GDC 2019: UE4 new Physics and Destruction System

During GDC 2019, Epic presented their new physics and destruction system. It was first shown as a short appearance during the Epic keynote or "State of Unreal" talk:

Spoiler: GDC 2019 - State of Unreal (Time 56:32)

Today, a few hours ago, they uploaded a 22 min video just about "Chaos" their new Physics and Destruction System.

 

Sooo... what was the question?

 

Just letting you know about new cool game development related technology. It's an interesting watch to see how to prepare geometry to make it fractureable as well.

 

I'm pretty sure there's already a few assets on the Asset Store that do exactly the same thing.

 

Nope, currently there are none .There used to be CaronteFX asset, but it got sadly deprecated.
here are some videos:

Here is the asset in the Editor.

 

Doesn't houdini do this destruction stuff?

 

I am not that familiar with Houdini. But as far as I know you cannot have real time fractured destructions in Houdini. You have to bake it into alembic and bring into Unity, but it would not be real time.

 

Looks at *Unity roadmap* /disappoint ...they'll have something easy and cool like that eventually right? right?

 

I managed to find several:

https://assetstore.unity.com/packages/templates/systems/advanced-tools-mega-pack-43671
https://assetstore.unity.com/packages/tools/physics/dinofracture-a-dynamic-fracture-library-26599
https://assetstore.unity.com/packages/tools/physics/fracture-pro-7192

That said, what they're doing is not realtime either -- you can achieve the same thing with houdini and a couple scripts -- plus houdini allows much more refined potential on the fracturing.

 

Unity's website roadmap exists solely as a way of them saying "Yes, we have a roadmap" to the handful of people who were too lazy to watch the GDC and Unite presentations.

 

So you're saying they had stuff in the GDC/Unite presentations that isn't mentioned on the roadmap and you're calling me lazy? Sounds like they need to update the roadmap!

 

Worth noting that Unity Physics and Havok both being DOTS based are going to open up a lot of avenues for advanced physics performance like this. UE4 just has a habit of baking these things at a different feature level than Unity does.

 

Yeah I think people call it 'finished' or production ready.

 

No? A fracturing system is a pretty limited use case, as is most of UE4's implementations of things.

 

Really?!?! really? I don't even I can't

 

Yep, really.

 

Just a Heads up. Ue4 are writing a new physics engine. Destruction is just an early part of it. Eventually its going to replace the Physx with the Chaos engine, just like Unity. But I do expect that Unity 's one would be faster.

 

For what it's worth I think UE usually comes with less bugs, and they try to contain them pretty quickly on the average. But we need to mention that Unity usually comes up with more development, with more platform support and more generic solutions (this probably comes from the fact that UE primarily develops for their own products as support and release as soon as possible). However I haven't tried this particular system just yet.

 

There are a few solutions in the Asset Store, and heck you could even use the free solution.

Spoiler: Free Solution

Blender -> Fracture Tool -> Import to Unity

 

Again, thats not realtime. This is about realtime fracturing, thats not really the same thing at all.

 

I think Chaos looks quite cool in presentation.
Unreal probably has different target agenda.
However, I don't think it fits Unity long term goal.
But I wouldn't be surprised, if similar destructive system will evolve, as side effect, of moving into DOTS.

 

@GameDevCouple_I The presentation that Peter originally linked to is not real-time either. Watch it -- they clearly do design-time fracture calculations. You can do the exact same thing they do with a couple of the asset store items with a little work. Like I said previously, you can also use Houdini to calculate the fractures at different levels, import them and use a script to determine what fracture level to use, etc which would happen at real-time.

 

But does it really matter, if is generated in real time, or predefined? In the end, once playing, it provides desired effects.
No need for creation of pre-modeled debris by hand.

But what is more important, if mechanics can handle such many none-convex debris. Which is none-trivial.

 

It matters if you need interactivity (move big object below the crumbling building: the crumbling should interact with the big object). Otherwise, if it's purely for visuals and there is no need to have interactivity, precalculation is good and resource-friendly.

 

You can generate fractures beforehand and have them be real time, you just don't get to determine how, specifically, they fracture, but even Epic's solution doesn't handle this. It's "simply" a matter of having some collision checks applied to the fractured components (nontrivial, but considerably less difficult with a DOTS compatible system) and using that for the realtime bits. This is doable, and a nice intermediary between realtime and procedural, but is not exactly easy to implement. There are ways around this, but in both UE4 and Unity, you'd have to write a solution from scratch.

 

It's not really a new concept, I've made prototypes with these techniques and the store has had solutions for runtime destruction for years. Looks like the Unreal team just went ahead and committed to a built-in solution.

 

I would thought that would be possible already. Is like turning static to dynamic interaction. I think that is mentioned in very end of demo in presentation, when building collapses. But I might misunderstand concept.

For me real time fractuating means, that if we create / modify shape and number of polygons / vertices at real time, this will get updated accordingly. Just something like shaping a glass when is still hot, but immediately become brittle after we finish editing.

 

Okay, I need to work on my communication skills today. I was trying to referring to real-time fracturing: the building crumbles, onto the big object and the pieces are fracturing based on this interaction. Sorry I wasn't clear enough.
Simple collision is possible depending on the solution without further calculation sometimes.
(And I deliberately don't talk about a concrete solution, because they have different solutions for different things and I really didn't dig myself too deep in any of them, also I intended only as a generic comment)

 

The demo looks pretty cool. Do you know how it affects performance? In some examples, the glass multi-fracturing demo, it looked like it caused some micro freezes.

 

You mean feature complete and actually works in production right? No matter the use case, at least it tends to work.

 

Sounds like the UE4 one in the original posters comment is "on the fly" in real-time, which is amazing. I'm pretty sure anything on the Unity asset store you have to "prep" the gameobject so it can be fractured in real-time. I've worked with several on the asset store and you have to voronoi fracture the gameobject ahead of time, and then in most cases replace the solid object with your pre-made fractured object via a trigger of some sort.

Doing all of the fracturing/destruction in real-time without having to prep the object ahead of time would be amazing, and make game development that much easier.

 

Oh wow I clicked on the first video and was expecting to see lots of destruction and shattering, instead I got 1hour of talking and 5 minutes of visuals. I want my money back!

 

How will this help my chess engine?

Spoiler

I lied. I'm not making a chess engine.

 

Hmmm, but the video link is timstamped and should start where the destruction is about to start, plus I put the time in the spoiler title

 

I'd have to question what's the major difference between this and their already implemented version of Nvidia Apex? I know it's somewhat niche but it would of been nice to have Apex in Unity, problem is when you're doing pre-baked destruction it's a time sink rabbit hole that adds a lot of needless time to development.

 

(for reference) there rayfire for unity,
https://forum.unity.com/threads/rel...e-demolition-and-fragmentation-plugin.674593/

 

At first I chuckled a little. Then I thought of something like the chess match from Harry Potter where the pieces were made of some kind of stone. The pieces would use their weapons on other pieces and crush them to bits. Basically fracturing the other pieces into tons of small bits.

 

As cool as that'd look, with chess there is a relatively small, finite number of piece combinations, so you don't really need a dynamic system to get the same effect. The old-school approach of having a few pre-made split models with animations or physics would get the desired result with a fraction of the technical complexity.

Edit: Yeah, somewhat like that RayFire thing.

 

I don't get it, from what I've seen, even Chaos is not realtime.
Timestamp : 10:16

 

When I was a kid I used to play Red Faction on PC which let you destroy things in multiplayer games. To date I've not really got the same destruction gameplay in a multiplayer game since. Maybe I'd play Unreal Tournament 2016 when they finish it if it includes such a system lol.

 

Red Faction's destruction was basically entirely BSP brush based with a lot of heavy optimization, which is why it also had that same level of destruction available on the PS2. It's not really compatible with how modern games function and can't really be easily ported to them.

 

So the "chaos engine" looks like its free to use in UE4 - so even though the "real time destruction" is working on pre-canned fractures similar to rayfire's asset in unity - its the fact that they're giving it away for free. There are now demo and documentation that wasnt around for the original presentation - https://docs.unrealengine.com/en-US/Engine/Chaos/ChaosDestruction/index.html