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
|
//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.3
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//----------------------------------------------------------------------------
//
// Liang-Barsky clipping
//
//----------------------------------------------------------------------------
#ifndef AGG_CLIP_LIANG_BARSKY_INCLUDED
#define AGG_CLIP_LIANG_BARSKY_INCLUDED
#include "agg_basics.h"
namespace agg
{
template<class T>
inline unsigned clipping_flags(T x, T y, const rect_base<T>& clip_box)
{
return (x > clip_box.x2) |
((y > clip_box.y2) << 1) |
((x < clip_box.x1) << 2) |
((y < clip_box.y1) << 3);
}
template<class T>
inline unsigned clip_liang_barsky(T x1, T y1, T x2, T y2,
const rect_base<T>& clip_box,
T* x, T* y)
{
const FX_FLOAT nearzero = 1e-30f;
FX_FLOAT deltax = (FX_FLOAT)(x2 - x1);
FX_FLOAT deltay = (FX_FLOAT)(y2 - y1);
unsigned np = 0;
if(deltax == 0) {
deltax = (x1 > clip_box.x1) ? -nearzero : nearzero;
}
FX_FLOAT xin, xout;
if(deltax > 0) {
xin = (FX_FLOAT)clip_box.x1;
xout = (FX_FLOAT)clip_box.x2;
} else {
xin = (FX_FLOAT)clip_box.x2;
xout = (FX_FLOAT)clip_box.x1;
}
FX_FLOAT tinx = (xin - x1) / deltax;
if(deltay == 0) {
deltay = (y1 > clip_box.y1) ? -nearzero : nearzero;
}
FX_FLOAT yin, yout;
if(deltay > 0) {
yin = (FX_FLOAT)clip_box.y1;
yout = (FX_FLOAT)clip_box.y2;
} else {
yin = (FX_FLOAT)clip_box.y2;
yout = (FX_FLOAT)clip_box.y1;
}
FX_FLOAT tiny = (yin - y1) / deltay;
FX_FLOAT tin1, tin2;
if (tinx < tiny) {
tin1 = tinx;
tin2 = tiny;
} else {
tin1 = tiny;
tin2 = tinx;
}
if(tin1 <= 1.0f) {
if(0 < tin1) {
*x++ = (T)xin;
*y++ = (T)yin;
++np;
}
if(tin2 <= 1.0f) {
FX_FLOAT toutx = (xout - x1) / deltax;
FX_FLOAT touty = (yout - y1) / deltay;
FX_FLOAT tout1 = (toutx < touty) ? toutx : touty;
if (tin2 > 0 || tout1 > 0) {
if(tin2 <= tout1) {
if(tin2 > 0) {
if(tinx > tiny) {
*x++ = (T)xin;
*y++ = (T)(y1 + (deltay * tinx));
} else {
*x++ = (T)(x1 + (deltax * tiny));
*y++ = (T)yin;
}
++np;
}
if(tout1 < 1.0f) {
if(toutx < touty) {
*x++ = (T)xout;
*y++ = (T)(y1 + (deltay * toutx));
} else {
*x++ = (T)(x1 + (deltax * touty));
*y++ = (T)yout;
}
} else {
*x++ = x2;
*y++ = y2;
}
++np;
} else {
if(tinx > tiny) {
*x++ = (T)xin;
*y++ = (T)yout;
} else {
*x++ = (T)xout;
*y++ = (T)yin;
}
++np;
}
}
}
}
return np;
}
}
#endif
|
