few of the smaller features being added in AAT.


For a while now we’ve wanted to give countries a way of specializing their special forces. Numerous militaries relied heavily on these elite troops, and some branches of what HOI4 terms ‘special forces’ really found their identity during and around the second world war.

I believe we’ve reached a good saturation point for equipment designers, and I wanted to tackle special forces in a manner that better befits strategic capability over detailed stat modification. The prolonged global conflict our game portrays led to significant doctrinal development when it comes to how militaries employed elite forces, and this seemed like a good place to start.

In AAT, a fourth doctrine page has been added:


While any country can continue to make use of the Mountaineers, Marines and Paratroopers they are familiar with simply by researching the tech, doing so will unlock the ability to choose the corresponding special forces branch specialism.

These doctrines will also cost experience, however unlike the other military doctrines each branch here will use the corresponding experience type: Army XP for mountaineers, Naval XP for Marines, and Air XP for paratroopers.

The number of branch specialisms you can pick is limited however: initially to 1. Some nations earn the early ability to unlock a second (and final) branch specialism in their focus trees, but all nations that reach major status (this condition may be relaxed) will eventually earn the right to pick their second branch during the progress of the war.

Why not all 3? The [[i]Insert Country Here[/i]] military used all three of these!

Well, partly for balance reasons, and partly because these specialisms don’t represent the ability to use paras, mountaineers or marines, but the adoption of their capabilities as part of a military’s core doctrinal philosophy.

We also wanted these doctrine choices to do more than give you stat bonuses - although of course these will be present. We wanted the choices you make here to a) change how you consider designing your divisions, and b) potentially change how you actively use your special forces on a strategic level.



Initially, elevating the mountaineers will grant you a mountaineer supply usage reduction (decimal bug noted!), and some general special forces combat bonuses. Importantly, you’ll also unlock the Rangers support company: a more combat oriented alternative to mounted recon, with higher organization, bonuses in adverse terrain types, and which can be further specialized by the mountaineers branch specialism in the following two doctrines:



Here you are making the choice to train your elite ranger companies in rough+hot or rough+winter terrain. I’ve added a Snow adjuster here (usable by mods, of course - although for performance reasons this does not extend to one adjuster per weather type I’m afraid) which means you can guarantee improved combat performance in your preferred terrain/weather type, and the support company now also exerts a division-wide buff to cold/hot acclimatization.

While I won’t go through each doctrine individually, we’re making use of the new battalion modifiers to adjust how you are incentivized to build divisions:


Mountain artillery gives you a good reason to use artillery support in your mountaineer divisions, at the cost of a mutually exclusive choice with the following option:


Balance subject to change, of course.

The final choice (and a choice which exists in each of the branch specialisms) is to decide between adopting your mountaineers as the core of your elite armed forces, or integrating them more widely:


The new modifier ‘[Type] Special Forces Cap Contribution’ is a dynamic modifier that reduces the cap consumption of that special forces type, when counted against your cap. So, you’ll be able to support significantly more mountaineers, but not more paratroopers or marines.


Here you’ll get bonuses that are more applicable to a wider array of circumstances. If you plan on unlocking and utilizing a second branch of special forces, this option might be more your cup of tea.



The initial investment for the Marines branch will net you some similar small bonuses to special forces efficacy, a slight increase in naval invasion capacity (which can be acquired quite early), and you’ll unlock the Pioneers support company.

Pioneers are used here to represent marine-trained sappers and combat engineers, and will be an alternative to standard military engineers. They have increased offensive capability in notably hostile environments, and can be further specialized as shore parties or jungle climate specialists:



The second mutually exclusive choice in the Marines tree is as below. If you want to go all-in on highly elite, more self-sufficient marines, you can go down the Marine Commando route. Marine commandos are a new line battalion that have the ability to perform quick hit & run naval invasions with an equally quick getaway plan - they no longer need to be at a port in order to exfiltrate. All battalions in a division must have this ability in order for it to function.


Further down the tree you can capitalize on the hit & run playstyle:


The alternative path will take you down a combined arms path, integrating more closely with other branches of your military:





Elevating the paras will grant you tougher air transports, generally improved special forces, and the ability to field a small amount more paras.


The first choice you will have to make is which paradrop effect you want to adopt. Aimed at disruption, the recon and sabotage doctrine will damage enemy constructions after a successful landing.


Combat insertion is intended to augment well-planned general advances. If utilized carefully, this approach can put a hole in even the best fortified enemy frontline - however, the risk is high.\


It had to be done.

The mutually exclusive branches for paratroopers once again distinguish between a focus on paratrooper combat and support ability, or a wider combined-arms benefit:


Make use of signals companies to coordinate a hasty defense after a drop.


At the cost of increased training time, ensure that only the toughest recruits find their way to the paras.

Or choose to integrate the paras more traditionally into your armed forces:



And now, who doesn't like seeing some more of the 3D models?



















That’s all I have to show this time - as always, feedback on the details is encouraged; constructive criticism welcomed.

/Arheo

Generals!

Part Two of the Arms Against Tyranny Feature Breakdowns is here!

Find out more about Sweden's new content and take a closer look at the Joint Focus Trees

https://pdxint.at/3OxsrVw

Joint Focus Tree Dev Diary

Hej hei folks! Carlo here, and I’m super excited to present this new feature, probably the first to be made with multiplayer in mind. Just remember that this is all work in progress so you’ll definitely see stuff that will change for release.

Let me start with a hypothetical scenario:

You and your friends decide to play a co-op campaign of Hearts of Iron. You get your healthy snacks and drinks, jump into a voice chat and load the game, hoping to play as Monarchist Poland. There’s one problem though, one of your friends wants to play as monarchist Lithuania, and hopes to annex Poland and the other Baltic nations. If this has happened to you, then you’ll love the Joint Focus Tree. Actually I’m sure you’ll love it even if it hasn’t.

As nations that start the game disadvantaged against the big majors, a lot of minors rely on absorbing the countries around them to be able to compete. This happens with the Baltics, China, South America and importantly for us, the Nordic countries. We’re hoping the Joint Focus Tree will solve this by giving you and your friends the opportunity to collaborate with your neighbors and make your faction be more powerful than the sum of its parts, so you can take the fight to the Majors and win, TOGETHER!


But what is it? Well it’s a shared focus tree that Nordics will have in addition to the country’s normal focus tree, but when you start it you create a special faction where anyone can complete focuses in it, and they will complete in every relevant country, giving effects to all Nordic members of the faction.


Let’s take “Joint Military Exercises" as a very basic example. If Norway completes it, it’ll get 80 Army Experience and 2 75% Land Doctrine bonuses, but because it’s a Joint Focus, it will give 60 Army Experience and 2 50% Land Doctrine bonuses to every other Nordic in the faction.


The best part is that then another country, say, Denmark, can complete any focus that requires it while Norway does another focus, Joint or otherwise. You’re all working together and strengthening each other.


Other focuses give the Originator (The player that completed the focus) a special National Spirit that makes it the leader in that certain area, and because the requirements are pretty high, you will have to coordinate with your friends so each country specializes in one area to continue spreading the benefits around.


Now that I’ve explained the basic concept, let me describe how Arms Against Tyranny’s Joint Focus Tree will work:

If you’re playing as any of the Nordic countries and you’re not a puppet, you’ll eventually have the option of forming one of the three factions planned for this:

The Nordic Council: The Nordic democracies have joined forces to defend their political systems and to eradicate autocracy and oppression abroad (There’s currently an actual Nordic Council in real life, though with a different aim). They will use their resources and expertise to focus on quality over quantity, and manufacturing technologically advanced equipment, while still providing for their people.


The Northern People’s Union: The peoples of the North united against fascism and capitalism in Europe and beyond. Every worker that’s not making the tools of communism at home must take up arms and fight abroad. Expect superior numbers in both personnel and materiel


And finally, the Kalmar League: A mirror of the historical Kalmar Union, the monarchies and dictatorships of Scandinavia and Finland call upon their shared past to bring forth their common goal of domination, through armed conflict and conquest. By any means necessary.


As you can see, many of the icons, names and effects will change depending on which one fits your country’s current politics. Credit goes to Marie for her excellent art, there was a lot of back and forth to establish a unique visual identity for each faction, and they are some of my favorite focus icons in Hearts of Iron. Here’s some highlights


And you probably noticed the title background for these is different from normal ones, so stay tuned and we’ll talk about them and how you can change them yourself through modding.


Let us continue then. The JFT has 7 different branches: Airforce, Navy, Army, Civilian Production, Research, Military Production and, right in the middle, a political branch that will let you unlock institutions that improve and further customize your faction.


For example, in the Communist faction, after establishing the Northern Federation, the faction’s National Spirit improves, and then you get something I call Capstone Selectors.



When someone completes it, it will unlock 4 extra focuses at the end of the relevant branch. The first choice in the NPU is between the Army and Civilian Industry, and if we choose the Army one, 4 new focuses will appear at the end of the army branch, giving you an extra advantage on that area, and letting you adapt to the situation.


After that you can upgrade your faction again, and then you get another capstone choice, this time between Research and military production. Every one of these factions has 4 different configurations, depending on what you need, and how involved you want to be with it.



Before we finish, I want to show you what are those focuses before the one that lets you form the Joint Alliance. These are simple old shared focuses that all Nordics will have access to. They are meant to represent how they all helped each other in the period, while avoiding all out war with their neighbor’s aggressors. The best examples are Sweden, Norway and Denmark secretly sending volunteers and equipment to Finland to fend off the Soviet Union, and Sweden’s surreptitious support for Norwegian and Danish liberation against Germany. Of course with these focuses and decisions you’ll be able to go further than that and join them in their struggle, or even join their enemies and gain territory yourself.


Let’s dive in.

Reaching Out to Our Neighbors starts the decision category, and from the get go gives the option to promote Nordic Unity, letting you improve their opinion of you, especially handy if you want to form the Joint Faction with the AI.


Then you can go for Industrial Cooperation, which unlocks decisions to improve your economy and the economy of a neighbor in equal terms, if you go the other route, Leverage Nordic Investments, you can invest in other Nordics and ask them to invest in your, always with better terms for the initiator, but they’ll still get something out of it.


Mutual Guarantees is… Well… Mutual Guarantees. But Strengthen Ties is another useful one if you want to do the Joint Focus Tree, it not only makes your countries like each other more, but you’ll trade some party popularity, so if you’re communist, and they’re democratic, they will get some communism, and you’ll get some democracy, as a treat.


It concludes in the focus to form the alliance, but I want to draw your attention to the focuses on the sides. One has the name of the expansion (Mostly) and the other one is the Nordic March. They both let you send volunteers more easily and give you bonuses for combat but their goals are very different.

The TAAT focus unlocks several decisions that let you expand volunteer capacity, make it easier to send lend lease and even join the war, provided you’ve been involved in it enough participation in it. Every time you or any other Nordic helps them, the conflict scale increases, and the higher it is, the more likely your participation will go up, until your neighbor’s enemy sees you as a threat and attacks you too! It will be a balancing act for you to help your neighbors and not get invaded in the process.


And that’s it! This is how we plan to make the nations in this expansion work together more than ever, and introduce a new vessel for cool alt history. Obviously there’s tons more details that I didn’t include, but you can always ask me and I’ll try to answer where and when possible. Don’t forget to stay tuned for the next one of these, where Arheo will show you some diverse cool things!

Generals! New intel has arrived from Turbolarp about the upcoming Hearts of Iron IV Grandest Lan!

Check it out below in the Infographic we created.
For more information beyond this, check out the event website: HERE

Hello there, it's me C0RAX.

This week we are going to talk about some of the small features coming with Arms Against Tyranny, these are small things that add or change the game to increase the QoL or add to the game.

So this week we have 3 main groupings;

• Division Structure
  
• Economy
  
• Presets

First up we have division structure changes. The way you make a division has been fairly static for quite some time. With this update there are some new changes that increase the challenge and compromises you will have to make when designing your divisions.

First up we have some changes to the categories for each brigade that you choose when you pick the first battalion for each vertical column. Previously we had both artillery, AA and AT in the same category as maneuver units like infantry and tanks. This is no longer the case; artillery, AA, and AT are now in their own category meaning you need to choose how many support brigades you have and how many maneuver brigades you have. This extends to mobile battalion and armored battalion categories.


Previously there was never any real scarcity when it came to a division's battalion slots, you could generally always have whatever number of battalions you wanted in generally any mixture. Now your brigade also starts with the bottom slot locked making a 5x4 grid.this is the default state of divisions and you can unlock this 5th slot by unlocking doctrines giving you a 5x5 grid. When this is combined with the category changes you will need to think about how much combat support battalions you can bring vs vs how many maneuver battalions you you need if you want to make that large division with lots of tank and infantry you will be significantly restricting just how much Artillery, AA and AT you bring to boost your unit.




Now we are onto something many of you have seen in the focus tree dev diaries is the new modifier “Consumer Goods Factories Factor” . This new modifier exists because the Consumer goods calculation and its associated modifiers have changed.

Previously the calculation of consumer goods was calculated by adding all the consumer goods modifiers to get a percentage; it then worked out the number of factories that percentage represented against your total factory count. So if you had 5 civs and 5 mils for 10 total factories and your consumer goods modifiers total was 10% you had to pay 1 civ for consumer goods. You were then “taxed” that number of civilian factories.

This had a nasty problem in that it was very easy to first reach 0% consumer goods which was a considerable balance consideration due to it allowing faster snowballing of the economy. This easiness of reaching 0% consumer goods was then a problem because once you reached 0% other parts of the game where the reward was a further reduction of consumer goods were rendered useless since you cannot go below 0% consumer goods.

This is now done a little differently, firstly there are now 2 steps to the calculation of the percentage. First we have the base value(expected consumer goods), this works the same as the old percentage calculation; it's a simple percent value that is added up together. This generally is only set by laws so it acts as a base value that everything else modifies. We then have the consumer goods factor (the new modifier) which multiplies this value and if there are multiple factor modifiers they are multiplied together meaning that you will generally never actually reach 0% consumer goods from just the factor alone and the effect of each additional consumer good factor modifier has diminishing returns.



We have also as part of this made the consumer goods calculation round down consumer goods factories which should help minors a bit while not really being highly noticeable for majors.

For those who want a detailed copy of the calculations it's like this:

ConsumerGoodsPercent = (Base1 + Base2 + ….) *((1+Factor1) * (1+Factor2) * ….)

ConsumerGoods = Max(ConsumerGoodsPercent , MINIMUM_NUMBER_OF_FACTORIES_TAKEN_BY_CONSUMER_GOODS_PERCENT ) (ConsumerGoods * Total factories).RoundedDown

And finally I kept the most exciting one till last, and that is presets for your equipment designers. Ever since the introduction of the equipment designers we have known that some players don't want to or struggle to interact with the complexity of them especially when they are new to the features or game. This was for many off putting and something they would shy away from or be continuously frustrated with, Since the game didn’t really teach you how to make a well rounded design for each role. This was doubly true if they wanted to recreate a historical vehicle that they know from their own knowledge of WW2 but didn’t understand how to translate that into the game with the designer.

What these are are premade designs for your equipment designers that are stored in the game files. When you create a new variant from a blank chassis you can press the presets button and will get a list of all the presets made for that chassis/hull/airframe. So should you open up the improved heavy tank chassis presets you will find an entry called Tiger I and you will see the picture of the Tiger I tank and if you click it all the modules and roles and values will be set for you. Should you be missing modules or upgrades the preset entry will tell you what you are missing in order to make it, then all you have to do is research those modules and then create the variant.

So now if you don't understand or want to understand the deeper workings of equipment design you can still make good use of the equipment designers just pick the tank you want and the game will make it for you. Of course if you want to try out tweaking the designs to edge your way into the world of equipment design you can do that too. Once the preset is loaded you can adjust any part of the design as normal, and if you feel lost at any point you can just load the preset back in.



Some of you may wonder why we’re not allowing you to add your own presets or saved templates. In short, this is something we’d like to do and are not ruling out for the future - historical presets are an important step towards making custom presets a possibility.

However, this feature is entirely moddable so if you want your MP mods to have all the latest meta builds there as presets you can do that, or if you want even more templates for your super in depth history mod or maybe a totally different world you can do that. These presets are defined by the templates you make normally for the AI with some new additional fields, you can now define the art and the name of the template.

That's everything for this dev diary, I hope you will enjoy these changes as much as we have. As always feel free to let us know your favorite parts.

Next week we will be bringing you more information on a new system for content along with how it will be tied into the stories you can tell with this expansion and beyond. See you next week.

Not only do we have a Developer Diary this week for you, but we also have some intel from the Development team about some of the features coming to Arms Against Tyranny! This is the first video fo a few that we have planned for you all, so we hope you enjoy!

Make sure to check it out The Video

Hello everyone!

My name is John and I’m the 3D artist for Hearts of Iron IV here at Paradox! For this week's Dev Diary, I will be giving you all a behind-the-scenes look at my role in the team and our process for making the 3D art for Hearts of Iron IV.

My role is to create and manage all the 3D art in the game! Not all 3D art is created by a single individual, however. To save time we also have help from various talented outsourcing partners to make sure we can have as much juicy art ready for release as possible!

During this diary, there may be some terminology that may or may not be familiar to you but I will try and make sure that everyone can enjoy reading this and get a glimpse into the 3D art for Hearts of Iron 4.

Creating, tweaking, and managing all this 3D art is a lot of work but it is also a fun and rewarding process so let’s not waste any more time and get right into it!



First of all, I will receive a bunch of 3D art requests from our awesome content designers that will provide me with some general information as well as some reference images and useful links to help explain what they want to be added to the game. Doing research and finding material is time-consuming work so this is very useful to get things started.

You never know what can end up being requested. There were a lot of interesting vehicles and uniforms during World War 2 so this helps keep things interesting!

To manage all of these requests we use Miro which is a useful tool to manage a lot of images and text. These requests will be added to my 3D art board in Miro where I will sort them by things like priority and country. From here I will decide which units to work on. I will place the assets that I want to outsource on a separate board where they can be gradually reviewed along each step of the creation process. I will usually provide them with more technical feedback when it comes to the 3D art and our content designers will give input on how the asset looks from a more historical standpoint.



These are the types of images that I look at when I’m making a 3D model!


For 3D art, you generally want to have as much reference material as possible so I will usually try to add some additional reference images from the information I have been provided if needed. To understand things like angles, scale, and movement better, watching videos can also be incredibly helpful. If there are any vehicles or uniforms that still exist to this day, then this will provide greater image quality and it can also be good for color reference. It’s important to be aware of re-created paint jobs and modifications that may have been added after the war. Finding good references can be hard at times, we always try our best to stay faithful to the reference material but time is always limited so it can be easy to make mistakes. Being very meticulous and delivering a lot of assets in a short amount of time is definitely a balancing act!

The process of creating 3D art can differ a bit from artist to artist or depending on what it is that you are creating but usually, I will begin blocking out the most important shapes for whatever I’m creating. During this phase, I won’t need to care too much about the typical rules of 3D modeling. Things like that will become more important later on. The most important part here is to create the basic shape and also get a good understanding of how all the pieces will fall into place. At the end of this phase, you can use the basic building blocks that you have created to make a high-detail and a low-detail version of your 3D model. This helps save a lot of time and it will ensure that the high and low-detail versions are not too different from each other.

A block out using simple shapes.


A common trick to make sure that you have the right base shape is to disable the lights in the viewport of your 3D modeling software, this leaves you with only the silhouette. If the silhouette looks good you know that you are on the right track!

Can you guess the names of all of these vehicles?


Now we will use the block-out model as a base to start working on a version with a lot more fun details. This is the part where you can truly let loose in terms of geometry, no polygon limits are needed here! We will use this model and bake it down to our low poly version later. In short, this means that a highly detailed version of the model will be projected onto the lower detailed version to simulate detail. This will make the end product look less blocky and detailed without using a lot of polygons that can impact performance. In other words, we will get the best of both worlds!

The thing I will need to keep in mind here is to add detail to make the model interesting and accurate to the source material but at the same time, it is important to not add too much detail that will make the model hard to read from a distance. Adding too many tiny details will make it hard for the brain to distinguish between different parts of the model.


Some extra details like tools or holes will be added! These aren’t present in the low-detail version of our model. I will use colors to mask out various parts that will help me later on when adding textures to our model.

Here is the high-detail version of our tank!


It’s fun to be able to view these models up close with this level of detail so here are a few other examples of high poly models for your viewing pleasure!

Here are some high-poly models that are used for Arms Against Tyranny.


Now that we have added all that sweet-looking detail to our high poly 3D model, we can go back to the block-out version of our model to make ourselves a low-detail version that will be the version that is used in-game!

I will go through the model and make the adjustments like this!


Most of the work here is spent on removing unnecessary polygons in various ways to ensure that the model is optimized. We have a polygon limit for each type of asset. We want to stay within these limits as much as possible without sacrificing too much visual quality!

Here is the low poly version for now!


I have kept some polygons on parts that will help speed things up later on when we will prepare it for animation! It’s important to remember how the model will move, so you will also have to be careful not to remove geometry on parts that will bend. This is especially important for objects with more organic properties such as the limbs of a character for example.


Before we can start adding textures to our model we need to go through a process known as UV mapping. This is where you create a 2D map of your model so that you have something to paint on. It’s sort of like cutting a paper model into different sheets of paper that you fold out so that you can paint on them.

Once you have cut your model into all of these pieces we will need to put them into a 2x2 square that will end up being our UV-map. This process is very much like a puzzle game. The actual size of the texture image that will be used in-game is quite small so different shells will be mirrored and stacked on top of each other. This is a technique that’s commonly used in games when you want to cram as much resolution out of your texture map as possible. There are limitations to doing this, it can make camouflage or dirt look repetitive in ways that are not so appealing so we will need to be conscious of how the model will be viewed in the game. Not all artists enjoy this part but I find it to be pretty fun in its own right!

This is what our UV map looks once we have sorted everything!



If you have ever painted a miniature model in real life then this is the part where we grab our brush and start painting our model! This is honestly one of the most satisfying parts of being a 3D artist because you are no longer looking at a model without realistic materials and well.. texture!

To create our textures I will use a program called Substance Painter. I will prepare the high and low-detail models, sort the different parts by name and separate some parts from the rest of the model. After this, we will import our low-detail model into our texturing software. Once that’s done we will take our high-detail model and project it onto the low-detail model. Once this is done we get a lot of these maps with different properties that we can use for various effects when we start painting our model.

From here, it’s all about listening to your favorite music tracks (low-fi HoI anyone?!) as you add color and detail to your model. When you are texturing you will make adjustments to different values that will affect how different materials are perceived. It’s good to start with a base color and from there, add color variation as well as other properties such as how shiny or metallic the different parts should be. Working in Substance Painter is all about working with layers and masking out different parts using various methods. Thanks to the colors that we added to our high-detail model earlier we can quickly add color to things such as tiny holes as well as materials to other details such as small pickaxes and other tools. I will add some ambient occlusion to add some dark color to the nooks and crannies. This will also help separate some of the details from each other. Camouflage will be made a bit larger than in real life to make the texture appear less cluttered from a distance. Last but not least, let’s add a tiny amount of highlights to the edges to make the details pop!

A timelapse of the texturing process!


We can’t have our model be completely static in the game so let’s make it come to life with some animations! Like many things, animation and rigging is a science in itself so there are artists that specialize in this process alone. But in most cases, I will be able to create my animations from scratch or reuse older ones if needed.

Before our model can move we will need to add “bones” or “joints” that will be placed into the model. These can then be moved around to create our animation. We will place our bones in a manner that lets us manipulate how we want the model to move. Once the bones are in place we can move on to a process called weight painting which lets us tell the game exactly what part of the model should move together with a specific joint.


Now we will animate it by moving the skeleton we have created and pinning certain key poses. It’s important to get certain timings right to sell the weight and gravity that’s being applied to the vehicle as it moves. This can be trickier than it sounds but with some patience and minor adjustments, we will hopefully get the result we are looking for!

It’s alive!


Finally, It’s time to put our model, textures, and animation into the game! Once added we will make some minor adjustments to the textures and that’s that!

Tadaa!


While we are on the subject of animated assets, here is a bonus one for you! You may have gotten a peak of it if you read the Historical Finland Developer diary!

Look at them go!

And with that, our tank is ready to wreak havoc on the battlefield! Things are still under development so changes may happen here and there but I hope I was able to give you some interesting insight into the 3D art for Hearts of Iron!


This is just a small taste of all the 3D art we will have in the upcoming DLC so I hope some of you will zoom in every now and then as you play, even if it's just for a moment!

Best regards,
John

Hello there, it's me C0RAX.

A bit of the different DD than you’re used to this week. I'm here to introduce a new thing I will be doing over the summer. This summer for weeks we will be giving you the chance to test some of the balance changes coming with the 1.13 Stella Polaris patch. These changes are hand picked for testing in order to get feedback from the community on specific changes that might have large impacts. These changes will affect all three major combat groups (Army, Air, and Navy), and vary from value changes to some new functionality and behavior so be sure to read the change list so you know what you're getting yourself into.

So let's go into how this is going to work. From July 6th until August 3rd there will be a special Summer Open Beta branch on steam, this branch will have the new changes listed below. Additionally it won't have anything new coming with AAT just changes for base game and previously released DLC’s. In the last week of the test we will post a feedback form to be able to collect feedback data that we can use to analyze your responses. Of course this doesn’t mean you can’t or shouldn’t post about it outside the form, I want to encourage as much discourse, theorizing and number crunching as possible so give it a try and let us know what you think.

Now lets go over the change log.


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- updated combat width defines as per
- implemented type 2 combat widths as per
- improved some templates for planes
- balance pass on new modules
- rebalanced dismantle and conversion costs for BB engines
- adjusted damage reduction thresholds for ships

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-fixed damage reduction happening before stat initialisation
-fixed +1 to threshold values

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- Excess thrust will now increase agility instead of max speed (0.5 AGI per excess thrust)
- airframes now how base max speeds to better represent airframe size speed effects
- reduced terrain combat widths slightly, change support widths also
- major air rebalance pass for airframes and modules
- increased tech date for survival studies to 1939
- Improved aircraft turrets
- slight decrease in agility hit for large bomb bays
- small airframe can only take single turret modules
- adjusted turret stats so they are less powerful for fighters but better for bombers
- rebalanced thrust and weights of modules and airframes,
- added new modules
- Large autocannon
- Large bomb rack
- Armor piercing bomb rack
- 3 levels of torpedo mounting
- Added new techs for plane designer (see above)
- Combat better Agility and Speed has increased effect on air combat

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- Super Heavy tanks are now support units. Super Heavy tanks are no longer line battalions
- Armor skirts provide 1 more armor
- Most tank chassis' now grant 10-20% more armor
- Super heavy tanks now cost more overall, but require 20 per support company.

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- added damage reduction to piecing thresholds for naval combat
- convoy hitprofile reduced from 120 to 85 bringing it inline with new hitprofile calculations
- Ship torpedoes accuracy increased to bring them back in line with new hitprofile calculations 145 > 100
- slightly decreased AA disruption from ship AA
- removed visibility effects of super heavy bb armor
- rebalanced, ship engines
- removed visibility impacts from medium guns
- rebalanced IC costs to reflect engine changes
- super heavy armor now part of normal heavy armors
- rebalanced armors
- added cruiser armor to carriers


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- AI more likely to upgrade division in the field even with equipment deficits
- added generic AI upgraded infantry template for late game infantry
- added ENG and USA upgraded infantry templates for AI and improved their infantry templates in general

Right now let's get into some explanations.

Thrust and weight:
Let's get the big one out the way thrust and weight for planes. This change requires a bit of game explanation and some explanation of aircraft. So why affect agility, agility previously was a stat that was seldom increased but often reduced by making it something you are rewarded by not using all your thrust budget you can lessen the agility effects of modules by not loading up your entire plane creating a choice between maximizing raw damage or maximizing damage bonuses during air to air combat by bring higher Agility.

Now the aircraft stuff, so power/weight is very not intuitive for aircraft, adding more power will make a plane faster but taking weight off a plane won't make it faster since speed is almost entirely determined by thrust against drag not weight. What less weight does provide is better climb rate acceleration plus some other things. These are abstracted into agility in game. So now if you want your plane to go faster you either use a newer airframe with lower drag (higher base speed) or by putting a bigger engine in the existing airframe.

Combat widths:
Now the next big change, terrain combat widths. This is the change that originally spawned the open beta idea. These changes are generally intended to flatten the efficiencies further for combat widths while also reducing division sizes. There will obviously still be certain numbers that fit better than others but overall these differences should be less extreme.

• Terrain = CW+Reinforcement Width
  
• Desert = 82+49
  
• Forest = 76+40
  
• Hills = 72+36
  
• Jungle = 74+34
  
• Marsh = 68+22
  
• Mountain = 65+25
  
• Plains = 82+49
  
• Urban = 86+28

Ship penetration:
Finally the last change I want to discuss is the new penetration effect for ships. To put this imply they now reduce damage directly on top of reducing critical chance. The damage reductions are smaller than for land combat but that's because they have a much greater effect on the combat but be careful defeating an armored foe with just small guns should be much harder now.

Thresholds and damage are as follows




That concludes the run down of the upcoming “Summer open beta” and it's coming to you tomorrow!. I hope to see you try it out and give feedback on the changes. See you next week for more Arms Against Tyranny content coming your way. It's going to be a pretty one.