OPENGL RENDERING IN VR HMD

We are trying to implement a Native Rendering Plugin in order to render external OpenGL-source
inside a VR-application for the Oculus Rift. OpenGL code is written in C++.
The rendering the OpenGL-computed triangle only appears on the monitor, not inside the VR-headset.
Is there a way to set the triangle relative to a gameObject inside Unity like the Unity OpenGL emulated command “GL.MultMatrix(MultMatrix.localToWorldMatrix);” produces?
Thank you very much and best regards