Confusion on GL methods with Buffer arguments

OpenGL Development JOGL Development
#1

The answer to this question may be in some documentation somewhere (in which case, sorry for wasting forum time), but I can’t seem to find it, and I’m not sure what’s going on…

I’m trying to work with some of the GL interface methods like glDrawPixels and glReadPixels that take New I/O Buffers as the data-storing arguments. But I’m confused by the fact that all of these methods are overloaded with a second method that is identical, but takes “long pixels_buffer_offset” or something similar as an argument. What does this second function do? The docs make it look like its a direct copy of the C function that takes a pointer to a buffer, but that can’t be it, since there are no pointers in Java… but then what could be being “offset” if there’s no data or buffer included in that function?

Thanks.

#2

These are variants intended for use with the vertex_buffer_object or pixel_buffer_object extension and can only be called if those extensions are active (there are run-time checks in the generated code to verify this).

#3

Ah, ok - so there are no versions that support reading directly from an array (rather than a Buffer) - thanks for the info.