VertexArray
- class moderngl.VertexArray
A VertexArray object is an OpenGL object that stores all of the state needed to supply vertex data.
It stores the format of the vertex data as well as the Buffer objects providing the vertex data arrays.
In ModernGL, the VertexArray object also stores a reference for a
Program
object, and some Subroutine information.A VertexArray object cannot be instantiated directly, it requires a context. Use
Context.vertex_array()
orContext.simple_vertex_array()
to create one.Note
Compared to OpenGL,
VertexArray
objects have some additional responsibilities:Binding a
Program
whenVertexArray.render()
orVertexArray.transform()
is called.Subroutines can be assigned. Please see the example below.
Create
- Context.simple_vertex_array(program: Program, buffer: Buffer, *attributes: Union[List[str], Tuple[str, ...]], index_buffer: Optional[Buffer] = None, index_element_size: int = 4, mode: Optional[int] = None) VertexArray
Create a
VertexArray
object.Warning
This method is deprecated and may be removed in the future. Use
Context.vertex_array()
instead. It also supports the argument format this method describes.- Parameters:
- Keyword Arguments:
index_element_size (int) – byte size of each index element, 1, 2 or 4.
index_buffer (Buffer) – An index buffer.
mode (int) – The default draw mode (for example:
TRIANGLES
)
- Returns:
VertexArray
object
- Context.vertex_array(*args, **kwargs) VertexArray
Create a
VertexArray
object.The vertex array describes how buffers are read by a shader program. We need to supply buffer formats and attributes names. The attribute names are defined by the user in the glsl code and can be anything.
Examples:
# Empty vertext array (no attribute input) vao = ctx.vertex_array(program) # Simple version with a single buffer vao = ctx.vertex_array(program, buffer, "in_position", "in_normal") vao = ctx.vertex_array(program, buffer, "in_position", "in_normal", index_buffer=ibo) # Multiple buffers vao = ctx.vertex_array(program, [ (buffer1, '3f', 'in_position'), (buffer2, '3f', 'in_normal'), ]) vao = ctx.vertex_array(program, [ (buffer1, '3f', 'in_position'), (buffer2, '3f', 'in_normal'), ], index_buffer=ibo, index_element_size=2, # 16 bit / 'u2' index buffer )
This method also supports arguments for
Context.simple_vertex_array()
.- Parameters:
program (Program) – The program used when rendering
content (list) – A list of (buffer, format, attributes). See Buffer Format.
- Keyword Arguments:
index_buffer (Buffer) – An index buffer (optional)
index_element_size (int) – byte size of each index element, 1, 2 or 4.
skip_errors (bool) – Ignore errors during creation
mode (int) – The default draw mode (for example:
TRIANGLES
)
- Returns:
VertexArray
object
Methods
- VertexArray.render(mode: Optional[int] = None, vertices: int = -1, *, first: int = 0, instances: int = -1) None
The render primitive (mode) must be the same as the input primitive of the GeometryShader.
- Parameters:
mode (int) – By default
TRIANGLES
will be used.vertices (int) – The number of vertices to transform.
- Keyword Arguments:
first (int) – The index of the first vertex to start with.
instances (int) – The number of instances.
- VertexArray.render_indirect(buffer: Buffer, mode: Optional[int] = 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).
- VertexArray.transform(buffer: Union[Buffer, List[Buffer]], mode: Optional[int] = None, vertices: int = -1, *, first: int = 0, instances: int = -1, buffer_offset: int = 0) None
Transform vertices.
Stores the output in a single buffer. The transform primitive (mode) must be the same as the input primitive of the GeometryShader.
- Parameters:
- Keyword Arguments:
first (int) – The index of the first vertex to start with.
instances (int) – The number of instances.
buffer_offset (int) – Byte offset for the output buffer
- VertexArray.bind(attribute: int, cls: str, buffer: Buffer, fmt: str, *, offset: int = 0, stride: int = 0, divisor: int = 0, normalize: bool = False) None
Bind individual attributes to buffers.
- Parameters:
location (int) – The attribute location.
cls (str) – The attribute class. Valid values are
f
,i
ord
.buffer (Buffer) – The buffer.
format (str) – The buffer format.
- Keyword Arguments:
offset (int) – The offset.
stride (int) – The stride.
divisor (int) – The divisor.
normalize (bool) – The normalize parameter, if applicable.
- VertexArray.release() None
Release the ModernGL object.
Attributes
- VertexArray.mode
Get or set the default rendering mode.
This value is used when
mode
is not passed in rendering calls.Examples:
vao.mode = moderngl.TRIANGLE_STRIPS
- Type:
int
- VertexArray.program
The program assigned to the VertexArray.
The program used when rendering or transforming primitives.
- Type:
- VertexArray.index_element_size
The byte size of each element in the index buffer.
- Type:
int
- VertexArray.scope
The
moderngl.Scope
.
- VertexArray.vertices
The number of vertices detected.
This is the minimum of the number of vertices possible per Buffer. The size of the index_buffer determines the number of vertices. Per instance vertex attributes does not affect this number.
- Type:
int
- VertexArray.instances
Get or set the number of instances to render.
- Type:
int
- VertexArray.subroutines
The subroutines assigned to the VertexArray.
The subroutines used when rendering or transforming primitives.
- Type:
tuple
- VertexArray.glo
The internal OpenGL object.
This values is provided for debug purposes only.
- Type:
int
- VertexArray.mglo
Internal representation for debug purposes only.
- VertexArray.extra
Any - Attribute for storing user defined objects
- VertexArray.ctx
The context this object belongs to