glGenVertexArrays

glGenVertexArrays is an OpenGL function used to generate vertex array object (VAO) names. It takes two parameters: the number of VAO names to generate (n) and a pointer to an array (arrays) where the generated names will be stored. The function writes n new, unused VAO identifiers into the provided array. The generated names are non-zero and can be used as handles to VAOs within the current OpenGL context.

The vertex array object is a container for state related to vertex data input. When a VAO is bound with glBindVertexArray, subsequent configuration commands store their state in that VAO instead of in the global context. This includes vertex attribute enablement and pointers (glEnableVertexAttribArray, glVertexAttribPointer), as well as the bindings of buffer objects (for example, GL_ARRAY_BUFFER) and element array buffers that are associated with the VAO. The actual vertex data resides in buffer objects; the VAO stores references to those buffers and the interpretation of their data.

After generation, a VAO must be bound before it can be configured or used for drawing. To render with a VAO, bind it with glBindVertexArray and issue drawing commands (such as glDrawArrays or glDrawElements). When a VAO is no longer needed, it can be deleted with glDeleteVertexArrays, which releases the associated resources. The names become invalid after deletion and may be generated again later.

GenVertexArrays originated from the ARB_vertex_array_object extension and is part of OpenGL core in version 3.0 and later. In modern OpenGL (and in OpenGL ES 3.0+), VAOs enable encapsulation of vertex input state, allowing multiple configurations to be swapped with minimal overhead. Some newer functions, such as glCreateVertexArrays (OpenGL 4.5+), offer alternatives for generating arrays of VAO names in a single call.