[Plugin] Leap Motion - Event Driven

[Deams]

1) Attach a component to your pawn/actor.

2) Use the LeapEventInterface via multiple-inheritance

I tried to add the LeapController component to a default character, but so far I can't managed to link the code.

In the Char.h I include "LeapController.h" and define a pointer to the component.

class ULeapController* LeapController;

In the Char.cpp, I instantiate the LeapController in the class constructor

ALeapCharacter::ALeapCharacter()
{
	PrimaryActorTick.bCanEverTick = true;

	LeapController = CreateDefaultSubobject<ULeapController>(TEXT("LeapControllerComponent"));
}

But end up getting the following link error:

LeapCharacter.cpp.obj : error LNK2019: unresolved external symbol "private: static class UClass * __cdecl ULeapController::GetPrivateStaticClass(wchar_t const *)" (?GetPrivateStaticClass@ULeapController@@CAPEAVUClass@@PEB_W@Z) referenced in function "public: class ULeapController * __cdecl UObject::CreateDefaultSubobject<class ULeapController>(class FName,bool)" (??$CreateDefaultSubobject@VULeapController@@@UObject@@QEAAPEAVULeapController@@VFName@@_N@Z)

Is there another step I'm forgetting about?

Edit:
It seems that adding the MinimalAPI tag for the ULeapController class fixes the compilation error to instantiate the component.

UCLASS(MinimalAPI, ClassGroup=Input, meta=(BlueprintSpawnableComponent))
class ULeapController : public UActorComponent

But the same kind of linking error happen when using a method of ULeapController.
Example when using the EnableBackgroundTracking:

LeapCharacter.cpp.obj : error LNK2019: unresolved external symbol "public: void __cdecl ULeapController::EnableBackgroundTracking(bool)" (?EnableBackgroundTracking@ULeapController@@QEAAX_N@Z) referenced in function "public: __cdecl ALeapCharacter::ALeapCharacter(void)" (??0ALeapCharacter@@QEAA@XZ)

Using the LEAPMOTION_API tag for the class definition of ULeapController does seem to export all methods.

class LEAPMOTION_API ULeapController : public UActorComponent

Is it intended?

[Deams]

Thank you for the detailed answer!
I will give it a try tonight and let you know how it goes.

[getnamo]

Hi Getnamo!

First let me thank you for all the plugins you've been sharing on github.

I was wondering if you had any idea on how I should approach translating your bp using only c++.
I mean reproducing the logic of your blueprints such as RiggedCharacter or VRController in code.
Been playing around with the plugin, but thought I would ask you directly if you'd thought about it already.

Edit:
It seems that using directly the plugin in c++ was not possible based on one of your earlier answer (#45).
Is it still the case?

Edit2:
Based on the workaround from your previous answer, I duplicated and then modified the parent of LeapBasicRiggedCharacter for a c++ character.
It does work and allow to have the c++ code of the character and the leap plugin character working in concert.
But in such an implementation, how could we access the leap info such as the hand position from the code?
Does it forces us to do everything from blueprints with the plugin?

Glad my plugins can be of use!

To access leap motion from C++, do the same thing you would do in blueprint but using the C++ methods. If you're confident you should probably use the custom approach as it will give you more direct control and flexibility which is what I'm assuming your C++ approach is about.

1) Attach a component to your pawn/actor.

2) Use the LeapEventInterface via multiple-inheritance

Now you will receive the same events you would get in blueprints, all defined in the LeapEventInterface class. Then you can follow the same instructions found at the repository readme, pay attention for example to the Example 'Debug Hand' graph on how to get basic hand information.

You have nearly complete access to the Leap API through the UE components which handle all orientation and unit conversion, but since you're in C++ you can also query the leap directly after including the necessary headers, e.g. using the pure Leap API Leap Controller

Leap::Controller leap;

See my unreal ULeapController component class for use examples.


On the topic of recreating the VRController, all it does is ensure that your camera is separated from your view controller rotation. You can follow this wiki for an example of how to do that in C++.


All the convenience characters such as RiggedCharacter are a bit more complex. What they do is contain an actor called LeapAnimBodyConnector or its subclass, which handles all the leap-specific interaction and stores it in an AnimBody data structure class. Then in the Animation Blueprint of the skeletal mesh, it looks for the AnimBody and copies its current state to the skeletal mesh, blending in animation when information is not being sent. This means the animation blueprints and characters are agnostic to the input, and the only leap specific part is the LeapAnimBodyConnector.

I haven't had the opportunity to explore how animation blueprints can be set in C++, if you find out how to do that, some guidance on it would be awesome and might help pave the way for easier skeletal mesh swapping in the future.

[Deams]

Hi Getnamo!

First let me thank you for all the plugins you've been sharing on github.

I was wondering if you had any idea on how I should approach translating your bp using only c++.
I mean reproducing the logic of your blueprints such as RiggedCharacter or VRController in code.
Been playing around with the plugin, but thought I would ask you directly if you'd thought about it already.

Edit:
It seems that using directly the plugin in c++ was not possible based on one of your earlier answer (#45).
Is it still the case?

Edit2:
Based on the workaround from your previous answer, I duplicated and then modified the parent of LeapBasicRiggedCharacter for a c++ character.
It does work and allow to have the c++ code of the character and the leap plugin character working in concert.
But in such an implementation, how could we access the leap info such as the hand position from the code?
Does it forces us to do everything from blueprints with the plugin?

[getnamo]

Hi,

I just tried 0.9.7 on MAC 10.10.4 + Leapmotion 2.3.1 + Unreal 4.9.2

But always report "Plugin 'LeapMotion' failed to load because module 'LeapMotion' does not appear to be compatible with the current version of the engine. The plugin may need to be recompiled." after I copy binaries and plugin to the project folder.

What is wrong?

BR
Caesar

0.9.7 has mac binaries synced to 4.7. Use UE4.7 or use plugin v 0.9.9 with UE4.10. Optionally add code to your project and recompile as you have source included with the plugin.

[caesarj]

Hi,

I just tried 0.9.7 on MAC 10.10.4 + Leapmotion 2.3.1 + Unreal 4.9.2

But always report "Plugin 'LeapMotion' failed to load because module 'LeapMotion' does not appear to be compatible with the current version of the engine. The plugin may need to be recompiled." after I copy binaries and plugin to the project folder.

What is wrong?

BR
Caesar

[getnamo]

Hi getnamo;

Thanks so much for your plugin. Real amazing you've been able to provide UE support unofficially. Love the echo hands, so sculptural.

I've noticed that when using the collision characters, the tracking accuracy is much worse. Without collision, seems to function better. Is that just my subjective experience or have you noticed this as well?

There may be a subjective difference betweeen the yellow character and the echo hands since the echo hands are closer to 1:1, but collision itself should not make a difference, it is literally a single toggle.

BTW Echo hands are Leap assets that I've gotten permission to release with my plugin, so praise leap for the geometry

Hello, Do you haveany update for Unreal 4.10.0? It shows this message:

[ATTACH=CONFIG]66125[/ATTACH]

In mean time I will revert to the 4.9.2

I am using OSX El Caitan 10.11.2

Update to 0.9.9
-Updated Mac binaries to 4.10

Note that mac binaries will be very rarely synced due to lack of time, so I highly urge a Mac user of the plugin to take the helm for keeping mac binaries in sync.

Edit: updated this response with 0.9.9 change

Mac is now synced to 4.10, but you have full source so you can compile the mac binary yourself at any time and make a pull request to include the binaries in the master branch for others.

[getnamo]

Update to 0.9.8
-Updated binaries to UE4.10

Image hands are still not ready atm.

Let me know if any bugs creep up!

getnamo is your plugin going to be built into one of the upcoming ue4 releases?

Not that I know of :O

mine failed, but i don't known if its because the plugin or something wrong after upgrade to Visual 2015 since i update from 2014. Haven't time for check.

edit:
compiled but i got this error on load

LogModuleManager:Warning: ModuleManager: Unable to load module 'E:/Documents/Unreal Projects/xVR2/Plugins/LeapMotion/Binaries/Win64/UE4Editor-LeapMotion.dll' because the file couldn't be loaded by the OS.

edit2:
something wrong using duplicate project, i backup my project instead of duplicate for preserve 4.9.2 files, and work fine.

binary http://s000.tinyupload.com/index.php...23592589999963

My version compiled fine without any code changes, have a go with the new release (0.9.8) to confirm if it works.

[polemos]

I'll get a 4.10 version compiled this weekend. There shouldn't be a need for code changes for 4.10 so you should be able to compile a version on your own if you want it earlier.

getnamo is your plugin going to be built into one of the upcoming ue4 releases?

[knack]

mine failed, but i don't known if its because the plugin or something wrong after upgrade to Visual 2015 since i update from 2014. Haven't time for check.

edit:
compiled but i got this error on load

LogModuleManager:Warning: ModuleManager: Unable to load module 'E:/Documents/Unreal Projects/xVR2/Plugins/LeapMotion/Binaries/Win64/UE4Editor-LeapMotion.dll' because the file couldn't be loaded by the OS.

edit2:
something wrong using duplicate project, i backup my project instead of duplicate for preserve 4.9.2 files, and work fine.

binary http://s000.tinyupload.com/index.php...23592589999963

[getnamo]

I'll get a 4.10 version compiled this weekend. There shouldn't be a need for code changes for 4.10 so you should be able to compile a version on your own if you want it earlier.

[BOBtheROSS]

I try compiled but fail, since i recently install this new version and have other problems i don't known if its a module problem. anyone compiled this module with 4.10.0?

do you have a new leap plugin from somewhere? The latest plugin on this thread is for 4.9.2.

[BOBtheROSS]

hello,
I have strange problem with the exe files on packaged Projects.
If I start the exe in the "<ProjectName>\WindowsNoEditor" folder nothing happens, the exe is active in the background (I can see in the taskmanager).
If I start the exe in the "<ProjectName>\WindowsNoEditor\<ProjectName>\Binaries\Win64" folder it starts properly.

Also I need to restart the PC before I am able to delete the exe in the "<ProjectName>\WindowsNoEditor" folder, because it's impossible to kill the process.

Is this a plugin problem or is there something that needs to be setup before the exe works properly?

[knack]

I try compiled but fail, since i recently install this new version and have other problems i don't known if its a module problem. anyone compiled this module with 4.10.0?

[Turbo Papok]

Hi guys!
Can someone build getnamo's plugin for 4.10? I have no idea how to take care of it and need it badly because of VR updates in 4.10 :/

Cheers,
j.a.