refacored some parts of main.cpp

start.sh

@@ -1,7 +1,7 @@
 g++ Game.cpp main.cpp Math.cpp OpenGlExtensions.cpp Physics.cpp Renderer.cpp \
     ShaderManager.cpp TextureManager.cpp Utils.cpp BoneAnimatedModel.cpp \
     ObjLoader.cpp cmakeaudioplayer/src/AudioPlayer.cpp TextModel.cpp \
-    Inventory.cpp Environment.cpp GameObjectManager.cpp \
+    Inventory.cpp Environment.cpp GameObjectManager.cpp RenderSystem.cpp \
     -o sdl_app -O2 -std=c++17 \
     -I cmakeaudioplayer/include \
     $(pkg-config --cflags --libs sdl2 gl) \