feat(Runtime): Add an option for using world hand position as the target

Summary: In cases where the character is scaled, the world hand position might be desired. This adds an option for that capability.

Reviewed By: sohailshafiiWk

Differential Revision: D53066093

fbshipit-source-id: 3be58db233496ed93bd64a7e6a4fa6bf50cffaca

Author: Andrew Kim

Runtime/Scripts/AnimationRigging/RiggingUtilities.cs

@@ -118,19 +118,24 @@ public static bool IsFiniteVector3(Vector3 v)
         }
 
         /// <summary>
-        /// Returns the result of diving a Vector3 by another Vector3.
+        /// Returns the result of dividing a Vector3 by another Vector3.
         /// </summary>
         /// <param name="dividend">The Vector3 dividend.</param>
         /// <param name="divisor">The Vector3 divisor.</param>
         /// <returns>The divided Vector3.</returns>
         public static Vector3 DivideVector3(Vector3 dividend, Vector3 divisor)
         {
-            Vector3 targetScale = Vector3.one;
+            Vector3 targetScale;
             if (Vector3IsNonZero(divisor))
             {
                 targetScale = new Vector3(
                     dividend.x / divisor.x, dividend.y / divisor.y, dividend.z / divisor.z);
             }
+            else
+            {
+                Debug.LogError("Zero detected inside divisor. Returning dividend.");
+                return dividend;
+            }
 
             return targetScale;
         }

Runtime/Scripts/RetargetingProcessing/RetargetingProcessorCorrectHand.cs

@@ -49,6 +49,16 @@ public IKType HandIKType
             set => _handIKType = value;
         }
 
+        [Tooltip(RetargetingLayerTooltips.UseWorldHandPosition)]
+        [SerializeField]
+        private bool _useWorldHandPosition = true;
+        /// <inheritdoc cref="_useWorldHandPosition" />
+        public bool UseWorldHandPosition
+        {
+            get => _useWorldHandPosition;
+            set => _useWorldHandPosition = value;
+        }
+
         /// <summary>
         /// The maximum stretch for the hand to reach the target position that is allowed.
         /// </summary>
@@ -157,6 +167,11 @@ public override void PrepareRetargetingProcessor(RetargetingLayer retargetingLay
         /// <inheritdoc />
         public override void ProcessRetargetingLayer(RetargetingLayer retargetingLayer, IList<OVRBone> ovrBones)
         {
+            if (Weight < float.Epsilon)
+            {
+                return;
+            }
+
             var isFullBody = retargetingLayer.GetSkeletonType() == OVRSkeleton.SkeletonType.FullBody;
             var leftHandWristIndex = isFullBody ? (int)OVRSkeleton.BoneId.FullBody_LeftHandWrist :
                 (int)OVRSkeleton.BoneId.Body_LeftHandWrist;
@@ -179,10 +194,17 @@ public override void ProcessRetargetingLayer(RetargetingLayer retargetingLayer,
                 return;
             }
 
+            var targetHandPosition = targetHand.position;
+            if (_useWorldHandPosition)
+            {
+                var localScale = retargetingLayer.transform.localScale;
+                targetHandPosition = RiggingUtilities.DivideVector3(targetHandPosition, localScale);
+            }
+
             var handBone = _armBones[0];
             handBone.position = _originalHandPosition;
             var handRotation = handBone.rotation;
-            Vector3 targetPosition = Vector3.Lerp(handBone.position, targetHand.position, Weight);
+            Vector3 targetPosition = Vector3.Lerp(handBone.position, targetHandPosition, Weight);
             bool solvedIK = false;
             if (Weight > 0.0f)
             {

Runtime/Scripts/Tooltips.cs

@@ -1306,6 +1306,9 @@ public static class RetargetingLayerTooltips
             "The type of IK that should be applied to modify the arm bones toward the " +
             "correct hand target.";
 
+        public const string UseWorldHandPosition =
+            "If true, use the world hand position for placing the hand instead of the scaled position.";
+
         public const string MaxHandStretch =
             "The maximum stretch for the hand to reach the target position that is allowed.";