Can I use
glTexImage2D() and / or
glTexSubImage2D() (or maybe there's some other method I don't know about) with an already existing block of memory, instead of always uploading the changed pixels? I already have the changed pixels somewhere in memory, and I'd like to send a pointer to that location if possible.
The problem is that I'm likely going to update a large amount of pixels, and uploading all of them introduces a lot of overhead and wasted memory. And since the application will only run on a mobile device without dedicated GPU memory, all I'm doing now is copying a big chunk of memory to another location of the same memory...
Also, I'm looking for a solution that would work on iOS devices, since the application will only run on iOS.