diff --git a/cg/opengl.md b/cg/opengl.md
index c7cc181..fbf603b 100644
--- a/cg/opengl.md
+++ b/cg/opengl.md
@@ -283,4 +283,7 @@ glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
 - [OpenGL基础，一个韩国人写的基础知识](http://www.songho.ca/opengl/index.html)
 - [OpenGL教程和资料集合](https://zhuanlan.zhihu.com/p/41818595)
 - [OpenGL Loading Library](https://www.khronos.org/opengl/wiki/OpenGL_Loading_Library)
-- [GLRF - OpenGL Realtime Framework](https://github.com/DunkleMango/GLRF)
\ No newline at end of file
+- [GLRF - OpenGL Realtime Framework](https://github.com/DunkleMango/GLRF)
+
+### gizmo
+- [izmo control library for 3D object manipulation (4x4 matrix) ](https://github.com/CedricGuillemet/LibGizmo)
\ No newline at end of file