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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
// plarc()
//
// Copyright (C) 2009 Hezekiah M. Carty
//
// This file is part of PLplot.
//
// PLplot is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published
// by the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// PLplot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with PLplot; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
//! @file
//! Functions for drawing an arc.
//!
#include "plplotP.h"
#define CIRCLE_SEGMENTS ( PL_MAXPOLY - 1 )
#define DEG_TO_RAD( x ) ( ( x ) * M_PI / 180.0 )
void plarc_approx( PLFLT x, PLFLT y, PLFLT a, PLFLT b, PLFLT angle1, PLFLT angle2, PLFLT rotate, PLBOOL fill );
//--------------------------------------------------------------------------
// plarc_approx : Plot an approximated arc with a series of lines
//
//! Takes the same arguments, with the same units, as c_plarc below.
//! This is the fallback function in the event that the output
//! device does not have native support for drawing arcs.
//!
//! @param x Center coordinate of the arc in x.
//! @param y Center coordinate of the arc in y.
//! @param a Radius of the arcs major axis.
//! @param b Radius of the arcs minor axis.
//! @param angle1 Start angle in degrees.
//! @param angle2 End angle in degrees.
//! @param rotate How much to rotate the arc?
//! @param fill Fill the arc.
//!
//--------------------------------------------------------------------------
void
plarc_approx( PLFLT x, PLFLT y, PLFLT a, PLFLT b, PLFLT angle1, PLFLT angle2, PLFLT rotate, PLBOOL fill )
{
PLINT i;
PLFLT theta0, theta_step, theta, d_angle;
PLINT segments;
PLFLT xs[CIRCLE_SEGMENTS + 1], ys[CIRCLE_SEGMENTS + 1];
PLFLT cphi, sphi, ctheta, stheta;
// The difference between the start and end angles
d_angle = DEG_TO_RAD( angle2 - angle1 );
if ( fabs( d_angle ) > M_PI * 2.0 )
d_angle = M_PI * 2.0;
// Calculate cosine and sine of angle of major axis wrt the x axis
cphi = cos( DEG_TO_RAD( rotate ) );
sphi = sin( DEG_TO_RAD( rotate ) );
// The number of line segments used to approximate the arc
segments = (PLINT) ( fabs( d_angle ) / ( 2.0 * M_PI ) * CIRCLE_SEGMENTS );
// Always use at least 2 arc points, otherwise fills will break.
if ( segments < 2 )
segments = 2;
// The start angle in radians and number of radians in each approximating
// segment.
theta0 = DEG_TO_RAD( angle1 );
theta_step = d_angle / ( segments - 1 );
// The coordinates for the circle outline
for ( i = 0; i < segments; i++ )
{
theta = theta0 + theta_step * (PLFLT) i;
ctheta = cos( theta );
stheta = sin( theta );
xs[i] = x + a * ctheta * cphi - b * stheta * sphi;
ys[i] = y + a * ctheta * sphi + b * stheta * cphi;
}
if ( fill )
{
// Add the center point if we aren't drawing a circle
if ( fabs( d_angle ) < M_PI * 2.0 )
{
xs[segments] = x;
ys[segments] = y;
segments++;
}
// Draw a filled arc
plfill( segments, xs, ys );
}
else
{
// Draw the arc outline
plline( segments, xs, ys );
}
}
//--------------------------------------------------------------------------
// plarc : Plot an arc
//
//! Plot an Arc.
//! Takes the following arguments:
//!
//! x, y:
//! x and y coordinates for the center of the arc
//!
//! a, b:
//! Radius of the arc's major and minor axes
//!
//! angle1:
//! Start angle (degrees)
//!
//! angle2:
//! End angle (degrees)
//!
//! fill:
//! Should the arc be filled
//!
//! @param x Center coordinate of the arc in x.
//! @param y Center coordinate of the arc in y.
//! @param a Radius of the arcs major axis.
//! @param b Radius of the arcs minor axis.
//! @param angle1 Start angle in degrees.
//! @param angle2 End angle in degrees.
//! @param rotate How much to rotate the arc?
//! @param fill Fill the arc.
//!
//
//--------------------------------------------------------------------------
void
c_plarc( PLFLT x, PLFLT y, PLFLT a, PLFLT b, PLFLT angle1, PLFLT angle2, PLFLT rotate, PLBOOL fill )
{
PLINT xscl[2], yscl[2];
PLINT clpxmi, clpxma, clpymi, clpyma;
arc_struct *arc_info;
// TODO: For now, only unrotated plots use the driver-accelerated path.
if ( plsc->dev_arc && plsc->diorot == 0 )
{
arc_info = (arc_struct *) malloc( (size_t) sizeof ( arc_struct ) );
xscl[0] = plP_wcpcx( x - a );
xscl[1] = plP_wcpcx( x + a );
yscl[0] = plP_wcpcy( y - b );
yscl[1] = plP_wcpcy( y + b );
difilt( xscl, yscl, 2, &clpxmi, &clpxma, &clpymi, &clpyma );
arc_info->x = 0.5 * ( xscl[1] + xscl[0] );
arc_info->y = 0.5 * ( yscl[1] + yscl[0] );
arc_info->a = 0.5 * ( xscl[1] - xscl[0] );
arc_info->b = 0.5 * ( yscl[1] - yscl[0] );
arc_info->angle1 = angle1;
arc_info->angle2 = angle2;
arc_info->rotate = rotate;
arc_info->fill = fill;
plP_esc( PLESC_ARC, arc_info );
free( arc_info );
}
else
{
plarc_approx( x, y, a, b, angle1, angle2, rotate, fill );
}
}
|
