There's another case above too:

```c++
// Special case: if we don't need to deal with packing, we don't need to copy.
```

It should be safe to use `Memory::GetPointer()` directly if `gl_extensions.EXT_unpack_subimage` there as well.  That would avoid a bit more copying.  Actually, I suppose it's also safe for `w >= bufw`, not just `w == bufw`.

-[Unknown]