Provided by: allegro5-doc_5.2.9.1+dfsg-1.1build4_all 
      
    
NAME
       al_lock_vertex_buffer - Allegro 5 API
SYNOPSIS
              #include <allegro5/allegro_primitives.h>
              void* al_lock_vertex_buffer(ALLEGRO_VERTEX_BUFFER* buffer, int offset,
                 int length, int flags)
DESCRIPTION
       Locks  a  vertex  buffer  so you can access its data.  Will return NULL if the parameters are invalid, if
       reading is requested from a write only buffer, or if the buffer is already locked.
       Parameters:
       • buffer - Vertex buffer to lock
       • offset - Vertex index of the start of the locked range
       • length - How many vertices to lock
       • flags - ALLEGRO_LOCK_READONLY, ALLEGRO_LOCK_WRITEONLY or ALLEGRO_LOCK_READWRITE
SINCE
       5.1.3
SEE ALSO
       ALLEGRO_VERTEX_BUFFER(3alleg5), al_unlock_vertex_buffer(3alleg5)
Allegro reference manual                                                          al_lock_vertex_buffer(3alleg5)