From fb5c45f4742c5ca132b464ee80d96dad900441c4 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Thu, 13 May 2021 14:41:43 +0200
Subject: [PATCH] Add `SetMasterPoseModel` to Animated Model for modular
 characters

---
 Source/Engine/Content/Assets/SkinnedModel.h  |  2 --
 Source/Engine/Level/Actors/AnimatedModel.cpp | 27 ++++++++++++++++++--
 Source/Engine/Level/Actors/AnimatedModel.h   |  7 +++++
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/Source/Engine/Content/Assets/SkinnedModel.h b/Source/Engine/Content/Assets/SkinnedModel.h
index d2d6eba96..08cbf23b0 100644
--- a/Source/Engine/Content/Assets/SkinnedModel.h
+++ b/Source/Engine/Content/Assets/SkinnedModel.h
@@ -64,7 +64,6 @@ public:
     /// <summary>
     /// Gets the amount of loaded model LODs.
     /// </summary>
-    /// <returns>Loaded LODs count</returns>
     API_PROPERTY() FORCE_INLINE int32 GetLoadedLODs() const
     {
         return _loadedLODs;
@@ -93,7 +92,6 @@ public:
     /// <summary>
     /// Gets index of the highest resident LOD (may be equal to LODs.Count if no LOD has been uploaded). Note: LOD=0 is the highest (top quality)
     /// </summary>
-    /// <returns>LOD index</returns>
     FORCE_INLINE int32 HighestResidentLODIndex() const
     {
         return GetLODsCount() - _loadedLODs;
diff --git a/Source/Engine/Level/Actors/AnimatedModel.cpp b/Source/Engine/Level/Actors/AnimatedModel.cpp
index a1a9d6db6..a62aad592 100644
--- a/Source/Engine/Level/Actors/AnimatedModel.cpp
+++ b/Source/Engine/Level/Actors/AnimatedModel.cpp
@@ -44,7 +44,8 @@ void AnimatedModel::UpdateAnimation()
         || !IsActiveInHierarchy()
         || SkinnedModel == nullptr
         || !SkinnedModel->IsLoaded()
-        || _lastUpdateFrame == Engine::FrameCount)
+        || _lastUpdateFrame == Engine::FrameCount
+        || _masterPose)
         return;
     _lastUpdateFrame = Engine::FrameCount;
 
@@ -183,6 +184,17 @@ int32 AnimatedModel::FindClosestNode(const Vector3& location, bool worldSpace) c
     return result;
 }
 
+void AnimatedModel::SetMasterPoseModel(AnimatedModel* masterPose)
+{
+    if (masterPose == _masterPose)
+        return;
+    if (_masterPose)
+        _masterPose->AnimationUpdated.Unbind<AnimatedModel, &AnimatedModel::OnAnimationUpdated>(this);
+    _masterPose = masterPose;
+    if (_masterPose)
+        _masterPose->AnimationUpdated.Bind<AnimatedModel, &AnimatedModel::OnAnimationUpdated>(this);
+}
+
 #define CHECK_ANIM_GRAPH_PARAM_ACCESS() \
     if (!AnimationGraph) \
     { \
@@ -378,6 +390,7 @@ void AnimatedModel::BeginPlay(SceneBeginData* data)
 void AnimatedModel::EndPlay()
 {
     AnimationManager::RemoveFromUpdate(this);
+    SetMasterPoseModel(nullptr);
 
     // Base
     ModelInstanceActor::EndPlay();
@@ -443,11 +456,21 @@ void AnimatedModel::UpdateBounds()
 void AnimatedModel::OnAnimationUpdated()
 {
     ANIM_GRAPH_PROFILE_EVENT("OnAnimationUpdated");
+    auto& skeleton = SkinnedModel->Skeleton;
+
+    // Copy pose from the master
+    if (_masterPose && _masterPose->SkinnedModel->Skeleton.Nodes.Count() == skeleton.Nodes.Count())
+    {
+        ANIM_GRAPH_PROFILE_EVENT("Copy Master Pose");
+        const auto& masterInstance = _masterPose->GraphInstance;
+        GraphInstance.NodesPose = masterInstance.NodesPose;
+        GraphInstance.RootTransform = masterInstance.RootTransform;
+        GraphInstance.RootMotion = masterInstance.RootMotion;
+    }
 
     // Calculate the final bones transformations and update skinning
     {
         ANIM_GRAPH_PROFILE_EVENT("Final Pose");
-        auto& skeleton = SkinnedModel->Skeleton;
         UpdateBones.Resize(skeleton.Bones.Count(), false);
         for (int32 boneIndex = 0; boneIndex < skeleton.Bones.Count(); boneIndex++)
         {
diff --git a/Source/Engine/Level/Actors/AnimatedModel.h b/Source/Engine/Level/Actors/AnimatedModel.h
index 6317e280c..df218b897 100644
--- a/Source/Engine/Level/Actors/AnimatedModel.h
+++ b/Source/Engine/Level/Actors/AnimatedModel.h
@@ -65,6 +65,7 @@ private:
     float _lastMinDstSqr;
     uint64 _lastUpdateFrame;
     BlendShapesInstance _blendShapes;
+    ScriptingObjectReference<AnimatedModel> _masterPose;
 
 public:
 
@@ -224,6 +225,12 @@ public:
     /// <returns>The zero-based index of the found node. Returns -1 if skeleton is missing.</returns>
     API_FUNCTION() int32 FindClosestNode(const Vector3& location, bool worldSpace = false) const;
 
+    /// <summary>
+    /// Sets the master pose model that will be used to copy the skeleton nodes animation. Useful for modular characters.
+    /// </summary>
+    /// <param name="masterPose">The master pose actor to use.</param>
+    API_FUNCTION() void SetMasterPoseModel(AnimatedModel* masterPose);
+
 public:
 
     /// <summary>