An object that behaves like a T[] (or const(T)[], for the read-only version), and reflects the contents of the Vbo. After this object is destructed, slices in that piece of memory are no longer valid (because glUnmapBuffer is then called).
auto v = Vbo!int(3); { auto m = v.mapWriteOnly(); m[] = 5; m[1] = 2; } assert(v.mapReadOnly()[] == [5, 2, 5]);
Map the contents of the Vbo in our own memory, temporarily. (Calls glMapBuffer.)