问题
I would like to apply some effects on the camera preview. In fact, I want to extend the upper half portion. Actually, I do it with the fragment shader but it's still in the off screen. So how can I translate the off screen in the screen after the process of my shader (translate y=1.5 to y=1.0)? I tried with a matrix but it displays a green square.
explanation
Thank you
edit: Here is a simple example to describe my problem. To simplify, I want to make something in the off screen (during the shader operation) and after I want to translate the off screen in the screen... So I have a preview, then with a shader I "translate" the picture to the bottom to have an half of the picture off screen. To finish, I apply a matrix (not in the shader) to translate it, and so reverse the first translation but it doesn't work ! The half that was in the screen after the first translation is well translated in the top of the screen, but the half that was off screen after the first translation is not translated (we can see only green pixels instead of it).
example 2
Do you know why ?
Thank you
来源：https://stackoverflow.com/questions/37410154/opengl-es-how-display-off-screen