1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
Spline
======
.. module:: ezdxf.entities
:noindex:
The SPLINE entity (`DXF Reference`_) is a 3D curve, all coordinates have to be 3D
coordinates even if the spline is just a 2D planar curve.
The spline curve is defined by control points, knot values and weights. The
control points establish the spline, the various types of knot vector determines
the shape of the curve and the weights of rational splines define how
strong a control point influences the shape.
A SPLINE can be created just from fit points - knot values and weights are
optional (tested with AutoCAD 2010). If you add additional data,
be sure you know what you do, because invalid data may invalidate
the whole DXF file.
The function :func:`ezdxf.math.fit_points_to_cad_cv` calculates control
vertices from given fit points. This control vertices define a cubic
B-spline which matches visually the SPLINE entities created by BricsCAD and
AutoCAD from fit points.
.. seealso::
- `Wikipedia`_ article about B_splines
- Department of Computer Science and Technology at the `Cambridge`_ University
- :ref:`tut_spline`
======================== ==========================================
Subclass of :class:`ezdxf.entities.DXFGraphic`
DXF type ``'SPLINE'``
Factory function see table below
Inherited DXF attributes :ref:`Common graphical DXF attributes`
Required DXF version DXF R2000 (``'AC1015'``)
======================== ==========================================
Factory Functions
-----------------
=========================================== ==========================================
Basic spline entity :meth:`~ezdxf.layouts.BaseLayout.add_spline`
Spline control frame from fit points :meth:`~ezdxf.layouts.BaseLayout.add_spline_control_frame`
Open uniform spline :meth:`~ezdxf.layouts.BaseLayout.add_open_spline`
Closed uniform spline :meth:`~ezdxf.layouts.BaseLayout.add_closed_spline`
Open rational uniform spline :meth:`~ezdxf.layouts.BaseLayout.add_rational_spline`
Closed rational uniform spline :meth:`~ezdxf.layouts.BaseLayout.add_closed_rational_spline`
=========================================== ==========================================
.. _DXF Reference: http://help.autodesk.com/view/OARX/2018/ENU/?guid=GUID-E1F884F8-AA90-4864-A215-3182D47A9C74
.. class:: Spline
All points in :ref:`WCS` as (x, y, z) tuples
.. attribute:: dxf.degree
Degree of the spline curve (int).
.. attribute:: dxf.flags
Bit coded option flags, constants defined in :mod:`ezdxf.lldxf.const`:
=================== ======= ===========
dxf.flags Value Description
=================== ======= ===========
CLOSED_SPLINE 1 Spline is closed
PERIODIC_SPLINE 2
RATIONAL_SPLINE 4
PLANAR_SPLINE 8
LINEAR_SPLINE 16 planar bit is also set
=================== ======= ===========
.. attribute:: dxf.n_knots
Count of knot values (int), automatically set by `ezdxf` (read only)
.. attribute:: dxf.n_fit_points
Count of fit points (int), automatically set by ezdxf (read only)
.. attribute:: dxf.n_control_points
Count of control points (int), automatically set by ezdxf (read only)
.. attribute:: dxf.knot_tolerance
Knot tolerance (float); default is 1e-10
.. attribute:: dxf.fit_tolerance
Fit tolerance (float); default is 1e-10
.. attribute:: dxf.control_point_tolerance
Control point tolerance (float); default is 1e-10
.. attribute:: dxf.start_tangent
Start tangent vector as 3D vector in :ref:`WCS`
.. attribute:: dxf.end_tangent
End tangent vector as 3D vector in :ref:`WCS`
.. autoattribute:: closed
.. autoattribute:: control_points
.. autoattribute:: fit_points
.. autoattribute:: knots
.. autoattribute:: weights
.. automethod:: control_point_count
.. automethod:: fit_point_count
.. automethod:: knot_count
.. automethod:: construction_tool
.. automethod:: apply_construction_tool
.. automethod:: flattening
.. automethod:: set_open_uniform
.. automethod:: set_uniform
.. automethod:: set_closed
.. automethod:: set_open_rational
.. automethod:: set_uniform_rational
.. automethod:: set_closed_rational
.. automethod:: transform
.. automethod:: from_arc
.. _Cambridge: https://www.cl.cam.ac.uk/teaching/2000/AGraphHCI/SMEG/node4.html
.. _Wikipedia: https://en.wikipedia.org/wiki/Spline_%28mathematics%29
|
