From 3434d1f1e73fc32282d0e951a03c669471efe6ff Mon Sep 17 00:00:00 2001
From: MattGray <matt.gray@ultraleap.com>
Date: Fri, 3 Nov 2023 17:25:43 +0000
Subject: [PATCH 1/2] address thumb and wrist rotation issues for xrhands

---
 .../XRHandsSubsystem/LeapHandsSubsystem.cs    | 37 ++++++++++++++-----
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs b/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs
index c52df3ec9d..c5475f7784 100644
--- a/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs
+++ b/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs
@@ -157,7 +157,7 @@ bool PopulateXRHandFromLeap(Hand leapHand, ref Pose rootPose, ref NativeArray<XR
             }
 
             Pose palmPose = CalculatePalmPose(leapHand);
-            Pose wristPose = CalculateWristPose(leapHand);
+            Pose wristPose = CalculateWristPose(leapHand, palmPose.position);
 
             rootPose = wristPose;
             Handedness handedness = (Handedness)((int)leapHand.GetChirality() + 1); // +1 as unity has "invalid" handedness while we do not
@@ -181,14 +181,32 @@ bool PopulateXRHandFromLeap(Hand leapHand, ref Pose rootPose, ref NativeArray<XR
                     {
                         var bone = finger.bones[i];
 
-                        handJoints[jointIndex] = XRHandProviderUtility.CreateJoint(handedness,
-                            XRHandJointTrackingState.Pose,
-                            XRHandJointIDUtility.FromIndex(jointIndex),
-                            new Pose(bone.PrevJoint, bone.Rotation));
+                        if (i == 1)
+                        {
+                            // Rotate the first joint of the thumb to better suit the OpenXR spec
+                            Quaternion rot = bone.Rotation * Quaternion.Euler(0,
+                                leapHand.IsLeft ? 25.9f : -25.9f,
+                                leapHand.IsLeft ? -50f : 50f);
+
+                            handJoints[jointIndex] = XRHandProviderUtility.CreateJoint(handedness,
+                                                        XRHandJointTrackingState.Pose,
+                                                        XRHandJointIDUtility.FromIndex(jointIndex),
+                                                        new Pose(bone.PrevJoint, rot));
+                        }
+                        else
+                        {
+                            handJoints[jointIndex] = XRHandProviderUtility.CreateJoint(handedness,
+                                                        XRHandJointTrackingState.Pose,
+                                                        XRHandJointIDUtility.FromIndex(jointIndex),
+                                                        new Pose(bone.PrevJoint, bone.Rotation));
+                        }
+
+
                         jointIndex++;
                     }
 
                     var distal = finger.Bone(Bone.BoneType.TYPE_DISTAL);
+
                     handJoints[jointIndex] = XRHandProviderUtility.CreateJoint(handedness,
                         XRHandJointTrackingState.Pose,
                         XRHandJointIDUtility.FromIndex(jointIndex),
@@ -229,14 +247,13 @@ Pose CalculatePalmPose(Hand leapHand)
             return palmPose;
         }
 
-        Pose CalculateWristPose(Hand leapHand)
+        Pose CalculateWristPose(Hand leapHand, Vector3 newPalmPos)
         {
-            Vector3 wristUp = leapHand.GetMiddle().Bone(Bone.BoneType.TYPE_METACARPAL).Rotation * Vector3.up;
-            Vector3 wristForward = leapHand.GetMiddle().Bone(Bone.BoneType.TYPE_METACARPAL).PrevJoint - leapHand.WristPosition;
+            Vector3 palmToWrist = leapHand.WristPosition - leapHand.PalmPosition;
 
             Pose wristPose = new Pose();
-            wristPose.position = leapHand.WristPosition;
-            wristPose.rotation = Quaternion.LookRotation(wristForward, wristUp);
+            wristPose.position = newPalmPos + palmToWrist;
+            wristPose.rotation = leapHand.Rotation;
 
             return wristPose;
         }

From 7fce67331c6e961049749f99dd2afe2d14e7035b Mon Sep 17 00:00:00 2001
From: MattGrayUL <60962475+MattGrayUL@users.noreply.github.com>
Date: Fri, 3 Nov 2023 17:45:19 +0000
Subject: [PATCH 2/2] Update LeapHandsSubsystem.cs

---
 .../Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs    | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs b/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs
index c5475f7784..d8c708c578 100644
--- a/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs
+++ b/Packages/Tracking/Core/Runtime/Scripts/XRHandsSubsystem/LeapHandsSubsystem.cs
@@ -186,7 +186,7 @@ bool PopulateXRHandFromLeap(Hand leapHand, ref Pose rootPose, ref NativeArray<XR
                             // Rotate the first joint of the thumb to better suit the OpenXR spec
                             Quaternion rot = bone.Rotation * Quaternion.Euler(0,
                                 leapHand.IsLeft ? 25.9f : -25.9f,
-                                leapHand.IsLeft ? -50f : 50f);
+                                leapHand.IsLeft ? -63.45f : 63.45f);
 
                             handJoints[jointIndex] = XRHandProviderUtility.CreateJoint(handedness,
                                                         XRHandJointTrackingState.Pose,
@@ -302,4 +302,4 @@ static bool DoesDescriptorExist()
 public class LeapHandsSubsystem : XRHandSubsystem
 {
 
-}
\ No newline at end of file
+}