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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
|
/*
* Test mipmap generation and lod bias.
*
* Brian Paul
* 17 March 2008
*/
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <GL/glew.h>
#include <GL/glut.h>
#include <GL/glext.h>
#include "readtex.h"
#define TEXTURE_FILE "../images/arch.rgb"
static int TexWidth = 256, TexHeight = 256;
static int WinWidth = 1044, WinHeight = 900;
static GLfloat Bias = 0.0;
static GLboolean ScaleQuads = GL_FALSE;
static GLint Win = 0;
static void
PrintString(const char *s)
{
while (*s) {
glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
s++;
}
}
static void
Display(void)
{
int x, y, bias;
char str[100];
int texWidth = TexWidth, texHeight = TexHeight;
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, WinWidth, 0, WinHeight, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glColor3f(1,1,1);
y = WinHeight - 300;
x = 4;
for (bias = -1; bias < 11; bias++) {
if (ScaleQuads) {
if (bias > 0) {
if (texWidth == 1 && texHeight == 1)
break;
texWidth = TexWidth >> bias;
texHeight = TexHeight >> bias;
if (texWidth < 1)
texWidth = 1;
if (texHeight < 1)
texHeight = 1;
}
glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, 0.0);
}
else {
glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, bias);
}
glRasterPos2f(x, y + TexHeight + 5);
if (ScaleQuads)
sprintf(str, "Texture Level %d: %d x %d",
(bias < 0 ? 0 : bias),
texWidth, texHeight);
else
sprintf(str, "Texture LOD Bias = %d", bias);
PrintString(str);
glPushMatrix();
glTranslatef(x, y, 0);
glEnable(GL_TEXTURE_2D);
glBegin(GL_POLYGON);
glTexCoord2f(0, 0); glVertex2f(0, 0);
glTexCoord2f(1, 0); glVertex2f(texWidth, 0);
glTexCoord2f(1, 1); glVertex2f(texWidth, texHeight);
glTexCoord2f(0, 1); glVertex2f(0, texHeight);
glEnd();
glPopMatrix();
glDisable(GL_TEXTURE_2D);
x += TexWidth + 4;
if (x >= WinWidth) {
x = 4;
y -= 300;
}
}
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
WinWidth = width;
WinHeight = height;
glViewport(0, 0, width, height);
}
static void
Key(unsigned char key, int x, int y)
{
(void) x;
(void) y;
switch (key) {
case 'b':
Bias -= 10;
break;
case 'B':
Bias += 10;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
Bias = 100.0 * (key - '0');
break;
case 's':
ScaleQuads = !ScaleQuads;
break;
case 27:
glutDestroyWindow(Win);
exit(0);
break;
}
glutPostRedisplay();
}
static void
Init(void)
{
GLfloat maxBias;
if (!glutExtensionSupported("GL_EXT_texture_lod_bias")) {
printf("Sorry, GL_EXT_texture_lod_bias not supported by this renderer.\n");
exit(1);
}
if (!glutExtensionSupported("GL_SGIS_generate_mipmap")) {
printf("Sorry, GL_SGIS_generate_mipmap not supported by this renderer.\n");
exit(1);
}
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
if (1) {
/* test auto mipmap generation */
GLint width, height, i;
GLenum format;
GLubyte *image = LoadRGBImage(TEXTURE_FILE, &width, &height, &format);
if (!image) {
printf("Error: could not load texture image %s\n", TEXTURE_FILE);
exit(1);
}
/* resize to TexWidth x TexHeight */
if (width != TexWidth || height != TexHeight) {
GLubyte *newImage = malloc(TexWidth * TexHeight * 4);
gluScaleImage(format, width, height, GL_UNSIGNED_BYTE, image,
TexWidth, TexHeight, GL_UNSIGNED_BYTE, newImage);
free(image);
image = newImage;
}
printf("Using GL_SGIS_generate_mipmap\n");
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
glTexImage2D(GL_TEXTURE_2D, 0, format, TexWidth, TexHeight, 0,
format, GL_UNSIGNED_BYTE, image);
free(image);
/* make sure mipmap was really generated correctly */
width = TexWidth;
height = TexHeight;
for (i = 0; i < 9; i++) {
GLint w, h;
glGetTexLevelParameteriv(GL_TEXTURE_2D, i, GL_TEXTURE_WIDTH, &w);
glGetTexLevelParameteriv(GL_TEXTURE_2D, i, GL_TEXTURE_HEIGHT, &h);
printf("Level %d size: %d x %d\n", i, w, h);
assert(w == width);
assert(h == height);
width /= 2;
height /= 2;
}
}
else {
if (LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) {
printf("Using gluBuildMipmaps()\n");
}
else {
printf("Error: could not load texture image %s\n", TEXTURE_FILE);
exit(1);
}
}
/* mipmapping required for this extension */
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glGetFloatv(GL_MAX_TEXTURE_LOD_BIAS_EXT, &maxBias);
printf("GL_RENDERER: %s\n", (char*) glGetString(GL_RENDERER));
printf("LOD bias range: [%g, %g]\n", -maxBias, maxBias);
printf("Press 's' to toggle quad scaling\n");
}
int
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(WinWidth, WinHeight);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
Win = glutCreateWindow(argv[0]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Display);
Init();
glutMainLoop();
return 0;
}
|
