fix(Runtime): Add max stretch for CCDIK and update deformation

Summary:
Add a max stretch parameter for CCDIK. This will limit the amount of stretching allowed for the arm to reach the position.
Update deformation to avoid applying on shoulders. This allows for adjusting just the upper arm to hand weight independently from shoulders.

Reviewed By: sohailshafiiWk

Differential Revision: D50847609

fbshipit-source-id: 25eb753e6898f106eb7cbb9298feb163c11d46a3

Author: Andrew Kim

Runtime/Scripts/AnimationRigging/DeformationJob.cs

@@ -513,20 +513,6 @@ private void InterpolateArms(AnimationStream stream, float weight)
             var leftArmOffsetWeight = weight * LeftArmOffsetWeight.Get(stream);
             var rightArmOffsetWeight = weight * RightArmOffsetWeight.Get(stream);
 
-            if (LeftShoulderBone.IsValid(stream))
-            {
-                var leftShoulderPos = LeftShoulderBone.GetPosition(stream);
-                LeftShoulderBone.SetPosition(stream,
-                    Vector3.Lerp(_preDeformationLeftShoulderPos, leftShoulderPos, leftArmOffsetWeight));
-            }
-
-            if (RightShoulderBone.IsValid(stream))
-            {
-                var rightShoulderPos = RightShoulderBone.GetPosition(stream);
-                RightShoulderBone.SetPosition(stream,
-                    Vector3.Lerp(_preDeformationRightShoulderPos, rightShoulderPos, rightArmOffsetWeight));
-            }
-
             LeftUpperArmBone.SetPosition(stream,
                 Vector3.Lerp(_preDeformationLeftUpperArmPos, leftUpperArmPos, leftArmOffsetWeight));
             RightUpperArmBone.SetPosition(stream,

Runtime/Scripts/RetargetingProcessing/RetargetingProcessorCorrectHand.cs

@@ -49,6 +49,19 @@ public IKType HandIKType
             set => _handIKType = value;
         }
 
+        /// <summary>
+        /// The maximum stretch for the hand to reach the target position that is allowed.
+        /// </summary>
+        [Tooltip(RetargetingLayerTooltips.MaxStretch)]
+        [SerializeField]
+        private float _maxStretch = 0.01f;
+        /// <inheritdoc cref="_maxStretch" />
+        public float MaxStretch
+        {
+            get => _maxStretch;
+            set => _maxStretch = value;
+        }
+
         /// <summary>
         /// The maximum distance between the resulting position and target position that is allowed.
         /// </summary>
@@ -158,7 +171,7 @@ public override void ProcessRetargetingLayer(RetargetingLayer retargetingLayer,
                     AnimationUtilities.SolveCCDIK(_armBones, targetPosition, IKTolerance, IKIterations);
                 }
             }
-            handBone.position = targetPosition;
+            handBone.position = Vector3.MoveTowards(handBone.position, targetPosition, MaxStretch);
             handBone.rotation = handRotation;
         }
     }

Runtime/Scripts/Tooltips.cs

@@ -1215,6 +1215,9 @@ 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 MaxStretch =
+            "The maximum stretch for the hand to reach the target position that is allowed.";
+
         public const string IKTolerance =
             "The maximum distance between the resulting position and target position that is allowed.";
 

Samples/RetargetingProcessors/ArmatureCorrectLeftHand.asset

@@ -17,3 +17,4 @@ MonoBehaviour:
   _handIKType: 1
   _ikTolerance: 0.000001
   _ikIterations: 10
+  _ikMaxStretch: 0.01

Samples/RetargetingProcessors/ArmatureCorrectRightHand.asset

@@ -17,3 +17,4 @@ MonoBehaviour:
   _handIKType: 1
   _ikTolerance: 0.000001
   _ikIterations: 10
+  _ikMaxStretch: 0.01