class moderngl_window.opengl.vao.VAO(name: str = '', mode: int = 4)

Represents a vertex array object.

This is a wrapper class over moderngl.VertexArray to make interactions with programs/shaders simpler. Named buffers are added corresponding with attribute names in a vertex shader. When rendering the VAO an internal moderngl.VertextArray is created automatically mapping the named buffers compatible with the supplied program. This program is cached internally.

The shader program doesn’t need to use all the buffers registered in this wrapper. When a subset is used only the used buffers are mapped and the appropriate padding is calculated when interleaved data is used.

You are not required to use this class, but most methods in the system creating vertexbuffers will return this type. You can obtain a single moderngl.VertexBuffer instance by calling VAO.instance() method if you prefer to work directly on moderngl instances.

Example:

# Separate buffers
vao = VAO(name="test", mode=moderngl.POINTS)
vao.buffer(positions, '3f', ['in_position'])
vao.buffer(velocities, '3f', ['in_velocities'])

# Interleaved
vao = VAO(name="test", mode=moderngl.POINTS)
vao.buffer(interleaved_data, '3f 3f', ['in_position', 'in_velocities'])

# GLSL vertex shader in attributes
in vec3 in_position;
in vec3 in_velocities;

buffer(buffer: Buffer | ndarray[tuple[Any, ...], dtype[Any]] | bytes, buffer_format: str, attribute_names: list[str] | str) → Buffer

Register a buffer/vbo for the VAO. This can be called multiple times. adding multiple buffers (interleaved or not).

Parameters:

• buffer – The buffer data. Can be numpy.array, moderngl.Buffer or bytes.

• buffer_format (str) – The format of the buffer. (eg. 3f 3f for interleaved positions and normals).

• attribute_names – A list of attribute names this buffer should map to.

Returns:

The moderngl.Buffer instance object. This is handy when providing bytes and numpy.array.

property ctx: Context

The active moderngl context

Type:

moderngl.Context

get_buffer_by_name(name: str) → BufferInfo | None

Get the BufferInfo associated with a specific attribute name

If no buffer is associated with the name None will be returned.

Parameters:

name (str) – Name of the mapped attribute

Returns:

BufferInfo instance

Return type:

BufferInfo

index_buffer(buffer: Buffer | ndarray[tuple[Any, ...], dtype[Any]] | bytes, index_element_size: int = 4) → None

Set the index buffer for this VAO.

Parameters:

buffer – moderngl.Buffer, numpy.array or bytes

Keyword Arguments:

index_element_size (int) – Byte size of each element. 1, 2 or 4

instance(program: Program) → VertexArray

Obtain the moderngl.VertexArray instance for the program.

The instance is only created once and cached internally.

Parameters:

program (moderngl.Program) – The program

Returns:

instance

Return type:

moderngl.VertexArray

release(buffer: bool = True) → None

Destroy all internally cached vaos and release all buffers.

Keyword Arguments:

buffers (bool) – also release buffers

render(program: Program, mode: int | None = None, vertices: int = -1, first: int = 0, instances: int = 1) → None

Render the VAO.

An internal moderngl.VertexBuffer with compatible buffer bindings is automatically created on the fly and cached internally.

Parameters:

program – The moderngl.Program

Keyword Arguments:

• mode – Override the draw mode (TRIANGLES etc)

• vertices (int) – The number of vertices to transform

• first (int) – The index of the first vertex to start with

• instances (int) – The number of instances

render_indirect(program: Program, buffer: Buffer, mode: int | None = None, count: int = -1, *, first: int = 0) → None

The render primitive (mode) must be the same as the input primitive of the GeometryShader.

The draw commands are 5 integers: (count, instanceCount, firstIndex, baseVertex, baseInstance).

Parameters:

• program – The moderngl.Program

• buffer – The moderngl.Buffer containing indirect draw commands

Keyword Arguments:

• mode (int) – By default TRIANGLES will be used.

• count (int) – The number of draws.

• first (int) – The index of the first indirect draw command.

transform(program: Program, buffer: Buffer, mode: int | None = None, vertices: int = -1, first: int = 0, instances: int = 1) → None

Transform vertices. Stores the output in a single buffer.

Parameters:

• program – The moderngl.Program

• buffer – The moderngl.buffer to store the output

Keyword Arguments:

• mode – Draw mode (for example moderngl.POINTS)

• vertices (int) – The number of vertices to transform

• first (int) – The index of the first vertex to start with

• instances (int) – The number of instances