diff --git a/BMap/BMExports.cpp b/BMap/BMExports.cpp
index 73b9c32..596f126 100644
--- a/BMap/BMExports.cpp
+++ b/BMap/BMExports.cpp
@@ -1,16 +1,47 @@
 #include "BMExports.hpp"
 #include <IronPad.hpp>
 #include <set>
+#include <type_traits>
+#include <memory>
+
+#pragma region Help & Save Functions
 
 static bool g_IsInited = false;
 static std::set<BMap::BMFile*> g_AllBMFiles = std::set<BMap::BMFile*>();
 static std::set<BMap::BMMeshTransition*> g_AllBMMeshTrans = std::set<BMap::BMMeshTransition*>();
 
+bool CheckInited() {
+	return g_IsInited;
+}
+
+bool CheckBMFile(BMap::BMFile* possible_bmfile) {
+	return (g_IsInited && possible_bmfile != nullptr && g_AllBMFiles.contains(possible_bmfile));
+}
+
+bool CheckBMMeshTrans(BMap::BMMeshTransition* possible_trans) {
+	return (g_IsInited && possible_trans != nullptr && g_AllBMMeshTrans.contains(possible_trans));
+}
+
+template<class _Ty, std::enable_if_t<std::is_pointer_v<_Ty>, int> = 0>
+_Ty CheckCKObject(BMap::BMFile* possible_bmfile, LibCmo::CK2::CK_ID possible_id, LibCmo::CK2::CK_CLASSID expected_cid) {
+	// check bm file self.
+	if (!CheckBMFile(possible_bmfile)) return nullptr;
+	// check id
+	LibCmo::CK2::ObjImpls::CKObject* obj = possible_bmfile->GetObjectPtr(possible_id);
+	// check id validation and class id
+	if (obj == nullptr || LibCmo::CK2::CKIsChildClassOf(obj->GetClassID(), expected_cid)) return nullptr;
+
+	return static_cast<_Ty>(obj);
+}
+
+#pragma endregion
+
 void BMInit() {
 	// register IronPad
 	IronPad::IronPadRegister();
 	// and startup CK environment
 	LibCmo::CK2::CKStartUp();
+
 	// set init
 	g_IsInited = true;
 }
@@ -29,6 +60,7 @@ void BMDispose() {
 
 	// disable init
 	g_IsInited = false;
+
 	// shutdown CK environment
 	LibCmo::CK2::CKShutdown();
 	// unregister iron pad
@@ -38,141 +70,180 @@ void BMDispose() {
 #pragma region BMFile
 
 BMap::BMFile* BMFile_Load(LibCmo::CKSTRING file_name, LibCmo::CKSTRING temp_folder, LibCmo::CKSTRING texture_folder, LibCmo::CKDWORD encoding_count, LibCmo::CKSTRING encodings[]) {
-	if (!g_IsInited) return nullptr;
-	auto file = new BMap::BMFile(temp_folder, texture_folder, encoding_count, encodings, false);
-	if (file->IsFailed()) {
-		delete file;
-		file = nullptr;
-	}
-	if (!file->Load(file_name)) {
-		delete file;
-		file = nullptr;
-	}
+	if (!CheckInited()) return nullptr;
 
-	g_AllBMFiles.emplace(file);
-	return file;
+	// create a now one and try to load data.
+	std::unique_ptr<BMap::BMFile> file(new BMap::BMFile(temp_folder, texture_folder, encoding_count, encodings, false));
+	if (file->IsFreezed()) return nullptr;
+	if (!file->Load(file_name)) return nullptr;
+
+	// add into list and return
+	g_AllBMFiles.emplace(file.get());
+	return file.release();
 }
 
 BMap::BMFile* BMFile_Create(LibCmo::CKSTRING temp_folder, LibCmo::CKSTRING texture_folder, LibCmo::CKDWORD encoding_count, LibCmo::CKSTRING encodings[]) {
-	if (!g_IsInited) return nullptr;
-	auto file = new BMap::BMFile(temp_folder, texture_folder, encoding_count, encodings, false);
-	if (file->IsFailed()) {
-		delete file;
-		file = nullptr;
-	}
+	if (!CheckInited()) return nullptr;
 
-	g_AllBMFiles.emplace(file);
-	return file;
+	// create a now one
+	std::unique_ptr<BMap::BMFile> file(new BMap::BMFile(temp_folder, texture_folder, encoding_count, encodings, false));
+	if (file->IsFreezed()) return nullptr;
+
+	// add into list and return if success
+	g_AllBMFiles.emplace(file.get());
+	return file.release();
 }
 
 bool BMFile_Save(BMap::BMFile* map_file, LibCmo::CKSTRING file_name, LibCmo::CKINT compreess_level) {
-	if (!g_AllBMFiles.contains(map_file)) return false;
+	if (!CheckBMFile(map_file)) return false;
+
 	return map_file->Save(file_name, compreess_level);
 }
 
-void BMFile_Free(BMap::BMFile* map_file) {
-	// only free correct pointer
-	if (map_file == nullptr) return;
-	if (g_AllBMFiles.erase(map_file) != 0) {
-		delete map_file;
-	}
+bool BMFile_Free(BMap::BMFile* map_file) {
+	if (!CheckBMFile(map_file)) return false;
+
+	g_AllBMFiles.erase(map_file);
+	delete map_file;
+	return true;
 }
 
-#define VISITOR_IMPL(namepart, cidpart) \
-LibCmo::CKDWORD BMFile_Get ## namepart ## Count(BMap::BMFile* map_file) { \
-	if (!g_AllBMFiles.contains(map_file)) return 0; \
-	return map_file->Get ## namepart ## Count(); \
-} \
-LibCmo::CK2::ObjImpls::CK ## namepart * BMFile_Get ## namepart (BMap::BMFile* map_file, LibCmo::CKDWORD idx) { \
-	if (!g_AllBMFiles.contains(map_file)) return nullptr; \
-	return map_file->Get ## namepart (idx); \
-} \
-LibCmo::CK2::ObjImpls::CK ## namepart * BMFile_Create ## namepart (BMap::BMFile* map_file, LibCmo::CKSTRING name) { \
-	if (!g_AllBMFiles.contains(map_file)) return nullptr; \
-	return map_file->Create ## namepart (name); \
+LibCmo::CKDWORD BMFile_GetGroupCount(BMap::BMFile* bmfile) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetGroupCount();
+}
+LibCmo::CK2::CK_ID BMFile_GetGroup(BMap::BMFile* bmfile, LibCmo::CKDWORD idx) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetGroup(idx);
+}
+LibCmo::CK2::CK_ID BMFile_CreateGroup(BMap::BMFile* bmfile, LibCmo::CKSTRING name) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->CreateGroup(name);
+}
+LibCmo::CKDWORD BMFile_Get3dObjectCount(BMap::BMFile* bmfile) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->Get3dObjectCount();
+}
+LibCmo::CK2::CK_ID BMFile_Get3dObject(BMap::BMFile* bmfile, LibCmo::CKDWORD idx) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->Get3dObject(idx);
+}
+LibCmo::CK2::CK_ID BMFile_Create3dObject(BMap::BMFile* bmfile, LibCmo::CKSTRING name) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->Create3dObject(name);
+}
+LibCmo::CKDWORD BMFile_GetMeshCount(BMap::BMFile* bmfile) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetMeshCount();
+}
+LibCmo::CK2::CK_ID BMFile_GetMesh(BMap::BMFile* bmfile, LibCmo::CKDWORD idx) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetMesh(idx);
+}
+LibCmo::CK2::CK_ID BMFile_CreateMesh(BMap::BMFile* bmfile, LibCmo::CKSTRING name) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->CreateMesh(name);
+}
+LibCmo::CKDWORD BMFile_GetMaterialCount(BMap::BMFile* bmfile) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetMaterialCount();
+}
+LibCmo::CK2::CK_ID BMFile_GetMaterial(BMap::BMFile* bmfile, LibCmo::CKDWORD idx) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetMaterial(idx);
+}
+LibCmo::CK2::CK_ID BMFile_CreateMaterial(BMap::BMFile* bmfile, LibCmo::CKSTRING name) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->CreateMaterial(name);
+}
+LibCmo::CKDWORD BMFile_GetTextureCount(BMap::BMFile* bmfile) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetTextureCount();
+}
+LibCmo::CK2::CK_ID BMFile_GetTexture(BMap::BMFile* bmfile, LibCmo::CKDWORD idx) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->GetTexture(idx);
+}
+LibCmo::CK2::CK_ID BMFile_CreateTexture(BMap::BMFile* bmfile, LibCmo::CKSTRING name) {
+	if (!CheckBMFile(bmfile)) return 0;
+	return bmfile->CreateTexture(name);
 }
-
-VISITOR_IMPL(Group, GROUP)
-VISITOR_IMPL(3dObject, 3DOBJECT)
-VISITOR_IMPL(Mesh, MESH)
-VISITOR_IMPL(Material, MATERIAL)
-VISITOR_IMPL(Texture, TEXTURE)
-
-#undef VISITOR_IMPL
 
 #pragma endregion
 
 #pragma region BMMeshTransition
 
 BMap::BMMeshTransition* BMMeshTrans_New() {
-	if (!g_IsInited) return nullptr;
+	if (!CheckInited()) return nullptr;
+
+	// create new one, insert and return.
 	auto meshtrans = new BMap::BMMeshTransition();
 	g_AllBMMeshTrans.emplace(meshtrans);
 	return meshtrans;
 }
 
-void BMMeshTrans_Delete(BMap::BMMeshTransition* trans) {
-	// only free correct pointer
-	if (trans == nullptr) return;
-	if (g_AllBMMeshTrans.erase(trans) != 0) {
-		delete trans;
-	}
+bool BMMeshTrans_Delete(BMap::BMMeshTransition* trans) {
+	if (!CheckBMMeshTrans(trans)) return false;
+
+	g_AllBMMeshTrans.erase(trans);
+	delete trans;
+	return true;
 }
 
-void BMMeshTrans_PrepareVertexCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
-	if (!g_AllBMMeshTrans.contains(trans)) return;
-	trans->PrepareVertexCount(count);
+bool BMMeshTrans_PrepareVertexCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
+	if (!CheckBMMeshTrans(trans)) return false;
+	return trans->PrepareVertexCount(count);
 }
 LibCmo::VxMath::VxVector3* BMMeshTrans_PrepareVertex(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareVertex();
 }
-void BMMeshTrans_PrepareNormalCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
-	if (!g_AllBMMeshTrans.contains(trans)) return;
-	trans->PrepareNormalCount(count);
+bool BMMeshTrans_PrepareNormalCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
+	if (!CheckBMMeshTrans(trans)) return false;
+	return trans->PrepareNormalCount(count);
 }
 LibCmo::VxMath::VxVector3* BMMeshTrans_PrepareNormal(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareNormal();
 }
-void BMMeshTrans_PrepareUVCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
-	if (!g_AllBMMeshTrans.contains(trans)) return;
-	trans->PrepareUVCount(count);
+bool BMMeshTrans_PrepareUVCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
+	if (!CheckBMMeshTrans(trans)) return false;
+	return trans->PrepareUVCount(count);
 }
 LibCmo::VxMath::VxVector2* BMMeshTrans_PrepareUV(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareUV();
 }
-void BMMeshTrans_PrepareMtlSlotCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
-	if (!g_AllBMMeshTrans.contains(trans)) return;
-	trans->PrepareMtlSlotCount(count);
+bool BMMeshTrans_PrepareMtlSlotCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
+	if (!CheckBMMeshTrans(trans)) return false;
+	return trans->PrepareMtlSlotCount(count);
 }
 LibCmo::CK2::ObjImpls::CKMaterial** BMMeshTrans_PrepareMtlSlot(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareMtlSlot();
 }
-void BMMeshTrans_PrepareFaceCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
-	if (!g_AllBMMeshTrans.contains(trans)) return;
-	trans->PrepareFaceCount(count);
+bool BMMeshTrans_PrepareFaceCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count) {
+	if (!CheckBMMeshTrans(trans)) return false;
+	return trans->PrepareFaceCount(count);
 }
 LibCmo::CKDWORD* BMMeshTrans_PrepareFaceVertexIndices(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareFaceVertexIndices();
 }
 LibCmo::CKDWORD* BMMeshTrans_PrepareFaceNormalIndices(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareFaceNormalIndices();
 }
 LibCmo::CKDWORD* BMMeshTrans_PrepareFaceUVIndices(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareFaceUVIndices();
 }
 LibCmo::CKDWORD* BMMeshTrans_PrepareFaceMtlSlot(BMap::BMMeshTransition* trans) {
-	if (!g_AllBMMeshTrans.contains(trans)) return nullptr;
+	if (!CheckBMMeshTrans(trans)) return nullptr;
 	return trans->PrepareFaceMtlSlot();
 }
 bool BMMeshTrans_Parse(BMap::BMMeshTransition* trans, LibCmo::CK2::ObjImpls::CKMesh* write_into_mesh) {
-	if (!g_AllBMMeshTrans.contains(trans)) return false;
+	if (!CheckBMMeshTrans(trans)) return false;
 	return trans->Parse(write_into_mesh);
 }
 
diff --git a/BMap/BMExports.hpp b/BMap/BMExports.hpp
index 1accfbd..0dbf0f3 100644
--- a/BMap/BMExports.hpp
+++ b/BMap/BMExports.hpp
@@ -14,43 +14,45 @@ LIBCMO_EXPORT void BMDispose();
 LIBCMO_EXPORT BMap::BMFile* BMFile_Load(LibCmo::CKSTRING file_name, LibCmo::CKSTRING temp_folder, LibCmo::CKSTRING texture_folder, LibCmo::CKDWORD encoding_count, LibCmo::CKSTRING encodings[]);
 LIBCMO_EXPORT BMap::BMFile* BMFile_Create(LibCmo::CKSTRING temp_folder, LibCmo::CKSTRING texture_folder, LibCmo::CKDWORD encoding_count, LibCmo::CKSTRING encodings[]);
 LIBCMO_EXPORT bool BMFile_Save(BMap::BMFile* map_file, LibCmo::CKSTRING file_name, LibCmo::CKINT compreess_level);
-LIBCMO_EXPORT void BMFile_Free(BMap::BMFile* map_file);
+LIBCMO_EXPORT bool BMFile_Free(BMap::BMFile* map_file);
 
-#define VISITOR_DECL(namepart) \
-LIBCMO_EXPORT LibCmo::CKDWORD BMFile_Get ## namepart ## Count(BMap::BMFile* map_file); \
-LIBCMO_EXPORT LibCmo::CK2::ObjImpls::CK ## namepart * BMFile_Get ## namepart (BMap::BMFile* map_file, LibCmo::CKDWORD idx); \
-LIBCMO_EXPORT LibCmo::CK2::ObjImpls::CK ## namepart * BMFile_Create ## namepart (BMap::BMFile* map_file, LibCmo::CKSTRING name);
-
-VISITOR_DECL(Group)
-VISITOR_DECL(3dObject)
-VISITOR_DECL(Mesh)
-VISITOR_DECL(Material)
-VISITOR_DECL(Texture)
-
-#undef VISITOR_DECL
+LIBCMO_EXPORT LibCmo::CKDWORD BMFile_GetGroupCount(BMap::BMFile* bmfile);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_GetGroup(BMap::BMFile* bmfile, LibCmo::CKDWORD idx);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_CreateGroup(BMap::BMFile* bmfile, LibCmo::CKSTRING name);
+LIBCMO_EXPORT LibCmo::CKDWORD BMFile_Get3dObjectCount(BMap::BMFile* bmfile);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_Get3dObject(BMap::BMFile* bmfile, LibCmo::CKDWORD idx);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_Create3dObject(BMap::BMFile* bmfile, LibCmo::CKSTRING name);
+LIBCMO_EXPORT LibCmo::CKDWORD BMFile_GetMeshCount(BMap::BMFile* bmfile);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_GetMesh(BMap::BMFile* bmfile, LibCmo::CKDWORD idx);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_CreateMesh(BMap::BMFile* bmfile, LibCmo::CKSTRING name);
+LIBCMO_EXPORT LibCmo::CKDWORD BMFile_GetMaterialCount(BMap::BMFile* bmfile);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_GetMaterial(BMap::BMFile* bmfile, LibCmo::CKDWORD idx);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_CreateMaterial(BMap::BMFile* bmfile, LibCmo::CKSTRING name);
+LIBCMO_EXPORT LibCmo::CKDWORD BMFile_GetTextureCount(BMap::BMFile* bmfile);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_GetTexture(BMap::BMFile* bmfile, LibCmo::CKDWORD idx);
+LIBCMO_EXPORT LibCmo::CK2::CK_ID BMFile_CreateTexture(BMap::BMFile* bmfile, LibCmo::CKSTRING name);
 
 #pragma endregion
 
 #pragma region BMMeshTransition
 
 LIBCMO_EXPORT BMap::BMMeshTransition* BMMeshTrans_New();
-LIBCMO_EXPORT void BMMeshTrans_Delete(BMap::BMMeshTransition* trans);
+LIBCMO_EXPORT bool BMMeshTrans_Delete(BMap::BMMeshTransition* trans);
 
-LIBCMO_EXPORT void BMMeshTrans_PrepareVertexCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
+LIBCMO_EXPORT bool BMMeshTrans_PrepareVertexCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
 LIBCMO_EXPORT LibCmo::VxMath::VxVector3* BMMeshTrans_PrepareVertex(BMap::BMMeshTransition* trans);
-LIBCMO_EXPORT void BMMeshTrans_PrepareNormalCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
+LIBCMO_EXPORT bool BMMeshTrans_PrepareNormalCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
 LIBCMO_EXPORT LibCmo::VxMath::VxVector3* BMMeshTrans_PrepareNormal(BMap::BMMeshTransition* trans);
-LIBCMO_EXPORT void BMMeshTrans_PrepareUVCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
+LIBCMO_EXPORT bool BMMeshTrans_PrepareUVCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
 LIBCMO_EXPORT LibCmo::VxMath::VxVector2* BMMeshTrans_PrepareUV(BMap::BMMeshTransition* trans);
-LIBCMO_EXPORT void BMMeshTrans_PrepareMtlSlotCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
+LIBCMO_EXPORT bool BMMeshTrans_PrepareMtlSlotCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
 LIBCMO_EXPORT LibCmo::CK2::ObjImpls::CKMaterial** BMMeshTrans_PrepareMtlSlot(BMap::BMMeshTransition* trans);
-LIBCMO_EXPORT void BMMeshTrans_PrepareFaceCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
+LIBCMO_EXPORT bool BMMeshTrans_PrepareFaceCount(BMap::BMMeshTransition* trans, LibCmo::CKDWORD count);
 LIBCMO_EXPORT LibCmo::CKDWORD* BMMeshTrans_PrepareFaceVertexIndices(BMap::BMMeshTransition* trans);
 LIBCMO_EXPORT LibCmo::CKDWORD* BMMeshTrans_PrepareFaceNormalIndices(BMap::BMMeshTransition* trans);
 LIBCMO_EXPORT LibCmo::CKDWORD* BMMeshTrans_PrepareFaceUVIndices(BMap::BMMeshTransition* trans);
 LIBCMO_EXPORT LibCmo::CKDWORD* BMMeshTrans_PrepareFaceMtlSlot(BMap::BMMeshTransition* trans);
 LIBCMO_EXPORT bool BMMeshTrans_Parse(BMap::BMMeshTransition* trans, LibCmo::CK2::ObjImpls::CKMesh* write_into_mesh);
-
 #pragma endregion
 
 
diff --git a/BMap/BMap.cpp b/BMap/BMap.cpp
index 821bc6a..267755a 100644
--- a/BMap/BMap.cpp
+++ b/BMap/BMap.cpp
@@ -28,11 +28,12 @@ namespace BMap {
 		m_ProcVertexs(), m_ProcFaces(), m_ProcDupRemover() {}
 
 	BMMeshTransition::~BMMeshTransition() {}
-
-	void BMMeshTransition::PrepareVertexCount(LibCmo::CKDWORD count) {
-		if (m_IsParsed) return;
+	
+	bool BMMeshTransition::PrepareVertexCount(LibCmo::CKDWORD count) {
+		if (m_IsParsed) return false;
 		m_Vertexs.resize(count);
 		m_IsVertexOK = true;
+		return true;
 	}
 
 	LibCmo::VxMath::VxVector3* BMMeshTransition::PrepareVertex() {
@@ -40,10 +41,11 @@ namespace BMap {
 		return m_Vertexs.data();
 	}
 
-	void BMMeshTransition::PrepareNormalCount(LibCmo::CKDWORD count) {
-		if (m_IsParsed) return;
+	bool BMMeshTransition::PrepareNormalCount(LibCmo::CKDWORD count) {
+		if (m_IsParsed) return false;
 		m_Normals.resize(count);
 		m_IsNormalOK = true;
+		return true;
 	}
 
 	LibCmo::VxMath::VxVector3* BMMeshTransition::PrepareNormal() {
@@ -51,10 +53,11 @@ namespace BMap {
 		return m_Normals.data();
 	}
 
-	void BMMeshTransition::PrepareUVCount(LibCmo::CKDWORD count) {
-		if (m_IsParsed) return;
+	bool BMMeshTransition::PrepareUVCount(LibCmo::CKDWORD count) {
+		if (m_IsParsed) return false;
 		m_UVs.resize(count);
 		m_IsUVOK = true;
+		return true;
 	}
 
 	LibCmo::VxMath::VxVector2* BMMeshTransition::PrepareUV() {
@@ -62,10 +65,11 @@ namespace BMap {
 		return m_UVs.data();
 	}
 
-	void BMMeshTransition::PrepareMtlSlotCount(LibCmo::CKDWORD count) {
-		if (m_IsParsed) return;
+	bool BMMeshTransition::PrepareMtlSlotCount(LibCmo::CKDWORD count) {
+		if (m_IsParsed) return false;
 		m_MtlSlots.resize(count, nullptr);
 		m_IsMtlSlotOK = true;
+		return true;
 	}
 
 	LibCmo::CK2::ObjImpls::CKMaterial** BMMeshTransition::PrepareMtlSlot() {
@@ -73,13 +77,14 @@ namespace BMap {
 		return m_MtlSlots.data();
 	}
 
-	void BMMeshTransition::PrepareFaceCount(LibCmo::CKDWORD count) {
-		if (m_IsParsed) return;
+	bool BMMeshTransition::PrepareFaceCount(LibCmo::CKDWORD count) {
+		if (m_IsParsed) return false;
 		m_FaceVertexs.resize(count * 3);
 		m_FaceNormals.resize(count * 3);
 		m_FaceUVs.resize(count * 3);
 		m_FaceMtlSlotIdxs.resize(count);
 		m_IsFaceOK = true;
+		return true;
 	}
 
 	LibCmo::CKDWORD* BMMeshTransition::PrepareFaceVertexIndices() {
@@ -217,12 +222,12 @@ namespace BMap {
 #pragma region BMfile
 
 	BMFile::BMFile(LibCmo::CKSTRING temp_folder, LibCmo::CKSTRING texture_folder, LibCmo::CKDWORD encoding_count, LibCmo::CKSTRING encodings[], bool is_reader) :
-		m_IsReader(is_reader), m_IsFailed(false) {
+		m_IsReader(is_reader), m_IsFreezed(false) {
 		m_Context = new LibCmo::CK2::CKContext();
 		// set temp folder and texture folder
 		auto pm = m_Context->GetPathManager();
-		m_IsFailed = m_IsFailed || !pm->AddPath(texture_folder);
-		m_IsFailed = m_IsFailed || !pm->SetTempFolder(temp_folder);
+		m_IsFreezed = m_IsFreezed || !pm->AddPath(texture_folder);
+		m_IsFreezed = m_IsFreezed || !pm->SetTempFolder(temp_folder);
 		// set encoding
 		LibCmo::XContainer::XArray<LibCmo::XContainer::XString> cache;
 		for (LibCmo::CKDWORD i = 0; i < encoding_count; ++i) {
@@ -238,43 +243,54 @@ namespace BMap {
 		delete m_Context;
 	}
 
-	bool BMFile::IsFailed() {
-		return m_IsFailed;
+	bool BMFile::IsFreezed() {
+		return m_IsFreezed;
 	}
 
 	bool BMFile::Load(LibCmo::CKSTRING filename) {
-		return false;
+		if (m_IsFreezed || !m_IsReader) return false;
+		
+		return true;
 	}
 
 	bool BMFile::Save(LibCmo::CKSTRING filename, LibCmo::CKINT compress_level) {
-		return false;
+		if (m_IsFreezed || m_IsReader) return false;
+
+		// set freezed to stop any change again.
+		// aka, only allow save once.
+		m_IsFreezed = true;
+		return true;
 	}
 
-#define VISITOR_IMPL(namepart, cidpart) \
-LibCmo::CKDWORD BMFile::Get ## namepart ## Count() { \
-	if (!m_IsReader) return 0; \
-	return static_cast<LibCmo::CKDWORD>(m_Obj ## namepart ## s.size()); \
-} \
-LibCmo::CK2::ObjImpls::CK ## namepart * BMFile::Get ## namepart (LibCmo::CKDWORD idx) { \
-	if (!m_IsReader || idx >= m_Obj ## namepart ## s.size()) return nullptr; \
-	return m_Obj ## namepart ## s[idx]; \
-} \
-LibCmo::CK2::ObjImpls::CK ## namepart * BMFile::Create ## namepart (LibCmo::CKSTRING name) { \
-	if (m_IsReader) return nullptr; \
-	LibCmo::CK2::ObjImpls::CK ## namepart * obj = static_cast<LibCmo::CK2::ObjImpls::CK ## namepart *>( \
-		m_Context->CreateObject(LibCmo::CK2::CK_CLASSID::CKCID_ ## cidpart, name) \
-		); \
-	if (obj != nullptr) m_Obj ## namepart ## s.emplace_back(obj); \
-	return obj; \
-}
+	LibCmo::CK2::ObjImpls::CKObject* BMFile::GetObjectPtr(LibCmo::CK2::CK_ID objid) {
+		return m_Context->GetObject(objid);;
+	}
 
-	VISITOR_IMPL(Group, GROUP)
-		VISITOR_IMPL(3dObject, 3DOBJECT)
-		VISITOR_IMPL(Mesh, MESH)
-		VISITOR_IMPL(Material, MATERIAL)
-		VISITOR_IMPL(Texture, TEXTURE)
-
-#undef VISITOR_IMPL
+	LibCmo::CKDWORD BMFile::GetGroupCount() { return CommonGetObjectCount(m_ObjGroups); }
+	LibCmo::CK2::CK_ID BMFile::GetGroup(LibCmo::CKDWORD idx) { return CommonGetObject(m_ObjGroups, idx); }
+	LibCmo::CK2::CK_ID BMFile::CreateGroup(LibCmo::CKSTRING name) {
+		return CommonCreateObject(m_ObjGroups, LibCmo::CK2::CK_CLASSID::CKCID_GROUP, name);
+	}
+	LibCmo::CKDWORD BMFile::Get3dObjectCount() { return CommonGetObjectCount(m_Obj3dObjects); }
+	LibCmo::CK2::CK_ID BMFile::Get3dObject(LibCmo::CKDWORD idx) { return CommonGetObject(m_Obj3dObjects, idx); }
+	LibCmo::CK2::CK_ID BMFile::Create3dObject(LibCmo::CKSTRING name) {
+		return CommonCreateObject(m_Obj3dObjects, LibCmo::CK2::CK_CLASSID::CKCID_3DOBJECT, name);
+	}
+	LibCmo::CKDWORD BMFile::GetMeshCount() { return CommonGetObjectCount(m_ObjMeshs); }
+	LibCmo::CK2::CK_ID BMFile::GetMesh(LibCmo::CKDWORD idx) { return CommonGetObject(m_ObjMeshs, idx); }
+	LibCmo::CK2::CK_ID BMFile::CreateMesh(LibCmo::CKSTRING name) {
+		return CommonCreateObject(m_ObjMeshs, LibCmo::CK2::CK_CLASSID::CKCID_MESH, name);
+	}
+	LibCmo::CKDWORD BMFile::GetMaterialCount() { return CommonGetObjectCount(m_ObjMaterials); }
+	LibCmo::CK2::CK_ID BMFile::GetMaterial(LibCmo::CKDWORD idx) { return CommonGetObject(m_ObjMaterials, idx); }
+	LibCmo::CK2::CK_ID BMFile::CreateMaterial(LibCmo::CKSTRING name) {
+		return CommonCreateObject(m_ObjMaterials, LibCmo::CK2::CK_CLASSID::CKCID_MATERIAL, name);
+	}
+	LibCmo::CKDWORD BMFile::GetTextureCount() { return CommonGetObjectCount(m_ObjTextures); }
+	LibCmo::CK2::CK_ID BMFile::GetTexture(LibCmo::CKDWORD idx) { return CommonGetObject(m_ObjTextures, idx); }
+	LibCmo::CK2::CK_ID BMFile::CreateTexture(LibCmo::CKSTRING name) {
+		return CommonCreateObject(m_ObjTextures, LibCmo::CK2::CK_CLASSID::CKCID_TEXTURE, name);
+	}
 
 #pragma endregion
 
diff --git a/BMap/BMap.hpp b/BMap/BMap.hpp
index 00fb988..b99a0f2 100644
--- a/BMap/BMap.hpp
+++ b/BMap/BMap.hpp
@@ -4,6 +4,7 @@
 #include <vector>
 #include <cstdint>
 #include <cinttypes>
+#include <type_traits>
 
 namespace BMap {
 	
@@ -32,15 +33,15 @@ namespace BMap {
 		~BMMeshTransition();
 		LIBCMO_DISABLE_COPY_MOVE(BMMeshTransition);
 
-		void PrepareVertexCount(LibCmo::CKDWORD count);
+		bool PrepareVertexCount(LibCmo::CKDWORD count);
 		LibCmo::VxMath::VxVector3* PrepareVertex();
-		void PrepareNormalCount(LibCmo::CKDWORD count);
+		bool PrepareNormalCount(LibCmo::CKDWORD count);
 		LibCmo::VxMath::VxVector3* PrepareNormal();
-		void PrepareUVCount(LibCmo::CKDWORD count);
+		bool PrepareUVCount(LibCmo::CKDWORD count);
 		LibCmo::VxMath::VxVector2* PrepareUV();
-		void PrepareMtlSlotCount(LibCmo::CKDWORD count);
+		bool PrepareMtlSlotCount(LibCmo::CKDWORD count);
 		LibCmo::CK2::ObjImpls::CKMaterial** PrepareMtlSlot();
-		void PrepareFaceCount(LibCmo::CKDWORD count);
+		bool PrepareFaceCount(LibCmo::CKDWORD count);
 		LibCmo::CKDWORD* PrepareFaceVertexIndices();
 		LibCmo::CKDWORD* PrepareFaceNormalIndices();
 		LibCmo::CKDWORD* PrepareFaceUVIndices();
@@ -78,38 +79,73 @@ namespace BMap {
 		~BMFile();
 		LIBCMO_DISABLE_COPY_MOVE(BMFile);
 
-		bool IsFailed();
+		// ===== help functions ===== 
+
+		/**
+		 * @brief Check whether this instance is freezed.
+		 * @return True if freezed. This instance should be free immediately.
+		*/
+		bool IsFreezed();
 		bool Load(LibCmo::CKSTRING filename);
 		bool Save(LibCmo::CKSTRING filename, LibCmo::CKINT compress_level);
+		LibCmo::CK2::ObjImpls::CKObject* GetObjectPtr(LibCmo::CK2::CK_ID objid);
 
-#define VISITOR_DECL(namepart) \
-LibCmo::CKDWORD Get ## namepart ## Count(); \
-LibCmo::CK2::ObjImpls::CK ## namepart * Get ## namepart (LibCmo::CKDWORD idx); \
-LibCmo::CK2::ObjImpls::CK ## namepart * Create ## namepart (LibCmo::CKSTRING name);
-
-		VISITOR_DECL(Group)
-		VISITOR_DECL(3dObject)
-		VISITOR_DECL(Mesh)
-		VISITOR_DECL(Material)
-		VISITOR_DECL(Texture)
-
-#undef VISITOR_DECL
+		// ===== visitors ===== 
 
 	private:
-		bool m_IsFailed;
+		LibCmo::CKDWORD CommonGetObjectCount(std::vector<LibCmo::CK2::CK_ID>& container) {
+			if (m_IsFreezed || !m_IsReader) return 0;
+			return static_cast<LibCmo::CKDWORD>(container.size());
+		}
+		LibCmo::CK2::CK_ID CommonGetObject(std::vector<LibCmo::CK2::CK_ID>& container, LibCmo::CKDWORD idx) {
+			if (m_IsFreezed || !m_IsReader || idx >= container.size()) return 0;
+			return container[idx];
+		}
+		LibCmo::CK2::CK_ID CommonCreateObject(std::vector<LibCmo::CK2::CK_ID>& container, LibCmo::CK2::CK_CLASSID cid, LibCmo::CKSTRING name) {
+			// only available in writer
+			if (m_IsFreezed || m_IsReader) return 0;
+
+			// try create object and get its pointer
+			LibCmo::CK2::ObjImpls::CKObject* obj = m_Context->CreateObject(cid, name);
+			// check creation validation
+			if (obj == nullptr) return 0;
+
+			// if success, write its id and emplace its id into list
+			LibCmo::CK2::CK_ID objid = obj->GetID();
+			container.emplace_back(objid);
+			return objid;
+		}
+	public:
+		LibCmo::CKDWORD GetGroupCount();
+		LibCmo::CK2::CK_ID GetGroup(LibCmo::CKDWORD idx);
+		LibCmo::CK2::CK_ID CreateGroup(LibCmo::CKSTRING name);
+		LibCmo::CKDWORD Get3dObjectCount();
+		LibCmo::CK2::CK_ID Get3dObject(LibCmo::CKDWORD idx);
+		LibCmo::CK2::CK_ID Create3dObject(LibCmo::CKSTRING name);
+		LibCmo::CKDWORD GetMeshCount();
+		LibCmo::CK2::CK_ID GetMesh(LibCmo::CKDWORD idx);
+		LibCmo::CK2::CK_ID CreateMesh(LibCmo::CKSTRING name);
+		LibCmo::CKDWORD GetMaterialCount();
+		LibCmo::CK2::CK_ID GetMaterial(LibCmo::CKDWORD idx);
+		LibCmo::CK2::CK_ID CreateMaterial(LibCmo::CKSTRING name);
+		LibCmo::CKDWORD GetTextureCount();
+		LibCmo::CK2::CK_ID GetTexture(LibCmo::CKDWORD idx);
+		LibCmo::CK2::CK_ID CreateTexture(LibCmo::CKSTRING name);
+
+	private:
+		/**
+		 * @brief True if all operation of this instance should be rejected.
+		*/
+		bool m_IsFreezed;
 		bool m_IsReader;
 		LibCmo::CK2::CKContext* m_Context;
 
-#define VISITOR_SELF(namepart) \
-std::vector<LibCmo::CK2::ObjImpls::CK ## namepart *> m_Obj ## namepart ## s;
+		std::vector<LibCmo::CK2::CK_ID> m_ObjGroups;
+		std::vector<LibCmo::CK2::CK_ID> m_Obj3dObjects;
+		std::vector<LibCmo::CK2::CK_ID> m_ObjMeshs;
+		std::vector<LibCmo::CK2::CK_ID> m_ObjMaterials;
+		std::vector<LibCmo::CK2::CK_ID> m_ObjTextures;
 
-		VISITOR_SELF(Group)
-		VISITOR_SELF(3dObject)
-		VISITOR_SELF(Mesh)
-		VISITOR_SELF(Material)
-		VISITOR_SELF(Texture)
-
-#undef VISITOR_SELF
 	};
 
 }