Picking up Objects with Vive beyond just AttachActorToComponent

[mordentral]

@yanfjz;549166

Hello, thank you so much for sharing this implementation. I’m wondering if the MotionController component is attached to the IK hands? I’m trying to use attach to to snap my MotionController pawn to my character’s hand socket, but the controller pawn will always drifted away from the hand after I move my controller. And I’d greatly appreciate it if anyone can please give me some hints.

No it uses a FABRIK node in the animation blueprint to add IK to the hands to reach for the motion controllers. It isn’t perfect but I threw it together in an hour or so to see what it felt like.

[anonymous_user_56fa0aa5]

@mordentral;549283

No it uses a FABRIK node in the animation blueprint to add IK to the hands to reach for the motion controllers. It isn’t perfect but I threw it together in an hour or so to see what it felt like.

Thank you so much! I’ll try that to see whether it works for my project

[aerloth]

Nice thread! What I’ve found out in 4.12 is if you use AttachActorToComponent and LateUpdate with controllers, the moment you detach actor from the MotionController component (resuming physics simulation) you get a funky lag/jump-in as it stops the LateUpdate.
Didn’t find the solution for this - apart from disabling LateUpdate for the MotionController, but then you get a visible lag when you compare controllers position with SteamVR overlay…

[jeffym85]

@aerloth;551959

Nice thread! What I’ve found out in 4.12 is if you use AttachActorToComponent and LateUpdate with controllers, the moment you detach actor from the MotionController component (resuming physics simulation) you get a funky lag/jump-in as it stops the LateUpdate.
Didn’t find the solution for this - apart from disabling LateUpdate for the MotionController, but then you get a visible lag when you compare controllers position with SteamVR overlay…

I can’t seem to get around this either. Has anyone found a solution? Is there a way in c++ to permanently add late update to attached actors just before detach?

[CHADALAK1]

@mordentral;540394

I made a grip plugin for the SteamVR template in here with custom MotionControllerComponents that supports better gripping mechanics. Someone was modifying it themselves for two handed grips and I don’t see why it would be that hard to achieve.

You are right, the physics constraints are lackluster because of the delay in movement (they also don’t receive render thread positional updates), the physics handle is just a managed physics constraint, it has all of the same issues, and the attachto has issues not just because of what you mentioned, but also because the engine throws out sweeping attached actors so you can’t use “EventHit” and they will pass through geometry.

The plugin originally added a sweep to all attached actors of a controller but now just has them move towards it and collects their components for the controllers late rendering thread positional updates. You could add tremor damping to it if you wanted to by modifying both the late and normal tick update positions but I honestly wouldn’t suggest it. In my opinion tremor is a necessary evil to correct tracking as things are performing as they would out of game (pick up a pen and hold it out without any tremor, I can’t).

Here is my original demo enviroment using it:

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Here is the template I made it for:
https://forums.unrealengine.com/showthread.php?106609-Steam-VR-Template

Here is the plugin itself:
https://bitbucket.org/mordentral/ue4-vr-grippable-motion-controller-plugin

I couldn’t find an immediate solution that was better than this. I do have to update it for 4.12 though, due to overriding a private class within a class acting weird in UE4 I just re-wrote the entire motion controller component so I need to pass over changes in new versions (if there are any) manually at the moment.

It has multiple styles of gripping available based on how you use it (free grip, snap, snap within radius, no collision but still hit events). Covers about all of the bases as far as I am aware, I probably should have broke it out into its own thread at some point.

How did you manage to have the bones on the arms follow with the Vive Controllers?? Is this also in the example template? If not, could you please show us a BP of the steps you did to solve this?

[ambershee]

@mordentral;542826

But if you were referencing my post where I said you couldn’t BP it with late updates I was talking about blocking held item movements and event hits not being BP possible, typical pick up is pretty straight forward with AttachTo.

How would you achieve it in 4.11, where AttachTo doesn’t exist? I’ve tried various things in the past and could never get attachment to work properly.

[mordentral]

@ambershee;574590

How would you achieve it in 4.11, where AttachTo doesn’t exist? I’ve tried various things in the past and could never get attachment to work properly.

As in VR pickups without attachment? With or without physics simulation? I’m kind of unclear about what you are asking.

My posts in here are a bit dated, I have 6 grip types implemented right now, none are Blueprint though (only BP interfaces to them) as I didn’t like some of the work arounds required to get it somewhat working in BP.

Attachment also has some downsides, more so if you want something like a two handed grip or more control over its behavior than just “follow the transform of your parent”. I don’t actually use attachment on anything for VR held items, it is all direct positional updates relative to the parent. Except for simulating objects, those are manually created kinematic physx actors and a high stiffness link to the object while forcing the late positional updates if it is not in collision at the time (late updates and physx interactions have a lot of clipping).

Edit I don’t have examples of all of the grip styles in video form but I do have an early alpha test of the physics based grip using the dynamically spawned kinematic actors. I saw that you were talking about physically interactive methods above in this thread.

https://.com/watch?v=1iy6oM_rkGQ