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
|
#include <toys/toy-framework-2.h>
#include <vector>
using std::vector;
using namespace Geom;
using namespace std;
class Box3d: public Toy {
Point orig;
double tmat[3][4];
double c[8][4];
Point corners[8];
PointHandle origin_handle;
PointSetHandle vanishing_points_handles, axes_handles;
void draw(cairo_t *cr, std::ostringstream *notify, int width, int height, bool save, std::ostringstream *timer_stream) override {
Geom::Point dir(1,-2);
cairo_set_source_rgba (cr, 0., 0.125, 0, 1);
// draw vertical lines for the VP sliders and keep the sliders at their horizontal positions
draw_slider_lines (cr);
axes_handles.pts[0][0] = 30;
axes_handles.pts[1][0] = 45;
axes_handles.pts[2][0] = 60;
/* create the transformation matrix for the map P^3 --> P^2 that has the following effect:
(1 : 0 : 0 : 0) --> vanishing point in x direction (= handle #0)
(0 : 1 : 0 : 0) --> vanishing point in y direction (= handle #1)
(0 : 0 : 1 : 0) --> vanishing point in z direction (= handle #2)
(0 : 0 : 0 : 1) --> origin (= handle #3)
*/
for (int j = 0; j < 4; ++j) {
tmat[0][j] = vanishing_points_handles.pts[j][0];
tmat[1][j] = vanishing_points_handles.pts[j][1];
tmat[2][j] = 1;
}
*notify << "Projection matrix:" << endl;
for (auto & i : tmat) {
for (double j : i) {
*notify << j << " ";
}
*notify << endl;
}
// draw the projective images of the box's corners
for (int i = 0; i < 8; ++i) {
corners[i] = proj_image (cr, c[i]);
}
draw_box(cr, corners);
cairo_set_line_width (cr, 2);
cairo_stroke(cr);
Toy::draw(cr, notify, width, height, save,timer_stream);
}
void first_time(int /*argc*/, char** /*argv*/) override {
// Finite images of the three vanishing points and the origin
handles.push_back(&origin_handle);
handles.push_back(&vanishing_points_handles);
handles.push_back(&axes_handles);
vanishing_points_handles.push_back(550,350);
vanishing_points_handles.push_back(150,300);
vanishing_points_handles.push_back(380,40);
vanishing_points_handles.push_back(340,450);
// plane origin
origin_handle.pos = Point(180,65);
// Handles for moving in axes directions
axes_handles.push_back(30,300);
axes_handles.push_back(45,300);
axes_handles.push_back(60,300);
// Box corners
for (int i = 0; i < 8; ++i) {
c[i][0] = ((i & 1) ? 1 : 0);
c[i][1] = ((i & 2) ? 1 : 0);
c[i][2] = ((i & 4) ? 1 : 0);
c[i][3] = 1;
}
orig = origin_handle.pos;
}
Geom::Point proj_image (cairo_t *cr, const double pt[4]) {
double res[3];
for (int j = 0; j < 3; ++j) {
res[j] =
tmat[j][0] * (pt[0] - (axes_handles.pts[0][1]-300)/100)
+ tmat[j][1] * (pt[1] - (axes_handles.pts[1][1]-300)/100)
+ tmat[j][2] * (pt[2] - (axes_handles.pts[2][1]-300)/100)
+ tmat[j][3] * pt[3];
}
if (fabs (res[2]) > 0.000001) {
Geom::Point result = Geom::Point (res[0]/res[2], res[1]/res[2]);
draw_handle(cr, result);
return result;
}
assert(0); // unclipped point
return Geom::Point(0,0);
}
void draw_box (cairo_t *cr, Geom::Point corners[8]) {
cairo_move_to(cr,corners[0]);
cairo_line_to(cr,corners[1]);
cairo_line_to(cr,corners[3]);
cairo_line_to(cr,corners[2]);
cairo_close_path(cr);
cairo_move_to(cr,corners[4]);
cairo_line_to(cr,corners[5]);
cairo_line_to(cr,corners[7]);
cairo_line_to(cr,corners[6]);
cairo_close_path(cr);
for(int i = 0 ; i < 4; i++) {
cairo_move_to(cr,corners[i]);
cairo_line_to(cr,corners[i+4]);
}
}
void draw_slider_lines (cairo_t *cr) {
cairo_move_to(cr, Geom::Point(20,300));
cairo_line_to(cr, Geom::Point(70,300));
for(int i = 0; i < 3; i++) {
cairo_move_to(cr, Geom::Point(30 + 15*i,00));
cairo_line_to(cr, Geom::Point(30 + 15*i,450));
}
cairo_set_line_width (cr, 1);
cairo_set_source_rgba (cr, 0.2, 0.2, 0.2, 1);
cairo_stroke(cr);
}
};
int main(int argc, char **argv) {
init(argc, argv, new Box3d);
return 0;
}
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
|
