ddg.datastructures.halfedge.io module

class ddg.datastructures.halfedge.io.HalfedgeEncoder(vertex_attrs=[], edge_attrs=[], face_attrs=[], **kwargs)

Bases: JSONEncoder

default(obj)

Implement this method in a subclass such that it returns a serializable object for o, or calls the base implementation (to raise a TypeError).

For example, to support arbitrary iterators, you could implement default like this:

def default(self, o):
    try:
        iterable = iter(o)
    except TypeError:
        pass
    else:
        return list(iterable)
    # Let the base class default method raise the TypeError
    return JSONEncoder.default(self, o)

encode(o)

Return a JSON string representation of a Python data structure.

>>> from json.encoder import JSONEncoder
>>> JSONEncoder().encode({"foo": ["bar", "baz"]})
'{"foo": ["bar", "baz"]}'

item_separator = ', '

iterencode(o, _one_shot=False)

Encode the given object and yield each string representation as available.

For example:

for chunk in JSONEncoder().iterencode(bigobject):
    mysocket.write(chunk)

key_separator = ': '

ddg.datastructures.halfedge.io.to_json_string(surface, vertex_attrs=[], edge_attrs=[], face_attrs=[], write_index=False)

Create a json string from a given halfedge surface. Additional attributes to be included in the json string need to be specified explicitly in the respective dictionaries. All the references to vertices, edges, and faces are realized using integer indices. The None face corresponds to -1

Parameters:

surfacehalfedge surface

The surface to be converted to a json string

vertex_attrslist of strings

vertex attributes to be contained in the json string in addition to edge

edge_attrs

edge attributes to be contained in the json string in addition to pre, nex, opp, head, face

face_attrs

face attributes to be contained in the json string in addition to edge

Returns:

string

ddg.datastructures.halfedge.io.write_json_file(surface, filename, vertex_attrs=[], edge_attrs=[], face_attrs=[])

Create a file in json format from a given halfedge surface. Additional attributes to be included in the json string need to be specified explicitly in the respective dictionaries. All the references to vertices, edges, and faces are realized using integer indices. The None face corresponds to -1

Parameters:

surfacehalfedge surface

The surface to be converted to a json string

filenamestring

file to be written

vertex_attrslist of strings

vertex attributes to be contained in the json string in addition to edge

edge_attrs

edge attributes to be contained in the json string in addition to pre, nex, opp, head, face

face_attrs

face attributes to be contained in the json string in addition to edge

ddg.datastructures.halfedge.io.read_json_file(filename)

Create a surface from a json file. All keys will be mapped to respective attribute of the vertices, edges, and faces.

Parameters:

filename: string

file containing a json representing a halfedge surface

Returns:

surface

Raises:

ValueError

If required attributes are missing in the json string

ddg.datastructures.halfedge.io.parse_json_string(json_string)

Create a surface from a json string. All keys will be mapped to respective attribute of the vertices, edges, and faces.

Parameters:

json_stringstring

formatted string containing a halfedge surface

Returns:

surface

Raises:

ValueError

If required attributes are missing in the json string

ddg.datastructures.halfedge.io.surface_to_ifs_json(surface, vertex_attrs=['co'])

class ddg.datastructures.halfedge.io.SurfaceToIFSEncoder(vertex_attrs=['co'], **kwargs)

Bases: JSONEncoder

default(surface)

Implement this method in a subclass such that it returns a serializable object for o, or calls the base implementation (to raise a TypeError).

For example, to support arbitrary iterators, you could implement default like this:

def default(self, o):
    try:
        iterable = iter(o)
    except TypeError:
        pass
    else:
        return list(iterable)
    # Let the base class default method raise the TypeError
    return JSONEncoder.default(self, o)

encode(o)

Return a JSON string representation of a Python data structure.

>>> from json.encoder import JSONEncoder
>>> JSONEncoder().encode({"foo": ["bar", "baz"]})
'{"foo": ["bar", "baz"]}'

item_separator = ', '

iterencode(o, _one_shot=False)

Encode the given object and yield each string representation as available.

For example:

for chunk in JSONEncoder().iterencode(bigobject):
    mysocket.write(chunk)

key_separator = ': '

class ddg.datastructures.halfedge.io.ObjEncoder(filename)

Bases: object

Class to convert obj file to a ddg.halfedge.Surface or an IndexedFaceSet.

self.indexedfs is an IndexedFaceSet constructed of the obj file. self.halfedgeds is a Surface with halfedge attributes “vt” and “vn” (if given).

initialize_indexedfs()

Creates an IndexedFaceSet as self.indexedfs of the given obj file.

initialize_halfedgeds()

Creates a surface as self.halfedgeds of the given obj file.

Sets attributes “vn” and “vt” to edges pointing to the corresponding vertex if given.

ddg.datastructures.halfedge.io.obj_to_ifs(filename)

Converts an obj file to an IndexedFaceSet.

Parameters:

filename: (path and) name of the obj file

Returns:

IndexedFaceSet specified by the given obj file

ddg.datastructures.halfedge.io.obj_to_surface(filename)

Converts an obj file to a Surface with halfedge attributes “vt” and “vn”

(if given).

Obj file with given v and faces of the form f 1 2 3

or given v,vt and faces of the form f 1/1 2/1 3/1

or given v,vn and faces of the form f 1//1 2//1 3//1

or given v,vt,vn and faces of the form f 1/1/2 2/1/2 3/1/2.

Parameters:

filename: (path and) name of the obj file

Returns:

Surface specified by the given obj file

class ddg.datastructures.halfedge.io.SurfaceToObjEncoder(surface, filename='obj_file.obj', co_attr='co')

Bases: object

Class to convert a ddg.halfedge.Surface or an IndexedFaceSet to an obj file.

self.hds encodes the given surface.

write_obj()

ddg.datastructures.halfedge.io.surface_to_obj(surface, filename='obj_file.obj', co_attr='co')

Converts a ddg.halfedge.Surface to an obj file.

If ‘vn’ and/or ‘vt’ are given as halfegde attributes, they will be

written in the obj file format.

The vertices need to have coordinates, by default as the attribute ‘co’.

Results in Obj file with given v and faces of the form f 1 2 3

or given v,vt and faces of the form f 1/1 2/1 3/1

or given v,vn and faces of the form f 1//1 2//1 3//1

or given v,vt,vn and faces of the form f 1/1/2 2/1/2 3/1/2.

Vertices will be ordered by indices and vt and vn coordinates in increasing order.

Parameters:

surface: ddg.halfedge.Surface

halfedge data structure to be converted

filenamestr (default=’obj_file.obj’)

Name for the resulting obj file a file path can be specified here default is ‘obj_file’ which will be saved in the cwd

co_attrstr (default=’co’)

string of the vertx attribute that encodes the coordinates

Notes

• Indexing in obj files starts at 1.