From 00715f1906d95d4a56450bb12b3c20c7c6316522 Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Wed, 27 Jan 2016 10:14:37 -0800
Subject: [PATCH] apply "hips offset" to root of state graph

(Somemtimes the hips are not the root.
I'm looking at YOU blender!)
---
 libraries/animation/src/AnimInverseKinematics.cpp | 13 +++++++++++--
 libraries/animation/src/AnimInverseKinematics.h   |  9 +++++----
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/libraries/animation/src/AnimInverseKinematics.cpp b/libraries/animation/src/AnimInverseKinematics.cpp
index e47a12960e..d7c604fff1 100644
--- a/libraries/animation/src/AnimInverseKinematics.cpp
+++ b/libraries/animation/src/AnimInverseKinematics.cpp
@@ -376,13 +376,13 @@ const AnimPoseVec& AnimInverseKinematics::overlay(const AnimVariantMap& animVars
                 ++constraintItr;
             }
         } else {
-            // shift the hips according to the offset from the previous frame
+            // shift the everything according to the _hipsOffset from the previous frame
             float offsetLength = glm::length(_hipsOffset);
             const float MIN_HIPS_OFFSET_LENGTH = 0.03f;
             if (offsetLength > MIN_HIPS_OFFSET_LENGTH) {
                 // but only if offset is long enough
                 float scaleFactor = ((offsetLength - MIN_HIPS_OFFSET_LENGTH) / offsetLength);
-                _relativePoses[_hipsIndex].trans = underPoses[_hipsIndex].trans + scaleFactor * _hipsOffset;
+                _relativePoses[_rootIndex].trans = underPoses[_rootIndex].trans + scaleFactor * _hipsOffset;
             }
 
             solveWithCyclicCoordinateDescent(targets);
@@ -775,9 +775,18 @@ void AnimInverseKinematics::setSkeletonInternal(AnimSkeleton::ConstPointer skele
         initConstraints();
         _headIndex = _skeleton->nameToJointIndex("Head");
         _hipsIndex = _skeleton->nameToJointIndex("Hips");
+
+        // walk up the hierarchy until we find the root and cache its index
+        _rootIndex = _hipsIndex;
+        int parentIndex = _skeleton->getParentIndex(_hipsIndex);
+        while (parentIndex != -1) {
+            _rootIndex = parentIndex;
+            parentIndex = _skeleton->getParentIndex(_rootIndex);
+        }
     } else {
         clearConstraints();
         _headIndex = -1;
         _hipsIndex = -1;
+        _rootIndex = -1;
     }
 }
diff --git a/libraries/animation/src/AnimInverseKinematics.h b/libraries/animation/src/AnimInverseKinematics.h
index 971d2d5ff1..52dd4b5863 100644
--- a/libraries/animation/src/AnimInverseKinematics.h
+++ b/libraries/animation/src/AnimInverseKinematics.h
@@ -79,13 +79,14 @@ protected:
     AnimPoseVec _relativePoses; // current relative poses
 
     // experimental data for moving hips during IK
-    int _headIndex = -1;
-    int _hipsIndex = -1;
-    glm::vec3 _hipsOffset = Vectors::ZERO;
+    glm::vec3 _hipsOffset { Vectors::ZERO };
+    int _headIndex { -1 };
+    int _hipsIndex { -1 };
+    int _rootIndex { -1 };
 
     // _maxTargetIndex is tracked to help optimize the recalculation of absolute poses
     // during the the cyclic coordinate descent algorithm
-    int _maxTargetIndex = 0;
+    int _maxTargetIndex { 0 };
 };
 
 #endif // hifi_AnimInverseKinematics_h