From f59b8b3a5990360d1d7437abec6761eabf67ac8a Mon Sep 17 00:00:00 2001
From: Angelo Scandaliato <angelo@adtile.me>
Date: Thu, 6 Oct 2016 12:56:34 -0700
Subject: [PATCH] export inverseBindMatrix Data for skins

---
 code/glTFAssetWriter.inl |  4 ++++
 code/glTFExporter.cpp    | 26 ++++++++++++++++----------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/code/glTFAssetWriter.inl b/code/glTFAssetWriter.inl
index 3589ceee7..1b119870d 100644
--- a/code/glTFAssetWriter.inl
+++ b/code/glTFAssetWriter.inl
@@ -439,6 +439,10 @@ namespace glTF {
             obj.AddMember("bindShapeMatrix", MakeValue(val, b.bindShapeMatrix.value, w.mAl).Move(), w.mAl);
         }
 
+        if (b.inverseBindMatrices) {
+            obj.AddMember("inverseBindMatrices", Value(b.inverseBindMatrices->id, w.mAl).Move(), w.mAl);
+        }
+
     }
 
     inline void Write(Value& obj, Technique& b, AssetWriter& w)
diff --git a/code/glTFExporter.cpp b/code/glTFExporter.cpp
index d3179e56a..e41747381 100644
--- a/code/glTFExporter.cpp
+++ b/code/glTFExporter.cpp
@@ -144,7 +144,7 @@ glTFExporter::glTFExporter(const char* filename, IOSystem* pIOSystem, const aiSc
 
     ExportAnimations();
 
-    // ExportSkins();
+    ExportSkins();
 
     glTF::AssetWriter writer(*mAsset);
 
@@ -843,41 +843,47 @@ void glTFExporter::ExportAnimations()
 
 void glTFExporter::ExportSkins()
 {
+    Ref<Buffer> bufferRef = mAsset->buffers.Get(unsigned (0));
+
     for (unsigned int idx_mesh = 0; idx_mesh < mScene->mNumMeshes; ++idx_mesh) {
         const aiMesh* aim = mScene->mMeshes[idx_mesh];
 
-        if(!aim->HasBones()) { continue; } // skip to next mesh if no bones.
+        if(!aim->HasBones()) { continue; } // skip to next mesh if no bones exist.
 
         std::string skinName = aim->mName.C_Str();
         skinName = mAsset->FindUniqueID(skinName, "skin");
         Ref<Skin> skinRef = mAsset->skins.Create(skinName);
         skinRef->name = skinName;
 
+        mat4* inverseBindMatricesData = new mat4[aim->mNumBones];
+
         for (unsigned int idx_bone = 0; idx_bone < aim->mNumBones; ++idx_bone) {
             const aiBone* aib = aim->mBones[idx_bone];
 
+            // aib->mName   =====>  skinRef->jointNames
+            // Find the node with id = mName.
             Ref<Node> nodeRef = mAsset->nodes.Get(aib->mName.C_Str());
             nodeRef->jointName = "joint_" + std::to_string(idx_bone);
-
             skinRef->jointNames.push_back("joint_" + std::to_string(idx_bone));
-
             std::cout << "Node->id " << nodeRef->id << "\n";
 
-
+            // Identity Matrix   =====>  skinRef->bindShapeMatrix
+            // Temporary. Hard-coded identity matrix here
             skinRef->bindShapeMatrix.isPresent = true;
-            // CopyValue(n->mTransformation, skinRef->bindShapeMatrix.value);
-            // aiIdentityMatrix4(skinRef->bindShapeMatrix.value);
             IdentityMatrix4(skinRef->bindShapeMatrix.value);
 
-            // skinRef->bindShapeMatrix;
-            // skinRef->inverseBindMatrices;
+
+            // aib->mOffsetMatrix   =====>  skinRef->inverseBindMatrices
+            CopyValue(aib->mOffsetMatrix, inverseBindMatricesData[idx_bone]);
 
             // aib->mNumWeights;
-            // aib->mOffsetMatrix;
             // aib->mWeights;
 
         } // End: for-loop mNumMeshes
 
+        Ref<Accessor> invBindMatrixAccessor = ExportAnimationData(*mAsset, skinName, bufferRef, aim->mNumBones, inverseBindMatricesData, AttribType::MAT4, AttribType::MAT4, ComponentType_FLOAT);
+        if (invBindMatrixAccessor) skinRef->inverseBindMatrices = invBindMatrixAccessor;
+
     } // End: for-loop mNumMeshes
 }