From 323547bd9c2f5d70fe13bf879259606792642868 Mon Sep 17 00:00:00 2001
From: Pascal Serrarens <pascal@passervr.com>
Date: Thu, 13 Jan 2022 17:13:38 +0100
Subject: [PATCH] Improved HeadTarget.RotationX

---
 .../Scripts/Targets/HeadTarget.cs             | 30 +++++++++++++++++--
 Samples/Sites.meta                            |  8 -----
 Samples/Visitors.meta                         |  8 -----
 package.json                                  |  4 +--
 4 files changed, 30 insertions(+), 20 deletions(-)
 delete mode 100644 Samples/Sites.meta
 delete mode 100644 Samples/Visitors.meta

diff --git a/Runtime/HumanoidFree/Scripts/Targets/HeadTarget.cs b/Runtime/HumanoidFree/Scripts/Targets/HeadTarget.cs
index f80ed97..d77156e 100644
--- a/Runtime/HumanoidFree/Scripts/Targets/HeadTarget.cs
+++ b/Runtime/HumanoidFree/Scripts/Targets/HeadTarget.cs
@@ -1017,9 +1017,12 @@ namespace Passer.Humanoid {
 
         /// <summary>Sets the rotation of the head around the X axis</summary>
         public void RotationX(float angle) {
-            Vector3 angles = (Quaternion.Inverse(humanoid.transform.rotation) * transform.rotation).eulerAngles;
+            Quaternion localTargetRotation = Quaternion.Inverse(humanoid.transform.rotation) * transform.rotation;
+            GetSwingTwist(Vector3.right, localTargetRotation, out Quaternion swing, out Quaternion twist);
+
             float xAngle = angle * maxXangle;
-            transform.rotation = humanoid.transform.rotation * Quaternion.Euler(xAngle, angles.y, angles.z);
+            Quaternion newLocalTargetRotation = Quaternion.AngleAxis(xAngle, Vector3.right) * swing;
+            transform.rotation = humanoid.transform.rotation * newLocalTargetRotation;
         }
 
         /// <summary>Sets the rotation of the head around the Y axis</summary>
@@ -1029,6 +1032,29 @@ namespace Passer.Humanoid {
             transform.rotation = humanoid.transform.rotation * Quaternion.Euler(angles.x, yAngle, angles.z);
         }
 
+        public static Quaternion GetRotationAround(Vector3 axis, Quaternion rotation) {
+            Vector3 ra = new Vector3(rotation.x, rotation.y, rotation.z); // rotation axis
+            Vector3 p = Vector3.Project(ra, axis); // return projection v1 on to v2  (parallel component)
+            Quaternion twist = new Quaternion(p.x, p.y, p.z, rotation.w);
+            twist = Normalize(twist);
+            return twist;
+        }
+
+        public static Quaternion Normalize(Quaternion q) {
+            float length = Mathf.Sqrt(q.x * q.x + q.y * q.y + q.z * q.z + q.w * q.w);
+            if (length == 0)
+                return Quaternion.identity;
+
+            float scale = 1.0f / length;
+            Quaternion q1 = new Quaternion(q.x * scale, q.y * scale, q.z * scale, q.w * scale);
+            return q1;
+        }
+
+        public static void GetSwingTwist(Vector3 axis, Quaternion rotation, out Quaternion swing, out Quaternion twist) {
+            twist = GetRotationAround(axis, rotation);
+            swing = rotation * Quaternion.Inverse(twist);
+        }
+
         #endregion
 
         #region Tools
diff --git a/Samples/Sites.meta b/Samples/Sites.meta
deleted file mode 100644
index 1879ab5..0000000
--- a/Samples/Sites.meta
+++ /dev/null
@@ -1,8 +0,0 @@
-fileFormatVersion: 2
-guid: a1d84f5cb24b89d4db7c1d3b83949a69
-folderAsset: yes
-DefaultImporter:
-  externalObjects: {}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 
diff --git a/Samples/Visitors.meta b/Samples/Visitors.meta
deleted file mode 100644
index 27edab5..0000000
--- a/Samples/Visitors.meta
+++ /dev/null
@@ -1,8 +0,0 @@
-fileFormatVersion: 2
-guid: 03517ba7d9815ac47985f7ce3a768240
-folderAsset: yes
-DefaultImporter:
-  externalObjects: {}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 
diff --git a/package.json b/package.json
index c05d011..f01cbf6 100644
--- a/package.json
+++ b/package.json
@@ -24,12 +24,12 @@
 		{
 			"displayName": "Sites",
 			"description": "Example sites which can be visited with a Visitor",
-			"path": "Samples/Sites"
+			"path": "Samples~/Sites"
 		},
 		{
 			"displayName": "Visitors",
 			"description": "The default Visitors which can browse sites",
-			"path": "Samples/Visitors"
+			"path": "Samples~/Visitors"
 		}
 	]
 }
\ No newline at end of file