Package pyglet.graphics

Low-level graphics rendering.

This module provides an efficient low-level abstraction over OpenGL. It gives very good performance for rendering OpenGL primitives; far better than the typical immediate-mode usage and, on modern graphics cards, better than using display lists in many cases. The module is used internally by other areas of pyglet.

See the Programming Guide for details on how to use this graphics API.

Batches and groups

Without even needing to understand the details on how to draw primitives with the graphics API, developers can make use of Batch and Group objects to improve performance of sprite and text rendering.

The Sprite, Label and TextLayout classes all accept a batch and group parameter in their constructors. A batch manages a set of objects that will be drawn all at once, and a group describes the manner in which an object is drawn.

The following example creates a batch, adds two sprites to the batch, and then draws the entire batch:

batch = pyglet.graphics.Batch()
car = pyglet.sprite.Sprite(car_image, batch=batch)
boat = pyglet.sprite.Sprite(boat_image, batch=batch)

def on_draw()
    batch.draw()

Drawing a complete batch is much faster than drawing the items in the batch individually, especially when those items belong to a common group.

Groups describe the OpenGL state required for an item. This is for the most part managed by the sprite and text classes, however you can also use groups to ensure items are drawn in a particular order. For example, the following example adds a background sprite which is guaranteed to be drawn before the car and the boat:

batch = pyglet.graphics.Batch()
background = pyglet.graphics.OrderedGroup(0)
foreground = pyglet.graphics.OrderedGroup(1)

background = pyglet.sprite.Sprite(background_image,
                                  batch=batch, group=background)
car = pyglet.sprite.Sprite(car_image, batch=batch, group=foreground)
boat = pyglet.sprite.Sprite(boat_image, batch=batch, group=foreground)

def on_draw()
    batch.draw()

It's preferable to manage sprites and text objects within as few batches as possible. If the drawing of sprites or text objects need to be interleaved with other drawing that does not use the graphics API, multiple batches will be required.

Data item parameters

Many of the functions and methods in this module accept any number of data parameters as their final parameters. In the documentation these are notated as *data in the formal parameter list.

A data parameter describes a vertex attribute format and an optional sequence to initialise that attribute. Examples of common attribute formats are:

"v3f"
Vertex position, specified as three floats.
"c4B"
Vertex color, specifed as four unsigned bytes.
"t2f"
Texture coordinate, specified as two floats.

See pyglet.graphics.vertexattribute for the complete syntax of the vertex format string.

When no initial data is to be given, the data item is just the format string. For example, the following creates a 2 element vertex list with position and color attributes:

vertex_list = pyglet.graphics.vertex_list(2, 'v2f', 'c4B')

When initial data is required, wrap the format string and the initial data in a tuple, for example:

vertex_list = pyglet.graphics.vertex_list(2,
                                          ('v2f', (0.0, 1.0, 1.0, 0.0)),
                                          ('c4B', (255, 255, 255, 255) * 2))

Drawing modes

Methods in this module that accept a mode parameter will accept any value in the OpenGL drawing mode enumeration; for example, GL_POINTS, GL_LINES, GL_TRIANGLES, etc.

Because of the way the graphics API renders multiple primitives with shared state, GL_POLYGON, GL_LINE_LOOP and GL_TRIANGLE_FAN cannot be used --- the results are undefined.

When using GL_LINE_STRIP, GL_TRIANGLE_STRIP or GL_QUAD_STRIP care must be taken to insert degenrate vertices at the beginning and end of each vertex list. For example, given the vertex list:

A, B, C, D

the correct vertex list to provide the vertex list is:

A, A, B, C, D, D

Alternatively, the NV_primitive_restart extension can be used if it is present. This also permits use of GL_POLYGON, GL_LINE_LOOP and GL_TRIANGLE_FAN. Unfortunatley the extension is not provided by older video drivers, and requires indexed vertex lists.

Since: pyglet 1.1

Submodules

pyglet.graphics.allocation
Memory allocation algorithm for vertex arrays and buffers.
pyglet.graphics.vertexattribute
Access byte arrays as arrays of vertex attributes.
pyglet.graphics.vertexbuffer
Byte abstractions of Vertex Buffer Objects and vertex arrays.
pyglet.graphics.vertexdomain
Manage related vertex attributes within a single vertex domain.

Classes

  Batch
Manage a collection of vertex lists for batched rendering.
  Group
Group of common OpenGL state.
  NullGroup
The default group class used when None is given to a batch.
  TextureGroup
A group that enables and binds a texture.
  OrderedGroup
A group with partial order.

Functions

  draw(size, mode, *data)
Draw a primitive immediately.
  draw_indexed(size, mode, indices, *data)
Draw a primitive with indexed vertices immediately.
VertexList vertex_list(count, *data)
Create a VertexList not associated with a batch, group or mode.
IndexedVertexList vertex_list_indexed(count, indices, *data)
Create an IndexedVertexList not associated with a batch, group or mode.

Variables

Group null_group = NullGroup()
The default group.

Function Details

draw

draw(size, mode, *data)
Draw a primitive immediately.
Parameters:
size : int
Number of vertices given
mode : int
OpenGL drawing mode, e.g. GL_TRIANGLES
data : data items
Attribute formats and data. See the module summary for details.

draw_indexed

draw_indexed(size, mode, indices, *data)
Draw a primitive with indexed vertices immediately.
Parameters:
size : int
Number of vertices given
mode : int
OpenGL drawing mode, e.g. GL_TRIANGLES
indices : sequence of int
Sequence of integers giving indices into the vertex list.
data : data items
Attribute formats and data. See the module summary for details.

vertex_list

vertex_list(count, *data)
Create a VertexList not associated with a batch, group or mode.
Parameters:
count : int
The number of vertices in the list.
data : data items
Attribute formats and initial data for the vertex list. See the module summary for details.
Returns: VertexList

vertex_list_indexed

vertex_list_indexed(count, indices, *data)
Create an IndexedVertexList not associated with a batch, group or mode.
Parameters:
count : int
The number of vertices in the list.
indices : sequence
Sequence of integers giving indices into the vertex list.
data : data items
Attribute formats and initial data for the vertex list. See the module summary for details.
Returns: IndexedVertexList