How to integrate the Leap Motion SDK V2 with the Oculus Rift DK2 in Unity for hand skeleton tracking, object hand interaction and player movement using the Rift's positional tracker.

1. Oculus Rift DK2 + Leap
Motion Unity Tutorial
Chris Zaharia @chrisjz

2. Content
• Leap Motion VR
• Hand tracking using Leap
SDK V2 (Skeletal Tracking)
• Object interaction
• Movement using Rift DK2
positional tracking

3. Leap Motion SDK V2
•Currently in beta
•Introduces skeletal tracking

4. Leap Motion VR

5. Augmented Reality
• Image API
• Infrared & Night Vision
• Enable in Leap Motion Control Panel > Settings > General > Allow
Images
• Leap Oculus Passthrough Unity Package
• Next Leap Motion may have colour camera

6. Requirements
• IDE
• Unity Pro
• Leap
• Leap Motion Driver
• Leap Motion V2 Tracking Beta (v.2.1.1.21671+)
• Leap Motion V2 Skeletal Assets (beta)
• Rift DK2
• Unity 4 Pro Integration

7. Scope
•Map physical hand and finger movements to 3D hand
model and physics
• Grab physics objects (rigidbodies) by pinching
• Movement and jump using DK2’s positional tracker

8. Leap Motion - Unity File Structure
• LeapMotion
• Materials
• Blinn2.mat
• Gloves.mat
• Hands_Alt_blinn1.mat
• Models
• HandsRealistic.fbx
• Prefabs
• Hand Graphics
• RigidLeftHand.prefab
• RigidRightHand.prefab
• Hand Physics
• ThickRigidHand.prefab
• HandController.prefab

9. • LeapMotion
• …
• Scripts
• Hand
• FingerModel.cs
• HandModel.cs
• RiggedFinger.cs
• RiggedHand.cs
• RigidFinder.cs
• RigidHand.cs
• SkeletalFinger.cs
• SkeletalHand.cs
• Tools
• ToolModel.cs
• Utils
• LeapRecorder.cs
• LeapUnityExtensions.cs
• MagneticPinch.cs
• HandController.cs

10. • Plugins
• [Include all files]

11. Attach hands to player
• Assumed that you’ve already integrated Rift with player
• Is compatible with Sixense’s Razer Hydra integration via script (see
LeapHandExtendController.cs in tutorial)

12. 1. Create empty GameObject called “LeapHandController” and place
under OvrCameraController.
2. Either attach the HandController prefab to game object or attach
HandController.cs script.
3. Fill out variables with the following:

13. Setup RigidLeftHand + RigidRightHand prefabs
• Check if both prefabs are set as follows or change
accordingly.
MagneticPinch.cs script allows user to
grab rigidbodies by pinching fingers

14. For right hand, choose
the [..]Arm3 mesh
Each finger must have the following variables,
based on type of finger (i.e. index, pinky) and if
it’s left (starts with L) or right (starts with R):

15. Setup ThickRigidHand prefab
• Gives the hand collisions and
physics
• Can therefore push objects

16. Magnetic Pinch Script
• Allows user to grab closest object which has a rigidbody
• Force Spring Constant sets the elasticity of the grip to object
• Magnetic Distance determines how close an object must be from a
hand for it to be grabbed
Warning: There is a conflict between Magnetic
Pinch and enabling the Left/Right Physics
Models. You’d need to fix this conflict by making
the magnetic script ignore the hand’s physics

17. Grab Hand and Grabbable scripts
• As an alternative to Magnetic Pinch script
• Assign GrabHand.cs to hand graphic prefab
• Assign Grabbable.cs to rigidbody object to be grabbed

18. Hand Physics
• Interact with objects in a realistic way
• Grab small objects with one hand
• Grab larger objects with multiple hands
• Push/Pull other objects
• Other possibilities
• Grabbable objects must have colliders
Currently, grasping objects with hands is still
quite jittery. Future SDK or Leap hardware
updates should improve on this hopefully.

20. Handle conflicts with other hand trackers
• This approach will hide/disable Sixense hands if leap motion detects
leap hands in scene
• Start by extending Leap Motion’s HandController.cs

21. LeapHandExtendController.cs (1)
using UnityEngine;
using System.Collections;
using Leap;
public class LeapHandExtendController : HandController {
protected Controller leap_controller_;
protected void Awake () {
leap_controller_ = new Controller();
}

22. LeapHandExtendController.cs (2)
protected void LateUpdate () {
if (leap_controller_ == null)
return;
CheckIfHandsEnabled ();
}

23. LeapHandExtendController.cs (3)
protected void CheckIfHandsEnabled () {
Frame frame = leap_controller_.Frame();
HandList hands = frame.Hands;
int num_hands = hands.Count;
if (num_hands > 0) {
TriggerSixenseHands (false);
} else {
TriggerSixenseHands (true);
}
}

24. Movement - DK2 Positional Tracking
• Move/Jump by using DK2’s positional tracking
• Move forward or backward by moving head in those directions
• Either rotate or strafe sideways by moving head left/right
• Jump by popping head upwards
• Could crouch too by popping head downwards
• User should normally be positioned directly in front of DK2’s tracker

25. Logic - Positional Tracking Movement
• Create/modify your player input controller script, attached to player
• Head position is calculated by subtracting the initial local position of the
main camera, of when scene is loaded, from its current position
• Create configurable Vector3 variables for:
• Sensitivity – strength multiplier of movement or jump actions
• Minimum – The minimum position that the Rift must be away from the centre
position, for the action to actually be triggered
• Movement will use the X (-left/+right) and Z axis (+forward/-backward) in
the direction of the camera as a variable sent to the Character Motor’s
inputMoveDirection variable
• Jump will use the Y axis and will be mapped to the Character Motor’s
inputJump variable

27. Code – Positional Track Movement
[RequireComponent(typeof(CharacterMotor))]
public class FPSInputController : MonoBehaviour {
…
public bool ovrMovement = false; // Enable move player by moving head on X and Z axis
public bool ovrJump = false; // Enable player jumps by moving head on Y axis upwa rds
public Vector3 ovrControlSensitivity = new Vector3(1, 1, 1); // Multiplier of positiona tracking move/jump actions
public Vector3 ovrControlMinimum = new Vector3(0, 0, 0); // Min distance of head from centre to move/jump
public enum OvrXAxisAction { Strafe = 0, Rotate = 1 }
public OvrXAxisAction ovrXAxisAction = OvrXAxisAction.Rotate; // Whether x axis positional tracking performs strafing or rotation
private GameObject mainCamera; // Camera where movement orientation is done and audio listener enabled
private CharacterMotor motor;
// OVR positional tracking, currently works via tilting head
private Vector3 initPosTrackDir;
private Vector3 curPosTrackDir;
private Vector3 diffPosTrackDir;

28. Start + Update
void Start() {
…
initPosTrackDir = mainCamera.transform.localPosition;
}
void Update() {
// Get the input vector from OVR positional tracking
if (ovrMovement || ovrJump) {
curPosTrackDir = mainCamera.transform.localPosition;
diffPosTrackDir = curPosTrackDir - initPosTrackDir;
}

29. Update (continued)
…
if (ovrMovement) {
if (diffPosTrackDir.x <= -ovrControlMinimum.x || diffPosTrackDir.x >= ovrControlMinimum.x) {
if (ovrXAxisAction == OvrXAxisAction.Strafe) {
diffPosTrackDir.x *= ovrControlSensitivity.x;
} else {
transform.Rotate(0, diffPosTrackDir.x * ovrControlSensitivity.x, 0);
diffPosTrackDir.x = 0;
}
} else {
diffPosTrackDir.x = 0;
}

30. Update (continued)
…
if (diffPosTrackDir.z <= -ovrControlMinimum.z || diffPosTrackDir.z >= ovrControlMinimum.z) {
diffPosTrackDir.z *= ovrControlSensitivity.z;
} else {
diffPosTrackDir.z = 0;
}
directionVector = new Vector3(diffPosTrackDir.x, 0, diffPosTrackDir.z);
}

31. Update (continued)
if (ovrJump) {
if (diffPosTrackDir.y > ovrControlMinimum.y) {
motor.inputJump = true;
} else {
motor.inputJump = false;
}
} else {
motor.inputJump = Input.GetButton ("Jump");
}
…
motor.inputMoveDirection = mainCamera.transform.rotation * directionVector; // performs actual movement

32. }