Use OpenGL Texture as Input

Hi, I am writing an Android app (in native C) where I load a MJPEG stream onto a OpenGL Texture (this is already working). I would like to use OpenCV to detect markers on the frames. Is there a way to get a Mat out of an OpenGL Texture directly? The only ways I found to do this are: 1) export the raw data from the OpenGL Texture and create a Mat from there 2) create an OpenCL Image with clCreateFromGLTexture and use it as input for a UMat (how would I do that?) Are there any other ways where the surface stays in OpenGL maybe? Would the second approach work and would it bring better performance?