glGetBufferPointerv — return the pointer to a mapped buffer object's data store
void glGetBufferPointerv( | GLenum | target, | 
| GLenum | pname, | |
| GLvoid ** | params); | 
target
                    Specifies the target buffer object.
                    The symbolic constant must be GL_ARRAY_BUFFER, 
                    GL_ELEMENT_ARRAY_BUFFER,
                    GL_PIXEL_PACK_BUFFER, or
                    GL_PIXEL_UNPACK_BUFFER.
                
pname
                    Specifies the pointer to be returned.  The symbolic constant must be GL_BUFFER_MAP_POINTER.
                
params
                    Returns the pointer value specified by pname.
                
            glGetBufferPointerv returns pointer information. pname is a symbolic constant
            indicating the pointer to be returned, which must be GL_BUFFER_MAP_POINTER, the pointer
            to which the buffer object's data store is mapped.  If the data store is not currently mapped, NULL is returned.
            params is a pointer to a location in which to place the returned pointer value.
        
            If an error is generated,
            no change is made to the contents of params.
        
            glGetBufferPointerv is available only if the GL version is 1.5 or greater.
        
            Targets GL_PIXEL_PACK_BUFFER and GL_PIXEL_UNPACK_BUFFER are available 
            only if the GL version is 2.1 or greater.
        
            The initial value for the pointer is NULL.
        
            GL_INVALID_ENUM is generated if target or pname is not an
            accepted value.
        
            GL_INVALID_OPERATION is generated if the reserved buffer object name 0 is bound to target.
        
            GL_INVALID_OPERATION is generated if glGetBufferPointerv
            is executed between the execution of glBegin
            and the corresponding execution of glEnd.
        
Copyright © 2005 Addison-Wesley. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.