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# -*- coding: utf-8 -*-
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
"""
Simple ellipse visual based on PolygonVisual
"""
from __future__ import division
import numpy as np
from .polygon import PolygonVisual
class EllipseVisual(PolygonVisual):
"""
Displays a 2D ellipse
Parameters
----------
center : array
Center of the ellipse
color : instance of Color
The face color to use.
border_color : instance of Color
The border color to use.
border_width: float
The width of the border in pixels
Line widths > 1px are only
guaranteed to work when using `border_method='agg'` method.
radius : float | tuple
Radius or radii of the ellipse
Defaults to (0.1, 0.1)
start_angle : float
Start angle of the ellipse in degrees
Defaults to 0.
span_angle : float
Span angle of the ellipse in degrees
Defaults to 360.
num_segments : int
Number of segments to be used to draw the ellipse
Defaults to 100
**kwargs : dict
Keyword arguments to pass to `PolygonVisual`.
"""
def __init__(self, center=None, color='black', border_color=None,
border_width=1, radius=(0.1, 0.1), start_angle=0.,
span_angle=360., num_segments=100, **kwargs):
self._center = center
self._radius = radius
self._start_angle = start_angle
self._span_angle = span_angle
self._num_segments = num_segments
# triangulation can be very slow
kwargs.setdefault('triangulate', False)
PolygonVisual.__init__(self, pos=None, color=color,
border_color=border_color,
border_width=border_width, **kwargs)
self._mesh.mode = "triangle_fan"
self._regen_pos()
self._update()
@staticmethod
def _generate_vertices(center, radius, start_angle, span_angle,
num_segments):
if isinstance(radius, (list, tuple)):
if len(radius) == 2:
xr, yr = radius
else:
raise ValueError("radius must be float or 2 value tuple/list"
" (got %s of length %d)" % (type(radius),
len(radius)))
else:
xr = yr = radius
start_angle = np.deg2rad(start_angle)
vertices = np.empty([num_segments + 2, 2], dtype=np.float32)
# split the total angle into num_segments intances
theta = np.linspace(start_angle,
start_angle + np.deg2rad(span_angle),
num_segments + 1)
# PolarProjection
vertices[1:, 0] = center[0] + xr * np.cos(theta)
vertices[1:, 1] = center[1] + yr * np.sin(theta)
# specify center point (not used in border)
vertices[0] = np.float32([center[0], center[1]])
return vertices
@property
def center(self):
""" The center of the ellipse
"""
return self._center
@center.setter
def center(self, center):
""" The center of the ellipse
"""
self._center = center
self._regen_pos()
self._update()
@property
def radius(self):
""" The start radii of the ellipse.
"""
return self._radius
@radius.setter
def radius(self, radius):
self._radius = radius
self._regen_pos()
self._update()
@property
def start_angle(self):
""" The start start_angle of the ellipse.
"""
return self._start_angle
@start_angle.setter
def start_angle(self, start_angle):
self._start_angle = start_angle
self._regen_pos()
self._update()
@property
def span_angle(self):
""" The angular span of the ellipse.
"""
return self._span_angle
@span_angle.setter
def span_angle(self, span_angle):
self._span_angle = span_angle
self._regen_pos()
self._update()
@property
def num_segments(self):
""" The number of segments in the ellipse.
"""
return self._num_segments
@num_segments.setter
def num_segments(self, num_segments):
num_segments = int(num_segments)
if num_segments < 1:
raise ValueError('EllipseVisual must consist of more than 1 '
'segment')
self._num_segments = num_segments
self._regen_pos()
self._update()
def _regen_pos(self):
vertices = self._generate_vertices(center=self._center,
radius=self._radius,
start_angle=self._start_angle,
span_angle=self._span_angle,
num_segments=self._num_segments)
# don't use the center point
self._pos = vertices[1:]
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