PhysX Touchbend and Wind

We recently updated to 1.28 from 1.25 and have been using touchbend vegetation and cry wind for vegetation. Does anyone know how to update touch bend and wind with the now physx only systems? I see that wind uses force regions and tags, but my automerge vegetation doesn’t respond. FBX’s set up for touchbend now print errors when in a scene “[Warning] Warning: Skinned geometry used without character instance”.

I believe you probably need a rig for your automerged vegetation. Or a root bone at least.

They are rigged in this case. I believe automerge ignores rigging, though. I know it is incompatible with touchbend.

I just know that it didn’t work for me until I made a rig for my grass with actor component

The touchbending FBX pipelines were updated when PhysX support was added. See the new documentation here: Adding Touch (Collision) Bending Effects - Lumberyard User Guide .


Since the switch to PhysX-based touchbending, “automerged” vegetation is not touch-bendable anymore.

Wind bending should still work, but bending due to a PhysX Collider touching vegetation instances doesn’t work if the vegetation is “automerged”.

Thanks for all the replies everyone! I was using physx collisions with touchbend before we updated versions, so I am familiar with the physx workflow and it was working correctly in my project. I reviewed this guide and it is still the same as when I set up these touchbend meshes - so I do not think the fbx set up is the issue here.

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I know that automerge ignores some other functionality - but in this case my automerged vegetation simply does not respond to force regions tagged to be used as wind - so there is no wind bending at all unless I disable automerge. This was not the case in 1.25 for me, but I was using cry wind at the time. The touchbend vegetation actually does respond to the physx wind (as does all non-automerge veg that is set up correctly), but does not generate colliders to carry out touchbend physics in the scene with actors etc.

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Following up here since I am still unable to find an answer to this.

Is there a gem, game sample, etc where I can find a working touchbend example for Lumberyard 1.28?

Has anyone verified that it works with the dynamic vegetation system in 1.28?

I hate to “bump” on forums, but my last question is entirely reasonable. Is there no working example of this feature in 1.28 that can be seen in a gem or other material provided to developers? If I can see a single working example, I can likely replicate what was done.

I have followed the docs carefully, and cannot get global wind with merged meshes or touchbend to work any longer.

I had both working before the removal of cry physics. Touchbend was using physx before this removal, yet it no longer generates bones.

The new global wind via force regions will act on my vegetation correctly, but it will not act on merged mesh vegetation - which is important for draw call reduction.

Please advise, thank you.

Hi @Hothtrooper44 ,

Sorry this issue is still happening. I’ll paste here the response I sent you by DM to share it.

"When vegetation uses automerge, it merges everything together and it expects to use the cry wind parameters instead of physx force regions. So it seems like automerge + physx force regions are incompatible with each other at the moment.

This page (Using AutoMerged Wind Bending Effects - Lumberyard User Guide) specifies that “When AutoMerged is enabled, touch bending, vertex colors, and detail bending settings are all ignored, and vegetation movement is defined solely by the AutoMerged parameters.”

Just to confirm, does everything work as expected without AutoMerge?

To gather also more details of your specific problem, it’d help if you could share the exact steps you do, a video showing these steps and the result would be very useful. Even sharing a simple level you use could help for us to replicate your scenario and give you a more accurate answer.


Hi Aaron, thanks for following up.

The global wind regions do work when automerge is disabled.

I had never gotten a definitive answer as to if it was an issue I could try to fix, or core vegetation systems are simply broken in the final version of Lumberyard before it moved to Open3d. I assumed someone else had it working before this version was published, and I would be able to as well.

The setup for touchbend is not different from around version 1.25, and the engine still has my touchbend FBX’s recognized and set up in the fbx settings files for them. They just no longer create bones - and I am not using them as merged meshes, as I know they never worked in that way.

There is a file called “orb_plant.fbx” that is included with starter game. It is set up for touchbend, and it worked in previous versions. This should be a good example to look at. I can provide something else if needed - but if this file works, or can be made to work, in 1.28 that would answer a lot of questions.

Thanks again!

Hi @Hothtrooper44 ,

I’m afraid AutoMerged vegetation + PhysX wind are not compatible, it’s not an bug, it’s a known limitation.

The alternatives are:

Sorry there is no way at the moment to use both AutoMerge and PhysX features at the same time.

my automerged vegetation simply does not respond to force regions tagged to be used as wind.

Correct, force regions rely on PhysX, which are not compatible with AutoMerged vegetation.


I tried LY 1.28 and by default touchbending doesn’t work. Cry physics must be disabled first.
Edit the file:

And disable cryphysics with this line:
setattr(bld, ‘enable_cry_physics’, False)

Reconfigure the project, and rebuild. Before rebuilding it is recommended to delete dev/BinTemp/ folder and dev/Bin64vc142/ (if you are using VS2019) or delete dev/Bin64vc141/ (if you are using VS2017).

Hey Lumbermixalot - thanks for the reply.

So you have touchbend working in 1.28 personally?

The steps you listed I have already taken - so unfortunately that would not be what has gone wrong.

Attached is a test level you can use inside StarterGame. (175.9 KB)

It contains a touch bendable cylinder I created in Blender 2.93.1: (113.4 KB)

Assuming you disable Cry Physics and recompile the Editor, you should see touchbending in action.

This is not working in my starter game with cryphys disabled.

The fact that someone has this working in 1.28 is a game changer for me though. I had never heard any confirmation.

I will try a vanilla install and disable cryphys on it then test your level when I am done with my current work objectives. I will let you know how that goes.

Thanks again for your time and effort in helping.