# Nvidia flex broken? **URL:** \ **Category:** C++\ **Tags:** unreal-engine, Engine-Source-Code, GitHub, Engine-Source-GitHub\ **Created:** [February 19, 2019, 1:38am UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567 "2019-02-19T01:38:31Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Smotsucg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Smotsucg](https://forums.unrealengine.com/u/Smotsucg)\ **Post date:** [February 19, 2019, 1:38am UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/1 "2019-02-19T01:38:31Z")
I’ve been trying off and on since I started my project to get Nvidia flex working. since unreal engine surprisingly has no native soft body physics. (it’s 2019, come on guys.) I’ve made a github account, linked accounts, gotten github for windows, branched, forked, knifed, spooned, ran the setup.bat and generated project files. Still when I try to open the “flexproject” it says “Failed to launch editor” super helpful right? no reason why it failed - just that it failed. Infuriating. I can switch engine versions by right clicking on the project file and switching to an engine version I know works BUT when I do so I get a slew of errors including; /Game/TestPackages/Flex/(asset name here) : Can’t find file for asset. /Script/Flex (don’t know why that’s gone) flex doesn’t include any sort of readme or documentation, and the internet is less useful than usual as far as google searches. ps; I’m NOT a programmer, this is why I have to resort to making angry forum posts at 8:37 pm on a Monday because my monkey brain can’t be bothered with retaining how coding works. anyway, anyone who has gotten Flex to work. please let me know what magic you worked to get it to that point. Thank you. -Cam. ---
**Author:** ![Gallonmate](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Gallonmate](https://forums.unrealengine.com/u/Gallonmate)\ **Post date:** [February 19, 2019, 9:14am UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/2 "2019-02-19T09:14:19Z")
Did you compile the engine in Visual Studio without any errors in the log? Step 5: > [@](#): > > Load the project into **Visual Studio** by double-clicking on the **UE4.sln** file. Set your solution configuration to **Development Editor** and your solution platform to **Win64** , then right click on the **UE4** target and select **Build**. It may take anywhere between **10 and 40 minutes to finish compiling** , depending on your system specs. ---
**Author:** ![Smotsucg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Smotsucg](https://forums.unrealengine.com/u/Smotsucg)\ **Post date:** [February 19, 2019, 9:08pm UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/3 "2019-02-19T21:08:09Z")
Okay, I’m an idiot and didn’t read all the way through. I missed that step. It works fine now in v4.19 is there any way to port the changes to a new version of the engine? ---
**Author:** ![Gallonmate](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Gallonmate](https://forums.unrealengine.com/u/Gallonmate)\ **Post date:** [February 19, 2019, 10:03pm UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/4 "2019-02-19T22:03:05Z")
You mean port flex to 4.21? Yes it’s possible. You would need to know some c++ and the UE4 engine changes, if you follow along this thread here it sort of explains it: [https://forums.unrealengine.com/community/general-discussion/24447-nvidia-gameworks-integration?p=1568578#post1568578](https://forums.unrealengine.com/community/general-discussion/24447-nvidia-gameworks-integration?p=1568578#post1568578) > [@NVIDIA GameWorks Integration](https://forums.unrealengine.com/t/nvidia-gameworks-integration/16686/5287): > > The main issue with FleX is just the work amount, I haven’t encountered any showstoppers there, I just simply don’t have time to fix all the issues. Main thing that will keep people busy who will try to port it to 4.21 is the physics changes but you can find plenty of examples of the new physics interface on the code base (this is how I ported Blast to 4.21). The newest working flex was ported by 0lento for 4.20. You can see all his porting/custom work here: [https://github.com/0lento/UnrealEngine/tree/4.21-GameWorks](https://github.com/0lento/UnrealEngine/tree/4.21-GameWorks) Keep in mind he has flex 4.21 wip listed in his git but he only put it up so that someone else could attempt to finish the work needed. ---
**Author:** ![Smotsucg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Smotsucg](https://forums.unrealengine.com/u/Smotsucg)\ **Post date:** [February 19, 2019, 11:48pm UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/5 "2019-02-19T23:48:33Z")
Alright, I’ll mess around with getting that going tomorrow. How well versed are you with using Flex? ---
**Author:** ![Gallonmate](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Gallonmate](https://forums.unrealengine.com/u/Gallonmate)\ **Post date:** [February 20, 2019, 12:52am UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/6 "2019-02-20T00:52:26Z")
Spent a few days on/off experimenting and screwing around with it. Seeing what it could do. Ended up making this [![](https://d3kjluh73b9h9o.cloudfront.net/original/4X/1/b/5/1b523d7c404555130afe8e97f2102e49982efb8a.jpeg "Soft body Vehicle Collision - UE4") ](https://www.youtube.com/watch?v=jhE_WlNhPps) ---
**Author:** ![Smotsucg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Smotsucg](https://forums.unrealengine.com/u/Smotsucg)\ **Post date:** [February 20, 2019, 2:15pm UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/7 "2019-02-20T14:15:51Z")
oh, you’re why I considered flex as an option! in that demo were you using wheeled vehicle as a class? if so, how did you get the body to stop lagging behind the root? that’s an issue I’m having. ---
**Author:** ![Gallonmate](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Gallonmate](https://forums.unrealengine.com/u/Gallonmate)\ **Post date:** [February 20, 2019, 10:27pm UTC](https://forums.unrealengine.com/t/nvidia-flex-broken/122567/8 "2019-02-20T22:27:23Z")
I know the default ue4 vehicle class has physx/collision lag compared to the vehicle actor’s root. I never looked up any fixes for it. I didn’t really do anything special for mine, so it still has lag compared to the root. I just made the default vehicle invisible and you can only see the flex body. I tried to explain in the video it’s not a fully working game mechanic, just wanted to show that flex can do more than what I’ve seen people use it for. I never even bothered to try and put/show wheels with it. I’ve love to experiment more with vehicle damage systems but my current project and focus is unrelated ☹