From c5d3954bc8102867d3ffda3f145f2333f1f292a3 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Sat, 4 Nov 2023 20:32:52 +0100
Subject: [PATCH] Add `CalculateBoneOffsetMatrices` option to fix some animated
 model skeletons rendering

#1862
---
 Source/Engine/Tools/ModelTool/ModelTool.cpp | 20 +++++++++++---------
 Source/Engine/Tools/ModelTool/ModelTool.h   |  3 +++
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/Source/Engine/Tools/ModelTool/ModelTool.cpp b/Source/Engine/Tools/ModelTool/ModelTool.cpp
index 116f63407..9954db2c3 100644
--- a/Source/Engine/Tools/ModelTool/ModelTool.cpp
+++ b/Source/Engine/Tools/ModelTool/ModelTool.cpp
@@ -367,6 +367,7 @@ void ModelTool::Options::Serialize(SerializeStream& stream, const void* otherObj
     SERIALIZE(ImportLODs);
     SERIALIZE(ImportVertexColors);
     SERIALIZE(ImportBlendShapes);
+    SERIALIZE(CalculateBoneOffsetMatrices);
     SERIALIZE(LightmapUVsSource);
     SERIALIZE(CollisionMeshesPrefix);
     SERIALIZE(Scale);
@@ -413,6 +414,7 @@ void ModelTool::Options::Deserialize(DeserializeStream& stream, ISerializeModifi
     DESERIALIZE(ImportLODs);
     DESERIALIZE(ImportVertexColors);
     DESERIALIZE(ImportBlendShapes);
+    DESERIALIZE(CalculateBoneOffsetMatrices);
     DESERIALIZE(LightmapUVsSource);
     DESERIALIZE(CollisionMeshesPrefix);
     DESERIALIZE(Scale);
@@ -1418,6 +1420,15 @@ bool ModelTool::ImportModel(const String& path, ModelData& meshData, Options& op
         SkeletonUpdater<ImportedModelData::Node> hierarchyUpdater(data.Nodes);
         hierarchyUpdater.UpdateMatrices();
 
+        if (options.CalculateBoneOffsetMatrices)
+        {
+            // Calculate offset matrix (inverse bind pose transform) for every bone manually
+            for (SkeletonBone& bone : data.Skeleton.Bones)
+            {
+                CalculateBoneOffsetMatrix(data.Skeleton.Nodes, bone.OffsetMatrix, bone.NodeIndex);
+            }
+        }
+
         // Move meshes in the new nodes
         for (int32 lodIndex = 0; lodIndex < data.LODs.Count(); lodIndex++)
         {
@@ -1439,15 +1450,6 @@ bool ModelTool::ImportModel(const String& path, ModelData& meshData, Options& op
             }
         }
 
-        // TODO: allow to link skeleton asset to model to retarget model bones skeleton for an animation
-        // use SkeletonMapping<SkeletonBone> to map bones?
-
-        // Calculate offset matrix (inverse bind pose transform) for every bone manually
-        /*for (SkeletonBone& bone : data.Skeleton.Bones)
-        {
-            CalculateBoneOffsetMatrix(data.Skeleton.Nodes, bone.OffsetMatrix, bone.NodeIndex);
-        }*/
-
 #if USE_SKELETON_NODES_SORTING
         // Sort skeleton nodes and bones hierarchy (parents first)
         // Then it can be used with a simple linear loop update
diff --git a/Source/Engine/Tools/ModelTool/ModelTool.h b/Source/Engine/Tools/ModelTool/ModelTool.h
index bad10b86e..f5d0b07a7 100644
--- a/Source/Engine/Tools/ModelTool/ModelTool.h
+++ b/Source/Engine/Tools/ModelTool/ModelTool.h
@@ -258,6 +258,9 @@ public:
         // Enable/disable importing blend shapes (morph targets).
         API_FIELD(Attributes="EditorOrder(85), EditorDisplay(\"Geometry\"), VisibleIf(nameof(ShowSkinnedModel))")
         bool ImportBlendShapes = false;
+        // Enable skeleton bones offset matrices recalculating.
+        API_FIELD(Attributes="EditorOrder(86), EditorDisplay(\"Geometry\"), VisibleIf(nameof(ShowSkinnedModel))")
+        bool CalculateBoneOffsetMatrices = false;
         // The lightmap UVs source.
         API_FIELD(Attributes="EditorOrder(90), EditorDisplay(\"Geometry\", \"Lightmap UVs Source\"), VisibleIf(nameof(ShowModel))")
         ModelLightmapUVsSource LightmapUVsSource = ModelLightmapUVsSource::Disable;