It would be a LOT faster to use glReadPixels, and only read off to main memory the area the size of the actual pixels you want to know about, otherwise you are doing a heck of a lot of unnecessary conversion and transfer.
All you need to do is glReadPixels() the pixel(s) you want to know, read it into some kind of buffer or bank or whatever, then use `Peek` or something to access the values.
All you need to do is glReadPixels() the pixel(s) you want to know, read it into some kind of buffer or bank or whatever, then use `Peek` or something to access the values.