diff --git a/FinalProject/model.cpp b/FinalProject/model.cpp
index 6a313d9..3f3ee94 100644
--- a/FinalProject/model.cpp
+++ b/FinalProject/model.cpp
@@ -34,6 +34,8 @@ void Model::loadModel(std::string path) {
     processNode(scene->mRootNode, scene);
     _status = LOADED;
     Logger::info("Model loaded");
+    // 仅检查一次即可
+    check_boundary();
 }
 
 void Model::processNode(aiNode* node, const aiScene* scene) {
diff --git a/FinalProject/model.h b/FinalProject/model.h
index 44949ce..7f3df3a 100644
--- a/FinalProject/model.h
+++ b/FinalProject/model.h
@@ -48,10 +48,13 @@ private:
     void processNode(aiNode* node, const aiScene* scene);
     Mesh processMesh(aiMesh* mesh, const aiScene* scene);
     std::vector<Texture> loadMaterialTextures(aiMaterial* mat, aiTextureType type, TextureType textureType);
+    // Since these are loacl position, this function should be called just once.
+    void check_boundary();
 
 public:
     void render(const ShaderProgram& shader) const;
-    void check_boundary();
+
+    
 
     // maybe we can encapsure a function to get both upper and lower bound?
 
diff --git a/FinalProject/renderable.cpp b/FinalProject/renderable.cpp
index 86463a1..a022be4 100644
--- a/FinalProject/renderable.cpp
+++ b/FinalProject/renderable.cpp
@@ -2,9 +2,17 @@
 
 #include "renderable.h"
 
-Renderable::Renderable(Model* model) : _model(model) {}
+// 极值点一定在model包围盒的顶点出取到
 
-Renderable::Renderable(Model* model, glm::vec3 position) : _model(model), _position(position) {}
+Renderable::Renderable(Model* model) : _model(model) {
+    _upper_bound = model->get_upper_bound();
+    _lower_bound = model->get_lower_bound();
+}
+
+Renderable::Renderable(Model* model, glm::vec3 position) : _model(model), _position(position) {
+    _upper_bound = model->get_upper_bound();
+    _lower_bound = model->get_lower_bound();
+}
 
 void Renderable::move(glm::vec3 deltaVec) {
     _position += deltaVec;
@@ -36,3 +44,8 @@ void Renderable::render(ShaderProgram shader) {
     // Render
     _model->render(shader);
 }
+
+// check here to get global boundary
+void Renderable::check_boundary() {
+
+}
\ No newline at end of file
diff --git a/FinalProject/renderable.h b/FinalProject/renderable.h
index 7e5912a..dc13c63 100644
--- a/FinalProject/renderable.h
+++ b/FinalProject/renderable.h
@@ -12,6 +12,9 @@ private:
     glm::vec3 _position = glm::vec3(0.0f);
     glm::mat4 _rotation = glm::mat4(1.0f);
     glm::vec3 _scale = glm::vec3(1.0f);
+    // 下面是与坐标轴平行的顶点
+    glm::vec3 _lower_bound;
+    glm::vec3 _upper_bound;
 
 public:
     Renderable(Model* model);
@@ -29,6 +32,8 @@ public:
 
 public:
     void render(ShaderProgram shader);
+    // check here to get global boundary
+    void check_boundary();
 };
 
 inline glm::mat4 Renderable::modelMatrix() const {