diff --git a/src/SceneGraph/Camera.cpp b/src/SceneGraph/Camera.cpp
index 14c4357a..0712a798 100644
--- a/src/SceneGraph/Camera.cpp
+++ b/src/SceneGraph/Camera.cpp
@@ -34,6 +34,9 @@ namespace hgl
 
             matrix.mvp=matrix.projection*matrix.modelview;
 
+            //注意： C++中要 projection * model_view * local_to_world * position
+            //而GLSL中要 position * local_to_world * model_view * projection
+
             matrix.two_dim=ortho(width,height,znear,zfar);
 
             frustum.SetVerticalFovAndAspectRatio(DegToRad(fov),width/height);