The name stack is used during selection mode to allow sets of rendering
commands to be uniquely identified.
It consists of an ordered set of unsigned integers and is initially empty.
glPushName causes name to be pushed onto the name stack.
glPopName pops one name off the top of the stack.
The maximum name stack depth is implementation-dependent; call
GL_MAX_NAME_STACK_DEPTH to find out the value for a particular
implementation. It is an
error to push a name onto a full stack,
or to pop a name off an empty stack.
It is also an error to manipulate the name stack between the execution of
glBegin and the corresponding execution of glEnd .
In any of these cases, the error flag is set and no other change is
made to GL state.
The name stack is always empty while the render mode is not GL_SELECT .
Calls to glPushName or glPopName while the render mode is not
GL_SELECT are ignored.
GL.glPopMatrix()