I have a question on mapping buffers.
OpenGL normally guarantees the contents of objects. In the case of mapping a buffer, the buffer can be corrupted through acts of the Operating System.
I know that doing Alt-Tab on a WinXP or lower machine is license for Windows to stomp all over video memory. Presumably, if you have a buffer mapped at the moment someone does an Alt-Tab, you’ll lose the buffer’s data.
So my first question is: is this true?
Second question: under what other (non-GL error) circumstances will glUnmapBuffer return FALSE?
Third question: will glUnmapBuffer ever return FALSE on Vista or Win7 machines? I ask that because those OS’s have video memory protection that XP does not.
And a fourth question as an aside: since Vista/Win7 have video memory protections, do OpenGL implementations on those OS’s still keep a system-memory copy of textures and buffers?