How Destruсtion Works in Control

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Revolutionary Destruction System in Control

In 2019 game studio Remedy known for Max Payne and Alan Wake has published their new game — Control. Remedy’s games are famous for their mystic stories and interesting gameplay and visual features.

In Max Payne 1 the players were investigating an origin of the Valkyr drug, in Alan Wake — fighting evil with light and flashbang grenades. And in Control they are learning about the Oldest House — mysterious organization which explores paranormal abilities and parallel universes.

Talking about features:

  • in Max Payne the players could slow the time, jump out of cover and kill enemies with low risk of being hit;
  • in Alan Wake there was good dynamic lightning system, particles and other visual effects;
  • and Control has a remarkable destruction system. Almost everything you see can be destroyed into pieces: walls, floor, furniture, books; literally everything.

Destruction in Control looks so good compared to any other modern game. In most modern games you can only break windows and lightbulbs, sometimes even shoot off some branches from the trees. In Battlefield V you can destroy some houses and fortifications, but only if they were scripted to be destroyed.

And in Control you can destroy everything because the destruction system is procedural and not scripted like in other games. Let’s talk about how it’s done.

How the destruction works in most games

Destruction is an object transition from “full” model to “destroyed” one. It means that 3D artists must create two models for every object. And VFX artists must create effects and particles to show the destruction process. For example, when you break glass you expect to see shards of glass falling down. 3D artists must create them too.

So the game developers have a choice: to double the work of the 3D modellers or to throw away the destruction system.

Sometimes the developers decide to do destruction without a “destructed” model and portray damage as particles and effects only. This will work for small objects like fruits and dinner plates and you can meet this feature in every second game.  See how it works:

Battlefield games have their own destruction system called Levolution. It can “cut away” pieces of walls, ceilings, fortifications and even destroy whole buildings. This system is fully scripted. For example, the wall consists of few chunks which fall off after receiving damage. So the wall can be broken only in particular places and not where a player wants.

How the destruction works in Control

Control game designer decided to use the principle of granularity to make everything breakable. Granularity describes every independent object, its fragment or particle equally, so they will behave equally too. These granules are divided into 3 ascending levels of details.

The 3D artists still must create particles and fragments for every destroyable object. But with one feature: they make unique fragments for every material and not for every object. For example, if you have 20 types of concrete walls with different textures, you need to create only a few concrete fragments.

The Northlight engine understands what type of material the object is built and releases matching fragments and particles. For example, if the player shoots a houseplant, the engine makes the part of a plant disappear and spawns some leaves and green particles. If the player shoots the wooden shelf, it transforms into the flying wooden chips and dust.

The work with fragments isn’t done. Northlight engine work with them like with rigid bodies, while other engines don’t even consider them as physical objects. So the player gets an illusion of the destroyed object falling to pieces like a real one.

Actually, the Control developers created a procedural destruction system which makes all the work done. Every explosion and damage is unique and done by physical engine.

Many games use similar techniques to simulate fragments and particles. But the difference is that objects in these games aren’t destroyed properly: they disappear totally or don’t change at all. And in Control you can completely destroy something part by part.

How the partial destruction system works

To make the objects naturally fall apart the developers divided them into chunks. For example, an ordinary wall is made of chunks, like a jigsaw. The chunks aren’t aligned perfectly because it’s not needed. The chunks are connected with each other with joints. If one chunk is hit, its joints are destroyed and it falls off the wall. The engine applies decals to neighbour chunks to make the destruction look pretty.

The chunks can be divided into smaller chunks. For example, the player can break a wall into 4 big fragments. Then the player can break one fragment into smaller ones. The engine will apply the same decals and particles to every broken part.

This trick with joints serves three reasons:

  • first, it helps to make almost every object vulnerable to the player with big gun;
  • second, it lowers the CPU load because an object falls into few big pieces instead of dozens smaller;
  • third, it looks more natural. When you drop a glass cup on a floor it will break into 3-4 fragments and not into the dust.

The problems with destruction system

This system may cause heavy lags and CPU throttling so Remedy put a lot of work in optimization. For example, they’ve limited the game to show no more than 200 objects at the same time. If there are too many chunks flying in the air, the engine will destroy them into sprite particles on its own to lower the CPU load.

If there is an explosion on the screen and every chunk is moving fast, the collision system turns off for the next 10 frames. Big part of flying fragments will simply fly through the walls and the engine won’t calculate them further — and that’s the point.

Also the developers teached the engine to count enemy’s weapons. For example, if the upcoming enemies have plenty of grenades, the engine will disable part of destruction system for the particular room. Besides the optimization it also helps the player to not get lost into explosions, dust and flying concrete.

What’s the point in the destruction system?

There are several advantages:

It looks cool. Many gamers bought the game just to taste the ability to blow up things with powerful guns and superpowers. Also Remedy added Ray Tracing to the gamers with high-end GPUs.

Destruction gives the player a feeling of impact and convinces him that the strange looking gun is a dangerous weapon. For example, in Call of Duty you can fire the anti-tank rocket into the wooden fence and it will stand as nothing happened. And in Control you can see how every shot is tearing surroundings apart.

Destruction is a part of gameplay. The main character has a superpower to grab and throw things like chairs and fire extinguishers. If there’s nothing to grab, the heroine will snatch a chunk from the wall or floor.

Is it necessary to make a system like this for every game?

No, it will work good only in single player games. The problem is that destruction is CPU heavy: it needs to calculate collisions and acceleration for a hundred more objects than usual. And in multiplayer the CPU is 50-90% loaded with calculating and extrapolating other player’s actions.

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