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
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#include "texture.h"
static char defaultFile[] = "data/mandrill256.rgb";
GLuint *img;
GLsizei w, h;
GLint comp;
GLfloat kernScale;
/* a few filters... */
GLfloat horizontalEdge3x3[] = {
-1, -1, -1,
2, 2, 2,
-1, -1, -1,
};
GLfloat verticalEdge3x3[] = {
-1, 2, -1,
-1, 2, -1,
-1, 2, -1,
};
GLfloat allEdge3x3[] = {
-2, 1, -2,
1, 4, 1,
-2, 1, -2,
};
GLfloat smooth3x3[] = {
1, 2, 1,
2, 4, 2,
1, 2, 1,
};
GLfloat highpass3x3[] = {
-1, -1, -1,
-1, 9, -1,
-1, -1, -1,
};
GLfloat laplacian5x5[] = {
1, 1, 1, 1, 1,
1, 1, 1, 1, 1,
1, 1, 24, 1, 1,
1, 1, 1, 1, 1,
1, 1, 1, 1, 1,
};
GLfloat box3x3[] = {
1, 1, 1,
1, 1, 1,
1, 1, 1,
};
GLfloat box5x5[] = {
1, 1, 1, 1, 1,
1, 1, 1, 1, 1,
1, 1, 1, 1, 1,
1, 1, 1, 1, 1,
1, 1, 1, 1, 1,
};
struct Kernel {
const char *name;
GLfloat *kern;
GLsizei w, h;
} filters[] = {
{"horizontal edge detect", horizontalEdge3x3, 3, 3},
{"vertical edge detect", verticalEdge3x3, 3, 3},
{"all edge detect", allEdge3x3, 3, 3},
{"3x3 smooth", smooth3x3, 3, 3},
{"3x3 highpass", highpass3x3, 3, 3},
{"5x5 laplacian", laplacian5x5, 5, 5},
{"3x3 box", box3x3, 3, 3},
{"5x5 box", box5x5, 5, 5},
};
struct Kernel *kern;
void kern_normalize(void)
{
GLfloat total, scale, *k;
int i;
k = kern->kern;
total = 0;
for (i = 0; i < kern->w*kern->h; i++) {
total += *k++;
}
if (!total) {
/* kernel sums to 0... */
return;
} else {
scale = 1. / total;
k = kern->kern;
for (i = 0; i < kern->w * kern->h; i++) {
*k *= scale;
k++;
}
}
}
GLfloat acc_kern_scale(void)
{
GLfloat minPossible = 0, maxPossible = 1;
GLfloat *k;
int i;
k = kern->kern;
for (i = 0; i < kern->w*kern->h; i++) {
if (*k < 0) {
minPossible += *k;
} else {
maxPossible += *k;
}
k++;
}
return(1. / ((-minPossible > maxPossible) ? -minPossible : maxPossible));
}
void init(void)
{
kern = &filters[4];
kern_normalize();
kernScale = acc_kern_scale();
}
void load_img(const char *fname)
{
img = read_texture(fname, &w, &h, &comp);
if (!img) {
fprintf(stderr, "Could not open %s\n", fname);
exit(1);
}
}
void reshape(GLsizei winW, GLsizei winH)
{
glViewport(0, 0, w, h);
glLoadIdentity();
glOrtho(0, winW, 0, winH, 0, 5);
}
void acc_convolve(void)
{
int x, y;
for (y = 0; y < kern->h; y++) {
for (x = 0; x < kern->w; x++) {
glRasterPos2i(0, 0);
glBitmap(0, 0, 0, 0, -x, -y, 0);
glDrawPixels(w, h, GL_RGBA, GL_UNSIGNED_BYTE, img);
glAccum(GL_ACCUM, kern->kern[y*kern->w + x]*kernScale);
}
}
glAccum(GL_RETURN, 1./kernScale);
}
void draw(void)
{
GLenum err;
glutSetCursor(GLUT_CURSOR_WAIT);
glClear(GL_COLOR_BUFFER_BIT | GL_ACCUM_BUFFER_BIT);
acc_convolve();
err = glGetError();
if (err != GL_NO_ERROR) printf("Error: %s\n", gluErrorString(err));
glutSetCursor(GLUT_CURSOR_INHERIT);
}
/* ARGSUSED1 */
void key(unsigned char key, int x, int y)
{
if (key == 27) exit(0);
}
void menu(int val)
{
kern = &filters[val];
kern_normalize();
kernScale= acc_kern_scale();
draw();
}
main(int argc, char *argv[])
{
int i;
glutInit(&argc, argv);
if (argc > 1) {
load_img(argv[1]);
} else {
load_img(defaultFile);
}
glutInitWindowSize(w, h);
glutInitWindowPosition(0, 0);
glutInitDisplayMode(GLUT_RGB | GLUT_ACCUM);
glutCreateWindow(argv[0]);
glutDisplayFunc(draw);
glutKeyboardFunc(key);
glutReshapeFunc(reshape);
glutCreateMenu(menu);
for (i = 0; i < sizeof(filters) / sizeof(filters[0]); i++) {
glutAddMenuEntry(filters[i].name, i);
}
glutAttachMenu(GLUT_RIGHT_BUTTON);
init();
glutMainLoop();
return 0;
}
|
