Official UE4 Plugin

[AlexColgan]

With the release of Unreal Engine 4.7, Epic and Leap Motion have joined forces to create an official plugin! This introductory Windows plugin enables developers to quickly and easily add virtual hands to their games.

Right now, the plugin is available exclusively through the UE4 source code. Follow the steps in our documentation to access Unreal’s GitHub repository. From there, you can download the source code, build it, and start creating an amazing experience for desktop or VR! Learn more on our blog post: blog.leapmotion.com/introducing-the-leap-motion-plugin-for-ue4

Unreal 4.7 Source + Plugin: unrealengine.com/ue4-on-github
Integration Page: developer.leapmotion.com/gallery/tags/ue4
Plugin Documentation: developer.leapmotion.com/documentation/unreal/index.html

Share your projects on the Unreal forum:
forums.unrealengine.com/forumdisplay.php?11-Work-in-Progress

Questions? Feature requests? Post in this thread, or jump over to the official Unreal thread:
forums.unrealengine.com/showthread.php?59865-Official-Leap-Motion-Plugin!&p=227875#post227875

[AlexColgan]

Hi everyone,

Just a quick update on the official Unreal Engine plugin. With the recent release of Unreal 4.8, we encountered a bug that causes hand jittering effects in demos. This issue has since been resolved, but only on the Master branch of Epic’s GitHub project for Unreal Engine. (Specifically, this commit, which you can see if you have access to Epic’s repository.)

That means there are three possible approaches you can take:

• Continue building on Unreal 4.7. This issue only affects the very latest version of Unreal, so if you have a project in Unreal 4.7, build away!
• Compile Unreal 4.8 from the Master branch. It’s very important to note that the hotfix is located in the Master branch, rather than the 4.8 branch.
• Cherry-pick the fix to your local branch. This is the best approach to avoid possible stability issues.

In all three cases, be sure to follow the very latest instructions on our Unreal documentation to access Unreal’s GitHub repository and enable the plugin.

We’re working hard with Epic to get these issues fully resolved -- and the plugin made available in the installed version of the engine! -- in time for Unreal Engine 4.9. Thanks so much for your patience and support.

[malcriado]

So, Alex..could you explain in plain english what do you mean by "Cherry-pick the fix to your local branch". Thanks in advance.
F.

[rtuisku]

@malcriado Thanks for asking. With Cherry-picking we mean the GIT command (that you can possibly also do in your editor). For cherry-picking a specific commit, you need the SHA1 of the commit that Alex linked, here: https://github.com/EpicGames/UnrealEngine/commit/635fa36af551e8258ad96adcb437c1519b9df35f

Follow these steps if you're using git on the command line:

1. Go to your local branch using git checkout my-branch-name where my-branch-name is the branch in your git clone of Unreal Engine 4 source.
2. Run: git cherry-pick 635fa36af551e8258ad96adcb437c1519b9df35f
3. Rebuild and you're done.

More information about Git SCM and cherry-picking can be found from its documention: http://git-scm.com/docs/git-cherry-pick

[malcriado]

Sorry for bothering again, but since i´m used to install ue in the traditional way, and not compiling it gets difficult to understand the right method to get leap motion in the correct way.
what i´ve done so far is download the "master branch" from github and now i´m running setup.bat and checking for dependencies...am i following the right path? thanks again!

[katem]

@malcriado Sounds like you're on the right path. Next step will be opening the .sln in visual studio and building the Unreal Engine.

[malcriado]

well, once again, after downloaded the master branch and run the setup.bat got nothing as a result. Just a folder.
@katem looked for the sln file (which name is...), making a find inside the folder and found tons of files with that extension.
Leap Motion or Epic people should have to do a step by step guide for non programmers humans that want to use leap motion in ue4, not every user is a programmer .
Thanks again.

[katem]

@malcriado Our Dev Portal docs are geared toward a developer crowd, but I'm going to PM you some additional step by step instructions that might be more palatable.

[Ayfel]

Can I get those step by step as well? Thanks!

[katem]

Hey there -- absolutely. Sent.

[malcriado]

Hi Katem, already doing your step by step installation, first time did not work so im redoing everything from scracth again.
By the way UE 4.8.2 is already out there and would have been be nice if this fix was added to that hotfix.
Thanks again.
F.

[vimaxus]

Will Image Hand come to the official ue4 plugin soon? maybe in time for ue4?

I started to mod getnamo's plugin to outcrop the hands in each corrected image but having depth information would be a big plus as the mix between 4cm and the oculus IPD as well as the depth difference is not optimal... Maybe share the unity implementation?

[katem]

It's definitely something we'd like to implement. Stay tuned for developments down the line on this front.

[Joe_Ward]

Note that Unreal Engine branch 4.9 is available. This means that you can build directly from branch 4.9 rather then following the steps we outlined above. Once Epic releases version 4.9, you should no longer have to build from source at all.

---

That means there are three possible approaches you can take:

Continue building on Unreal 4.7. This issue only affects the very latest version of Unreal, so if you have a project in Unreal 4.7, build away!

Compile Unreal 4.8 from the Master branch. It’s very important to note that the hotfix is located in the Master branch, rather than the 4.8 branch.

Cherry-pick the fix to your local branch. This is the best approach to avoid possible stability issues.

[TheDramatic]

Just getting started with your plugin in UE4.9.

The Demos are nice and working (except for excessive left rigged hand flickering).

As far as I understand the position coordinates are already calculated into UE world coordinates.

Is there a tutorial or doc how I can map those to a third person char?

If that is possible (with customController I think), how can I blend it with an animation?

Example:
Character with hands following leap motion jumps. The Jump animation is played (including handscoords). On every tick leapmotion coords are applied to hands as well.

Is that case handled?
Is it possible to blend both animations (realtime for hands, mocap for other bones)?

What would happen if the character is e.g. flying in horizontal position. How does the plugins controller behave?

Thanks in advance.

[Joe_Ward]

I think the LeapCharacterExample in the "Demo Pack" is the closest to a third person controller example -- the main difference between first person and 3rd is the position of the camera. As far as connecting the hand data to a rigged skeleton, the RiggedHand Demo is the best place to look. I think the trickiest part is matching the orientation of the bone or joint that connects the parts of the model driven entirely by normal animation and the part driven with the Leap Motion tracking data. Getnamo's plugin, frankly, has more to offer here than our plugin, currently.

Beyond that, to drive part of a character animation with blended animation loops and InverseKinematics looks possible. The following Unreal documentation covers one approach:
https://docs.unrealengine.com/latest/INT/Engine/Animation/PhysicallyDrivenAnimation/index.html

For flying or other horizontal posture, I don't think that you could literally have the player lift their hands over their head in the superman-flying-posture -- in a desktop app their hands would be out of range and in a VR app it would be tiring and unnatural. If you are driving the hands of a character with the tracking data, then you would probably have to apply a transform to the tracking data so that the player could maintain a comfortable, natural hand position.

In general, the plugin controller doesn't know anything about your character or animation. It just supplies the data transformed into the Unreal world space.

[procons]

Hi,
does the LeapMotion Plugin has any requirements to DirectX9 on Windows 8? We couldn't run our scene (UE 4,7 / 4.8) with the plugin on a windows 8 machine without installing directx9.
Bests

[AlexColgan]

The UE4 plugin is now a part of the Unreal Engine 4.9 Preview -- no source code compiling required! Learn more in this thread: https://community.leapmotion.com/t/leap-motion-unreal-4-9/3534/1

[pshtif]

So the 3D Jam is almost upon us and the problem with the UE4 examples is still not solved since the HMD mode doesn't work. Is this something that will be solved before the Jam?

[shwetamazumder27]

hi , I have intalled leap motion plugin in unreal engine 4.7 successfully but why I can't see my hand on screen while running a game?