---
name: "al_lock_vertex_buffer"
section: "3"
platform: "linux"
package: "allegro"
version: "5.2.11.3-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/al_lock_vertex_buffer"
---

# al\_lock\_vertex\_buffer(3)

Allegro 5 API

## 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(3)](/ALLEGRO_VERTEX_BUFFER/3.md), [al\_unlock\_vertex\_buffer(3)](/al_unlock_vertex_buffer/3.md)