/DTrackPlugin

Native connectivity for the DTrack and DTrack2 tracking systems into the Unreal Engine 4.

Primary LanguageC++BSD 3-Clause "New" or "Revised" LicenseBSD-3-Clause

DTrackPlugin

Table of Contents

  1. About
  2. Preconditions
  3. Installation
  4. Usage
  5. -> Native C++
  6. -> Blueprint
  7. For_Developers
  8. License

About

This is a plug-in for the Unreal Engine 4.19 or later with the purpose of native integration of the Advanded Realtime Tracking DTrack and DTrack2 tracking solutions.

It enables you to use a DTrack Tracking System (i.e. ART CoCap target set or other targets) to control a virtual character inside Unreal in realtime.

Sidenotes:

It supports both Blueprint and native C++ usage. This plug-in includes the official DTrack SDK 2.4.1 in binary form. Its license is identical to this.

Preconditions

This plugin only supports the Windows 64 bit platform, due to it's precompiled DTrack SDK static library. To use it you need the Unreal Engine 4.19 or later and Microsoft Visual Studio 2015 (Express or Community Edition should suffice). Other platforms are not supported.

Installation

To use this, setup your Unreal Project as a C++ Project (This doesn't mean there needs to be only code. The project can still focus on Blueprint usage). In your project's root folder, create a directory named Plugins if it is not already there. Then clone or checkout this repository into this folder and regenerate your project. That's all.

For adding the submodule eigen:

Run "submodule update --init --recursive"

Alternatively run "git clone --recursive <project url>"

Usage

Using this functionality is generally focused on enhancing any Actor with tracking information. This can happen in either C++ or Blueprint. There's usually 3 steps involved:

  1. Add a DTrackComponent to your actor. This component will act as glue between your actor and the underlying plug-in. It also configures the plugin with the settings for your DTrack system such as server hostname or port. Please note that at this point you can only connect to one such endpoint. You can have multiple components but they must all point to the same server endpoint. Any of them will be chosen to initially setup tracking.

  2. Add the IDTrackInterface to your actor. Implementing this interface will allow you to react to the different kinds of tracking data coming in.

  3. Implement the desired events on the interface as you choose.

All translations and rotations coming in on the interface will already be tranlated in Unreal's default coordinate system und use cm as units. In order for this to work correctly the component must know about the room calibration (coordinate system) setting in your DTrack system. The property "DTrack Room Calibration" offers 3 common default settings from which you can choose:

  • Normal - Right handed with Z is up and Y is front, X to the right
  • Unreal Adapted - Right handed with Z as up and X as front
  • Powerwall - Right handed with X is right, Y as up and -Z as front (not tested yet)

Your tracking data will be treated according to this setting so it must correspond to your room calibration.

Native C++

In order to make your project depend on the plugin you may have to add the following to your module's build.cs script:

public MyProject(TargetInfo Target) {

   PublicDependencyModuleNames.AddRange(new string[] {
      "Core",
      "CoreUObject",
      ...
      "DTrackPlugin"
   });

   PrivateIncludePaths.AddRange(new string[] {
      ...
      "DTrackPlugin/Public"
   });
}

In C++ based actors you will have to add DTrackComponent to your actor as a UPROPERTY pointer and derive from the IDTrackInterface interface base. Bear in mind that your primary base (AActor in this case) must be the first in the list of base classes. Access specifiers must include write access by the Editor. This is needed so you can see and modify the component's server settings so don't omit that unless you plan on setting those in code as well. Here's how this could look like:

#include "DTrackComponent.h"
#include "DTrackInterface.h"

UCLASS()
class MYPROJECT_API AMyDTrackUsingActor : public AActor, public IDTrackInterface {

	GENERATED_BODY()
 
	public:
		...
		UPROPERTY(VisibleAnywhere, Category = DTrack)  // Choose your own property specifiers according to your needs.
		UDTrackComponent *m_dtrack_component;
            
		/// This implements the IDTrackInterface event for body tracking data coming in
		void OnBodyData_Implementation(const int32 BodyID, const FVector &Position, const FRotator &Rotation) override;

		/// This implements the IDTrackInterface event for flystick tracking data coming in
		void OnFlystickData_Implementation(const int32 FlystickID, const FVector &Position, const FRotator &Rotation) override;

		/// This implements the IDTrackInterface event for flystick tracking data coming in
		void OnFlystickButton_Implementation(const int32 FlystickID, const int32 &ButtonIndex, const bool Pressed) override;
		void OnFlystickJoystick_Implementation(const int32 FlystickID, const TArray<float> &JoystickValues);

		/// There may be more as the plug-in gains functionality. See the interface docs for details. 
}

Note the _Implementation suffixes. They are required to be able to override those interface's abstract methods. Don't omit them.

Now in your implementation file you must create the component and implement the interface functions as required. Here's how this could look like:

AMyDTrackUsingActor::AMyDTrackUsingActor() {
   ...
	m_dtrack_component = CreateDefaultSubobject<UDTrackComponent>(TEXT("DTrackComponent"));
	if (!m_dtrack_component) {
		UE_LOG(DTrack, Warning, TEXT("DTrack Component could not be created"));  // This shouldn't happen but you may treat it.
	}
}


void AMyDTrackUsingActor::OnBodyData_Implementation(const int32 BodyID, const FVector &Position, const FRotator &Rotation) {

	if (BodyID == 0) {        // The ID of the tracked body. There can be many, depending on your setup.
		FVector tmp = Position;
		tmp.X = tmp.X - 200;
		tmp.Z = tmp.Z + 200;
                             // well, do whatever you like with the data. Much flexibility here really.
		SetActorLocation(tmp, false, nullptr, ETeleportType::None);
		SetActorRotation(Rotation.Quaternion(), ETeleportType::None);
	}
}

void AMyDTrackUsingActor::OnFlystickJoystick_Implementation(const int32 FlystickID, const TArray<float> &JoystickValues) {

	FString out;  // just output those values for info.
	for (int32 i = 0; i < JoystickValues.Num(); i++) {
		out.Append(FString::Printf(TEXT(" %i: %f"), i, JoystickValues[i]));
	}

	UE_LOG(DTrack, Display, TEXT("%i joysticks - %s "), JoystickValues.Num(), *out);
}

To give some working Examples, there has been made some for Fingertracking for right hand (see: MyPoseableMesh.h) and also Body Tracking (see: MySceneComponent.h).

Before you start your game, select any actor instance of this type and go to the properties window to set your server settings.

Properties Screenshot

Blueprint

Using this in Blueprints is quite similar. Start by selecting your blueprint actor in the Editor and use Details->Add Component and select DTrack in the list. The component will appear similar to the screenshot above. The settings are also the same and you should make them point to your DTrack server.

Then open the Blueprint Editor for your actor. Select "Class Settings" and navigate to the right side of the screen to add the DTrack Interface to your actor. Use 'Add' and select DTrackInterface. Compile and save your blueprint to continue.

Blueprint_Interface Screenshot

This is equivalent to deriving from the IDTrackInterface base in your C++ actor.

Once this is done, you can implement any of the events the C++ actor could implement. To do this, go to the "Event Graph" tab and right click into the window. From the context menu select "Add Event" -> "DTrack Events" and choose which one you would like to implement. From there it's straight foward blueprint.

When using, obviously make sure the plugin is loaded and you don't accidently unload it. Also, make sure your Actor is marked as movable.

For_Developers

For Development(Architecture and Notes about Features), see the following link:

Architecture and Development Notes

Check out the Trello board to see new features, fixes and TODO's:

DTrack-Plugin Trello

TODO's:

  • Due to unity's popularity a port to it would be appreciated. But, do we really want to adapt to the engine all the time? Maybe the OpenXR standard (by Khronos Group) offers better opportunities. Standardize all of the VR devices. But due to it still being developed on that solution is not available.
  • Currently a port to OpenVR (https://github.com/ValveSoftware/openvr) is possible and viable.

For more information on it see: https://github.com/ValveSoftware/openvr/wiki/Driver-Documentation

For devices with buttons, triggers, joysticks, and other kinds of input controls, please refer to: https://github.com/ValveSoftware/openvr/wiki/IVRDriverInput-Overview

For devices that wish to provide animation data through the Skeletal Input system, please refer to: https://github.com/ValveSoftware/openvr/wiki/Creating-a-Skeletal-Input-Driver https://github.com/ValveSoftware/openvr/wiki/Hand-Skeleton

  • Request to Unreal that UPoseableMeshComponent needs a working Collision with other Meshes (static).
  • Request to Unreal that USkeletalMeshComponent needs a way to alter bone location and rotation inside the SkeletalMesh.

License

Copyright (c) 2017, Advanced Realtime Tracking GmbH All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  3. Neither the name of copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.