1
2//----------------------------------------------------------------------------
3// Anti-Grain Geometry - Version 2.3
4// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
5//
6// Permission to copy, use, modify, sell and distribute this software
7// is granted provided this copyright notice appears in all copies.
8// This software is provided "as is" without express or implied
9// warranty, and with no claim as to its suitability for any purpose.
10//
11//----------------------------------------------------------------------------
12// Contact: mcseem@antigrain.com
13//          mcseemagg@yahoo.com
14//          http://www.antigrain.com
15//----------------------------------------------------------------------------
16//
17// Liang-Barsky clipping
18//
19//----------------------------------------------------------------------------
20#ifndef AGG_CLIP_LIANG_BARSKY_INCLUDED
21#define AGG_CLIP_LIANG_BARSKY_INCLUDED
22#include "agg_basics.h"
23namespace agg
24{
25template<class T>
26inline unsigned clipping_flags(T x, T y, const rect_base<T>& clip_box)
27{
28    return  (x > clip_box.x2) |
29            ((y > clip_box.y2) << 1) |
30            ((x < clip_box.x1) << 2) |
31            ((y < clip_box.y1) << 3);
32}
33template<class T>
34inline unsigned clip_liang_barsky(T x1, T y1, T x2, T y2,
35                                  const rect_base<T>& clip_box,
36                                  T* x, T* y)
37{
38    const FX_FLOAT nearzero = 1e-30f;
39    FX_FLOAT deltax = (FX_FLOAT)(x2 - x1);
40    FX_FLOAT deltay = (FX_FLOAT)(y2 - y1);
41    unsigned np = 0;
42    if(deltax == 0) {
43        deltax = (x1 > clip_box.x1) ? -nearzero : nearzero;
44    }
45    FX_FLOAT xin, xout;
46    if(deltax > 0) {
47        xin  = (FX_FLOAT)clip_box.x1;
48        xout = (FX_FLOAT)clip_box.x2;
49    } else {
50        xin  = (FX_FLOAT)clip_box.x2;
51        xout = (FX_FLOAT)clip_box.x1;
52    }
53    FX_FLOAT tinx = FXSYS_Div(xin - x1, deltax);
54    if(deltay == 0) {
55        deltay = (y1 > clip_box.y1) ? -nearzero : nearzero;
56    }
57    FX_FLOAT yin, yout;
58    if(deltay > 0) {
59        yin  = (FX_FLOAT)clip_box.y1;
60        yout = (FX_FLOAT)clip_box.y2;
61    } else {
62        yin  = (FX_FLOAT)clip_box.y2;
63        yout = (FX_FLOAT)clip_box.y1;
64    }
65    FX_FLOAT tiny = FXSYS_Div(yin - y1, deltay);
66    FX_FLOAT tin1, tin2;
67    if (tinx < tiny) {
68        tin1 = tinx;
69        tin2 = tiny;
70    } else {
71        tin1 = tiny;
72        tin2 = tinx;
73    }
74    if(tin1 <= 1.0f) {
75        if(0 < tin1) {
76            *x++ = (T)xin;
77            *y++ = (T)yin;
78            ++np;
79        }
80        if(tin2 <= 1.0f) {
81            FX_FLOAT toutx = FXSYS_Div(xout - x1, deltax);
82            FX_FLOAT touty = FXSYS_Div(yout - y1, deltay);
83            FX_FLOAT tout1 = (toutx < touty) ? toutx : touty;
84            if(tin2 > 0 || tout1 > 0) {
85                if(tin2 <= tout1) {
86                    if(tin2 > 0) {
87                        if(tinx > tiny) {
88                            *x++ = (T)xin;
89                            *y++ = (T)(y1 + FXSYS_Mul(deltay, tinx));
90                        } else {
91                            *x++ = (T)(x1 + FXSYS_Mul(deltax, tiny));
92                            *y++ = (T)yin;
93                        }
94                        ++np;
95                    }
96                    if(tout1 < 1.0f) {
97                        if(toutx < touty) {
98                            *x++ = (T)xout;
99                            *y++ = (T)(y1 + FXSYS_Mul(deltay, toutx));
100                        } else {
101                            *x++ = (T)(x1 + FXSYS_Mul(deltax, touty));
102                            *y++ = (T)yout;
103                        }
104                    } else {
105                        *x++ = x2;
106                        *y++ = y2;
107                    }
108                    ++np;
109                } else {
110                    if(tinx > tiny) {
111                        *x++ = (T)xin;
112                        *y++ = (T)yout;
113                    } else {
114                        *x++ = (T)xout;
115                        *y++ = (T)yin;
116                    }
117                    ++np;
118                }
119            }
120        }
121    }
122    return np;
123}
124}
125#endif
126