pyglet.graphics.vertexattribute

Access byte arrays as arrays of vertex attributes.

Use create_attribute() to create an attribute accessor given a simple format string. Alternatively, the classes may be constructed directly.

Attribute format strings

An attribute format string specifies the format of a vertex attribute. Format strings are accepted by the create_attribute() function as well as most methods in the pyglet.graphics module.

Format strings have the following (BNF) syntax:

attribute ::= ( name | index 'g' 'n'? | texture 't' ) count type

name describes the vertex attribute, and is one of the following constants for the predefined attributes:

c

Vertex color

e

Edge flag

f

Fog coordinate

n

Normal vector

s

Secondary color

t

Texture coordinate

v

Vertex coordinate

You can alternatively create a generic indexed vertex attribute by specifying its index in decimal followed by the constant g. For example, 0g specifies the generic vertex attribute with index 0. If the optional constant n is present after the g, the attribute is normalised to the range [0, 1] or [-1, 1] within the range of the data type.

Texture coordinates for multiple texture units can be specified with the texture number before the constant ‘t’. For example, 1t gives the texture coordinate attribute for texture unit 1.

count gives the number of data components in the attribute. For example, a 3D vertex position has a count of 3. Some attributes constrain the possible counts that can be used; for example, a normal vector must have a count of 3.

type gives the data type of each component of the attribute. The following types can be used:

b

GLbyte

B

GLubyte

s

GLshort

S

GLushort

i

GLint

I

GLuint

f

GLfloat

d

GLdouble

Some attributes constrain the possible data types; for example, normal vectors must use one of the signed data types. The use of some data types, while not illegal, may have severe performance concerns. For example, the use of GLdouble is discouraged, and colours should be specified with GLubyte.

Whitespace is prohibited within the format string.

Some examples follow:

v3f

3-float vertex position

c4b

4-byte colour

1eb

Edge flag

0g3f

3-float generic vertex attribute 0

1gn1i

Integer generic vertex attribute 1, normalized to [-1, 1]

2gn4B

4-byte generic vertex attribute 2, normalized to [0, 1] (because the type is unsigned)

3t2f

2-float texture coordinate for texture unit 3.

class AbstractAttribute(count, gl_type)

Abstract accessor for an attribute in a mapped buffer.

enable()

Enable the attribute using glEnableClientState.

get_region(buffer, start, count)

Map a buffer region using this attribute as an accessor.

The returned region can be modified as if the buffer was a contiguous array of this attribute (though it may actually be interleaved or otherwise non-contiguous).

The returned region consists of a contiguous array of component data elements. For example, if this attribute uses 3 floats per vertex, and the count parameter is 4, the number of floats mapped will be 3 * 4 = 12.

Parameters:

• buffer (AbstractMappable) – The buffer to map.
• start (int) – Offset of the first vertex to map.
• count (int) – Number of vertices to map

Return type:

AbstractBufferRegion

set_pointer(offset)

Setup this attribute to point to the currently bound buffer at the given offset.

offset should be based on the currently bound buffer’s ptr member.

Parameters:offset (int) – Pointer offset to the currently bound buffer for this attribute.

set_region(buffer, start, count, data)

Set the data over a region of the buffer.

Parameters:

• buffer (AbstractMappable) – The buffer to modify.
• start (int) – Offset of the first vertex to set.
• count (int) – Number of vertices to set.
• data (sequence) – Sequence of data components.

class ColorAttribute(count, gl_type)

Color vertex attribute.

enable()

set_pointer(pointer)

plural = ‘colors’

class EdgeFlagAttribute(gl_type)

Edge flag attribute.

enable()

set_pointer(pointer)

plural = ‘edge_flags’

class FogCoordAttribute(count, gl_type)

Fog coordinate attribute.

enable()

set_pointer(pointer)

plural = ‘fog_coords’

class GenericAttribute(index, normalized, count, gl_type)

Generic vertex attribute, used by shader programs.

enable()

set_pointer(pointer)

class MultiTexCoordAttribute(texture, count, gl_type)

Texture coordinate attribute.

enable()

set_pointer(pointer)

class NormalAttribute(gl_type)

Normal vector attribute.

enable()

set_pointer(pointer)

plural = ‘normals’

class SecondaryColorAttribute(gl_type)

Secondary color attribute.

enable()

set_pointer(pointer)

plural = ‘secondary_colors’

class TexCoordAttribute(count, gl_type)

Texture coordinate attribute.

convert_to_multi_tex_coord_attribute()

Changes the class of the attribute to MultiTexCoordAttribute.

enable()

set_pointer(pointer)

plural = ‘tex_coords’

class VertexAttribute(count, gl_type)

Vertex coordinate attribute.

enable()

set_pointer(pointer)

plural = ‘vertices’

create_attribute(format)

Create a vertex attribute description from a format string.

The initial stride and offset of the attribute will be 0.

Parameters:format (str) – Attribute format string. See the module summary for details. Return type:AbstractAttribute

interleave_attributes(attributes)

Interleave attribute offsets.

Adjusts the offsets and strides of the given attributes so that they are interleaved. Alignment constraints are respected.

Parameters:attributes (sequence of AbstractAttribute) – Attributes to interleave in-place.

serialize_attributes(count, attributes)

Serialize attribute offsets.

Adjust the offsets of the given attributes so that they are packed serially against each other for count vertices.

Parameters:

• count (int) – Number of vertices.
• attributes (sequence of AbstractAttribute) – Attributes to serialize in-place.