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Unreal Engine 4.26-Chaos Preview now available on the Epic Games launcher

If you’ve been itching to give the Chaos Physics and Destruction System a try, without needing to compile source, this is the build for you! Now you can help us battle test and refine this system as we head towards a production-ready release.

Finding Chaos
Head to the Epic Games launcher and install Unreal Engine 4.26-Chaos Preview from the list of available versions in the install dropdown. In this binary build, Chaos replaces PhysX for all physics simulations, including cloth, vehicles, and destruction.

Note: 4.26-Chaos can be found at the bottom of the dropdown.

https://lh4.googleusercontent.com/zStvpPHqK6edj5mBrN8IltpDg1zg9FOqfLpwiRoHIDB2AVSucqKkGoCxzKX8zdZK1daDTr7Nx2qof4jZX17YIRDY_8cjLjg6w8s2IWpwWZPjdBh7jA5s8pi5a7Qik6Lj5d0_pwEV

​**Chaos-ready templates and demos **
Once you’ve downloaded the 4.26-Chaos Preview build, you can test drive the Vehicle and Advanced Vehicle templates with updated Chaos actors, and smash into the Chaos Destruction Demo, available on the Learn Tab. To get started with the Chaos Destruction Demo, you’ll need to follow these instructions on how to configure it for the new Preview.

Share your thoughts
In the wake of your destruction, please don’t forget to file any bugs you unearth and feel free to share your feedback in the comments below.

Happy developing!

Getting this trying to launch a project with it:

[2020.12.17-04.40.35:417] 0]LogWindows: Error: === Critical error: ===
[2020.12.17-04.40.35:418] 0]LogWindows: Error:
[2020.12.17-04.40.35:418] 0]LogWindows: Error: Assertion failed: HorizonNext->Vertex == HorizonEdges(HorizonIdx + 1) % HorizonEdges.Num()]->Vertex [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Experimental\Chaos\Public\Chaos\CollisionConvexMesh.h] [Line: 943]
[2020.12.17-04.40.35:418] 0]LogWindows: Error:
[2020.12.17-04.40.35:418] 0]LogWindows: Error:
[2020.12.17-04.40.35:418] 0]LogWindows: Error:
[2020.12.17-04.40.35:418] 0]LogWindows: Error: [Callstack] 0x00007ffe515bd759 KERNELBASE.dll!UnknownFunction ]
[2020.12.17-04.40.35:418] 0]LogWindows: Error: [Callstack] 0x00007ffdd37cde06 UE4Editor-Core.dll!UnknownFunction ]

This is the same error that was shown in preview builds and documented by others here: Migrating project to engine source build with chaos enabled - UE4 AnswerHub

not a bug but a feature request, please make it possible to fracture mesh based on its material ID, I mean each material ID detected on a mesh can have differents fracture settings applied! it will make the workflow much more convenient and will save an incredible amout of time when using chaos destruction for large scale project! despite saving time, it will make already setup geometry/mesh of existing projects in development compatible and you don’t have to redivide, re arrange and setup meshes to get it running destruction conveniably. :slight_smile:

Thanks for the feedback, Omarito! We’ve passed the feature request along to the team. :slight_smile:

Will this fork get updated with the official release? 4.26.1-Chaos Preview, 4.26.2-Chaos Preview, etc? Or will it stay at 4.26.0?

The Chaos Preview is great. I can get the 4.26 Chaos Demo to run? Help.

yeah thanks:)

Download ChaosDestructionDemoEditor.Target.cs and ChaosDestructionDemo.Target.cs here

and copy both into source folder, also make sure to have microsoft visual studio installed 2017 or 2019 before


chaos 2.PNG
chaos 3.PNG

Are ragdolls using Chaos too? There’s still an issue that’s been around for a while, where timedilation totally messes up ragdoll physics, especially if you’re toggling on/off different global timescales.

This issue was also present for physics objects, but that appears to be totally fixed in this version.

This build will receives updates down the line :slight_smile:

Thank you Epic :slight_smile:
Finally something good from 2020 :slight_smile:

I completely agree with Omarito, that would be really nice feature and great time saver.

This is not a BUG, it may involve performance issues. When I repeatedly adjust the parameters in the GeometryCollection, the engine will freeze or fail to respond after about 20-30s and then return to normal. The number of fragments is very small, about 30, the local computer is equipped with CPUi7-9700k graphics card: GTX3070

Is there any Chaos cloth sample?

with chaos to any plan to add a fixed update thread like the unity fixedupdate?

Request for Info. I’ve been playing a little with Chaos enabled vehicles when i noticed arrays for thrusters & airofoils, tried thrusters (for hover vehicles) but that crashed the editor, so do we have a time scale to when these options will be added.

Thanks for a better vehicle physic :slight_smile:

So this errror: Migrating project to engine source build with chaos enabled - UE4 AnswerHub

Also happens on a source build of the chaos branch. It seems that it’s a general chaos issue. Some are having it some aren’t. But it’s not launcher build related.

[2020.12.27-18.27.56:447] 0]LogWindows: Error: === Critical error: ===
[2020.12.27-18.27.56:448] 0]LogWindows: Error:
[2020.12.27-18.27.56:448] 0]LogWindows: Error: Assertion failed: HorizonNext->Vertex == HorizonEdges(HorizonIdx + 1) % HorizonEdges.Num()]->Vertex [File:E:\UnrealEngine-4.26-chaos\Engine\Source\Runtime\Experimental\Chaos\Public\Chaos\CollisionConvexMesh.h] [Line: 943]
[2020.12.27-18.27.56:448] 0]LogWindows: Error:
[2020.12.27-18.27.56:448] 0]LogWindows: Error:
[2020.12.27-18.27.56:448] 0]LogWindows: Error:
[2020.12.27-18.27.56:448] 0]LogWindows: Error:

I have tested the 4.26 chaos from the launcher a lot. It seems to be working great. Put it into 4.26.0. My opinion.

Chaos is ignoring the global gravity override, objects fall at the same rate whether gravity is set to 0 or -1 billion. So it isn’t possible to do zero-g simulations. Movement components still obey world gravity, so I know the problem is just chaos. Is this not quite at feature parity or is there another place to modify global z gravity?

Downloading now, I explicitely want to test ragdoll physics and check if things have improved in terms of stability there.
I hope for no more odd constraint violoations flipflaps, maybe a self-trap check for constraints. More stable simulations on irregular frametimes, as a user before me noted, a better simulation when time dliation is present, better performance when several complex ragdolls are active, aaand so on.

Edit: Ok tested it very briefly by simply porting one of my ragdolls over and doing some simulations in the phat editor and the main viewport. There are several issues that I cant get into more detail because I tested it over a remote desktop connection and it was fairly laggy but I compared in that same session also the ragdols from my original project and even through the remote desktop the results were worlds apart. When im back home and have access to a proper machine for testing Ill get you some more info. But right now things have drastically changed for the worse in terms of certain ragdoll behaviors. Hopefully it gets solved even before I get back to testing it better in the next year.