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"
23 namespace agg
24 {
25 template<class T>
clipping_flags(T x,T y,const rect_base<T> & clip_box)26 inline 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 }
33 template<class T>
clip_liang_barsky(T x1,T y1,T x2,T y2,const rect_base<T> & clip_box,T * x,T * y)34 inline 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