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
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
//----------------------------------------------------------------------------
// 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
//----------------------------------------------------------------------------
//
// Perspective 2D transformations
//
//----------------------------------------------------------------------------
#ifndef AGG_TRANS_PERSPECTIVE_INCLUDED
#define AGG_TRANS_PERSPECTIVE_INCLUDED
#include "agg_basics.h"
#include "agg_simul_eq.h"
namespace agg
{
//=======================================================trans_perspective
class trans_perspective
{
public:
//--------------------------------------------------------------------
trans_perspective() : m_valid(false) {}
//--------------------------------------------------------------------
// Arbitrary quadrangle transformations
trans_perspective(const double* src, const double* dst)
{
quad_to_quad(src, dst);
}
//--------------------------------------------------------------------
// Direct transformations
trans_perspective(double x1, double y1, double x2, double y2,
const double* quad)
{
rect_to_quad(x1, y1, x2, y2, quad);
}
//--------------------------------------------------------------------
// Reverse transformations
trans_perspective(const double* quad,
double x1, double y1, double x2, double y2)
{
quad_to_rect(quad, x1, y1, x2, y2);
}
//--------------------------------------------------------------------
// Set the transformations using two arbitrary quadrangles.
void quad_to_quad(const double* src, const double* dst)
{
double left[8][8];
double right[8][1];
unsigned i;
for (i = 0; i < 4; i++)
{
unsigned ix = i * 2;
unsigned iy = ix + 1;
left[ix][0] = 1.0;
left[ix][1] = src[ix];
left[ix][2] = src[iy];
left[ix][3] = 0.0;
left[ix][4] = 0.0;
left[ix][5] = 0.0;
left[ix][6] = -src[ix] * dst[ix];
left[ix][7] = -src[iy] * dst[ix];
right[ix][0] = dst[ix];
left[iy][0] = 0.0;
left[iy][1] = 0.0;
left[iy][2] = 0.0;
left[iy][3] = 1.0;
left[iy][4] = src[ix];
left[iy][5] = src[iy];
left[iy][6] = -src[ix] * dst[iy];
left[iy][7] = -src[iy] * dst[iy];
right[iy][0] = dst[iy];
}
m_valid = simul_eq<8, 1>::solve(left, right, m_mtx);
}
//--------------------------------------------------------------------
// Set the direct transformations, i.e., rectangle -> quadrangle
void rect_to_quad(double x1, double y1, double x2, double y2,
const double* quad)
{
double src[8];
src[0] = src[6] = x1;
src[2] = src[4] = x2;
src[1] = src[3] = y1;
src[5] = src[7] = y2;
quad_to_quad(src, quad);
}
//--------------------------------------------------------------------
// Set the reverse transformations, i.e., quadrangle -> rectangle
void quad_to_rect(const double* quad,
double x1, double y1, double x2, double y2)
{
double dst[8];
dst[0] = dst[6] = x1;
dst[2] = dst[4] = x2;
dst[1] = dst[3] = y1;
dst[5] = dst[7] = y2;
quad_to_quad(quad, dst);
}
//--------------------------------------------------------------------
// Check if the equations were solved successfully
bool is_valid() const { return m_valid; }
//--------------------------------------------------------------------
// Transform a point (x, y)
void transform(double* x, double* y) const
{
double tx = *x;
double ty = *y;
double d = 1.0 / (m_mtx[6][0] * tx + m_mtx[7][0] * ty + 1.0);
*x = (m_mtx[0][0] + m_mtx[1][0] * tx + m_mtx[2][0] * ty) * d;
*y = (m_mtx[3][0] + m_mtx[4][0] * tx + m_mtx[5][0] * ty) * d;
}
//--------------------------------------------------------------------
class iterator_x
{
double den;
double den_step;
double nom_x;
double nom_x_step;
double nom_y;
double nom_y_step;
public:
double x;
double y;
iterator_x() {}
iterator_x(double tx, double ty, double step, const double m[8][1]) :
den(m[6][0] * tx + m[7][0] * ty + 1.0),
den_step(m[6][0] * step),
nom_x(m[0][0] + m[1][0] * tx + m[2][0] * ty),
nom_x_step(m[1][0] * step),
nom_y(m[3][0] + m[4][0] * tx + m[5][0] * ty),
nom_y_step(m[4][0] * step),
x(nom_x / den),
y(nom_y / den)
{
}
void operator ++ ()
{
den += den_step;
nom_x += nom_x_step;
nom_y += nom_y_step;
double d = 1.0 / den;
x = nom_x * d;
y = nom_y * d;
}
};
//--------------------------------------------------------------------
iterator_x begin(double x, double y, double step) const
{
return iterator_x(x, y, step, m_mtx);
}
private:
double m_mtx[8][1];
bool m_valid;
};
}
#endif
|
