I'm worried an ambiguous spec. about glReadPixels, glCopyTexImage2D and, glCopyTexSubImage2D.
for example, I may use eglMakeCurrent as following and both drawSurface & readSurface are double-buffering.
eglMakeCurrent(defualtDisplay, drawSurface, readSurface, glesContext);
If I use glReadPixels, does it read from the front buffer of readSurface?
In a GL sense, it's correct, but I think the glReadPixels of GLES reads from the current drawing surface(back buffer).
What is correct?
If the above readSurface is same as the drawSurface, how does it work?