root-motion.patch

diff --git a/Source/Urho3D/Graphics/AnimationState.cpp b/Source/Urho3D/Graphics/AnimationState.cpp
index a6a22d16b..3d54836e9 100644
--- a/Source/Urho3D/Graphics/AnimationState.cpp
+++ b/Source/Urho3D/Graphics/AnimationState.cpp
@@ -138,7 +138,10 @@ void AnimationState::SetStartBone(Bone* startBone)
         const StringHash& nameHash = i->second_.nameHash_;
 
         if (nameHash == startBone->nameHash_)
+        {
             trackBone = startBone;
+            previousRootPosition_ = i->second_.keyFrames_.Front().position_;
+        }
         else
         {
             Node* trackBoneNode = startBone->node_->GetChild(nameHash, true);
@@ -564,6 +567,29 @@ void AnimationState::ApplyTrack(AnimationStateTrack& stateTrack, float weight, b
         }
     }
 
+    if (rootMotion_ != ARM_NONE && track->nameHash_ == startBone_->nameHash_)
+    {
+        if (lastFrame_ > frame)
+        {
+            // Handle animation wraps around.
+            previousRootPosition_ -= track->keyFrames_.Back().position_;
+        }
+
+        auto delta = newPosition - previousRootPosition_;
+        previousRootPosition_ = newPosition;
+        lastFrame_ = frame;
+
+        if (rootMotion_ == ARM_XZ)
+        {
+            const auto& nodePosition = node->GetPosition();
+            newPosition.x_ = nodePosition.x_;
+            newPosition.z_ = nodePosition.z_;
+            delta.y_ = 0;
+        }
+
+        node->GetParent()->Translate(delta * node->GetParent()->GetScale());
+    }
+
     if (silent)
     {
         if (channelMask & CHANNEL_POSITION)
diff --git a/Source/Urho3D/Graphics/AnimationState.h b/Source/Urho3D/Graphics/AnimationState.h
index 337708612..67f94e350 100644
--- a/Source/Urho3D/Graphics/AnimationState.h
+++ b/Source/Urho3D/Graphics/AnimationState.h
@@ -25,6 +25,7 @@
 #include "../Container/HashMap.h"
 #include "../Container/Ptr.h"
 #include "../Math/StringHash.h"
+#include "../Math/Vector3.h"
 
 namespace Urho3D
 {
@@ -47,6 +48,17 @@ enum AnimationBlendMode
     ABM_ADDITIVE
 };
 
+/// %Animation root motion mode.
+enum AnimationRootMotion
+{
+    /// Motion of the root bone is applied directly to that bone.
+    ARM_NONE,
+    /// XZ motion of the root bone is applied to the parent of the bone.
+    ARM_XZ,
+    /// Motion of the root bone is applied to its parent.
+    ARM_FULL,
+};
+
 /// %Animation instance per-track data.
 struct AnimationStateTrack
 {
@@ -175,6 +187,12 @@ private:
     unsigned char layer_;
     /// Blending mode.
     AnimationBlendMode blendingMode_;
+    /// Root motion state.
+    AnimationRootMotion rootMotion_{ARM_XZ};
+    /// Previous position of root bone.
+    Vector3 previousRootPosition_;
+    ///
+    unsigned lastFrame_ = 0;
 };
 
 }