Vao

VAO stands for Vertex Array Object in computer graphics, particularly within the OpenGL API. A VAO is an object that stores the state needed to describe how vertex data is read by the vertex shader. The VAO itself does not contain vertex data; instead, it records how to fetch vertex attributes from one or more Vertex Buffer Objects (VBOs) and, if used, how indices are read from an Element Buffer Object (EBO).

To use a VAO, developers generate it with glGenVertexArrays, bind it with glBindVertexArray, and then configure the vertex attributes. Each attribute is described with glVertexAttribPointer and enabled with glEnableVertexAttribArray. The VBO containing the attribute data is bound while the VAO is bound, and, if indexed rendering is used, the EBO is bound as the GL_ELEMENT_ARRAY_BUFFER. The state captured by the VAO includes the bindings and attribute configurations.

During rendering, the application binds the desired VAO and issues a draw call such as glDrawArrays or glDrawElements. Binding a VAO restores the stored attribute configuration and bindings, so subsequent draw calls reuse the setup without re-specifying each attribute. Multiple VAOs may be used to represent different meshes with different attribute layouts.

In modern OpenGL, VAOs are commonly required for core profile contexts and help reduce the cost of repeated state changes. They do not store the actual vertex data, shader programs, textures, or other non-VAO state; these must be bound separately. The number of VAOs available is limited by the implementation.

Other meanings of VAO exist in different domains, but this article describes the Vertex Array Object in OpenGL.