Call to Arms - Gates of Hell: Ostfront

Call to Arms - Gates of Hell: Ostfront Development update #97: Damage model and armor

Version
Development update #97: Damage model and armor
Version Date
March 15, 2021
Links

Patch Notes

Development update #97: Damage model and armor



One of the things some people asked about lately was to get more information about our armour and damage model. Today we will explain how our damage model works, what it takes to accomplish such a system, and why we did this.

Damage System



Let’s start with the question of why we built a new system.
Previous games in the GEM engine, such as Men of War assault Squad 2, feature a highly intertwined and outdated damage system where it has health and RNG combined. Each tank has an amount of durability, which is deteriorated until it breaks. The amount of damage dealt is a multiplier of the penetration or blastwave. So, if you get up close and shoot with a small AT rifle with high penetration, you will deal more damage than a big gun with 10x the shell size, but shooting from far away.
This was absurd, and therefore required the MoW developers to add an additional random chance of breaking the component when pierced. So a big shell had a big chance of breaking or exploding the vehicle. But otherwise, if you were unlucky, it would deal no extra random damage and you were better off with an AT-rifle!
Some players may feel it’s “pseudo-realistic” to fire a 88mm shell at a vehicle and have a random chance of exploding it or a chance it does nothing. While this makes the gameplay more unpredictable and spontaneous, it most certainly is neither realistic nor fit for competitive or calculated gameplay. We absolutely wanted to change this.

Our armour model is very complex yet consistent, so that it benefits those players with intricate knowledge of vehicle warfare and promotes studying the different vehicles, their armour thicknesses, and the position of internal components.
All our vehicle’s components have a set of real hitboxes. Our components are: Chassis, turret(s), gun(s), engine, fuel, ammo rack and transmission. This list is longer than in any conventional RTS game out there, but we want a bigger list of damageable vehicle systems for a more immersive and compelling experience.


HD link

If you pierce any of these components, an amount of damage is dealt to the component. It is possible to damage more than one component with one shot; if you manage to pierce the hull and it still has enough kinetic energy left to pierce the ammo rack, you will deal damage to both. Each component has a certain structural integrity, which is damaged by the penetrations or blasts. When the integrity is depleted, the component may be broken, and then destroyed.

Here is where the system gets realistic and deep: The amount of damage dealt depends on multiple factors. The size of the shell primarily. Does the shell type have fillers which cause internal blastwaves? (APHE will deal more damage than regular AP). The kinetic energy of the shell also has a big impact (if you pierce with more speed and penetration power, there is more energy induced into the internal spalling and speed of shattered fragments, ergo, more damage). Due to the combination of all factors, no two penetrations will deal the same damage. We do not have random damage factors explicitly inserted into the equations, the natural variance of all the factors does that for us.

To add diversity and spontaneity to tank combat, the breakage of certain components may trigger one or another consequence, always consistent with the end result. For example, if you pierce the ammo rack and destroy this component, it will mean there will be an ammunition ignition inside the vehicle which will always lead to its destruction, unless it has no ammo. It may cause an instant explosion, or it may cause a cook-off, or it may cause a very slow cook-off if the amount of ammunition remaining is not very plentiful. Needless to say, you will not cause any of these ammunition ignition events if your shells do not reach the actual ammo rack area. No longer is this a random chance when piercing any part of the hull.


HD link

Both the projectile damage dealt and the structural integrity of the components have mathematical values associated with them, which are not seen by the player. They simply help with consistency and to be able to make the system work in a logical manner. Therefore, we don’t consider them ‘healthbars’, because they are neither visible as a “bar” nor they represent health. They are a “helper” to make things consistent. For example, it takes 2-3 successful penetration shots from a 45mm 20K shell to disable the hull of an enemy Panzer III. If you are shooting at the ammo rack you may get to disable the vehicle with one or two shots. If you shoot APCR which has no HE filler, you will require more shots, but the higher penetration will mean your shots are more likely to penetrate in the first place. If you shoot once at the turret, once at the hull, once somewhere else, you will end up killing the vehicle crew members in the different compartments but not so much actually disabling the vehicle because you’re not focusing your fire. This could be a good tactic for killing the crew and capturing a vehicle!

Next. You destroyed the fuel component. Is it a diesel or a gasoline-powered engine? This will determine a very flammable or less flammable result. One more layer into the system.

All in all. The realistic aspect and detail of our damage model means you can achieve reliable results if you know what you are doing. Another example: you are a german Pak-38 shooting at a soviet T-34. You are an experienced player who knows where the fuel, ammo, transmission and other components are located inside the T-34. You should not shoot at the engine nor fuel area, because it’s a diesel vehicle which has less volatility than a gasoline counterpart. You also have issues shooting at the superstructure, because your shells have a small caliber (50mm) and this, combined with poor normalization in your APCR-shells, have issues against the sloped armour of the T-34. Read about penetration mechanics HERE. You should aim for the hull to disable the vehicle, but you will aim between the second and third roadwheel, because under those wheels there is vertical flat armour and a juicy ammo rack behind the armour.

Which leads us to another topic: do not be hesitant to shoot in between the wheels on the track area. For the first time in GEM2 games, we model our wheels and our track hitboxes accurately. This means you can shoot in between the wheels, and the shot will not be “caught” by the tracks.
Tracks are not the only hitbox accurately modelled. Do you know you can kill an enemy AT-crew member with your sniper by shooting in the aiming holes in the shields?


HD link

As you can see, this system is very deep. Some players may be “concerned” that it always takes around the same amount of shots to take out a tank in the same situation. But the hard reality is, the system is consistent and if you keep aiming at the same spot with the same shell from the same distance, it’s likely that you repeat similar input every time. Just learn how to do it better! We plan to do something in the future to enable people to learn the different vehicles better.

It takes a lot more time to model vehicles this way. But it’s worth it if you know what you are doing!

Brave men in metal coffins



The crew will not be spared from this armour redesign. The first thing we did was to ensure crew stunning and deaths are conditional to where the penetration happens. Only when being pierced in specific locations of the fighting compartment will specific crew members be likely to die. And the size of shell and the type of ammunition on impact will naturally have an important effect on the crew’s survival chances. What would you rather be subjected to? A high velocity projectile that makes clean holes without splintering and may or may not hit you, or perhaps a HEAT shell causing a jet of superheated plasma and molten metal squirting in all directions?

We introduced a seat replacement mechanism. If your gunner is dead, this is obviously a very important position which you will want covered to regain the fighting abilities immediately. But it will take several seconds for a replacement crew member to retake that seat.

Damage visualization



To make the system more manageable, we redesigned our vehicle damage visualization accordingly.
In the vehicle view, it is now possible to see the state of your components. A clear image will tell you your vehicle is fully functional. As it becomes red, it’s becoming unserviceable, because it was damaged from piercing shells or from explosion blastwaves. What we try to represent here is the crew’s assessment of the state of the vehicle: If your vehicle had been damaged, you’d be able to evaluate the functionality state of the systems, but never a quantifiable number which tells you the structural integrity remaining. So we went for the colour-coding. In previous GEM games, one could not tell the state of components, except when they were broken.

HD link

When a component is red, you can repair it. When it is black, it’s destroyed beyond repair, such as a wheel torn off. Tankmen and engineers can repair more quickly than others, but nonetheless any infantry can repair. Repair kits are limited, and you can replenish them with engineering vehicles. It didn’t feel right that you could endlessly repair vehicles with one kit, like on previous games.

Moreover, we also represented minor repairs into the game. If your turret is damaged but still functional, you can repair it and ‘patch’ it up to mint condition. You will, however, still be depleting one repair kit, so you must be cautious. On the other hand, you will have a more survivable vehicle in a better condition when going into combat again, which may give you an extra edge.

So that’s the real story of our damage model. Some people are under the impression our armour model is that of vanilla CtA, or ‘Men of War Assault Squad 2’ or other games in the GEM2 series, but as you have now seen, this is definitely not the case.

Another surprise



Talking about armour systems and tank combat, we have been developing for some time a highly realistic and intricate redesign of 3rd person. Every tank will have realistic gunsights, with realistic zoom (magnifications) to add to the experience.


HD link

You will be able to appreciate how AT guns and dedicated tank destroyers were more suited for precise firing (most of the time) thanks to their superior optics. Since we know there are people who like third person and people who like the classic direct control, we made both systems work at the same time, at your convenience, so the player can switch in real-time between his preferred mode. More about this later.

As you can see, we’re working hard for beta phase 2. Stay tuned!