【原创】OPGL ES加载PNG图片为纹理
因为BMP图片在显示的时候周边有比较难看的锯齿图，OPGL ES基本上都是使用对BMP加载纹理图的做法，很少加载PNG纹理图，今天在某国外网站看到这么一段使用OPGL加载PNG纹理图代码，摘录下来。
论坛上有人试验成功，但是我使用libpng库的时候，用png_read_info 读取png图片信息时出错，正在调试中。大家讨论讨论。
通过该链接可以下载库和源码http://www.tenik.co.jp/~adachi/wince/zlibce/index.html
源码如下：
1 /*
2 * png.c -- png texture loader
3 * last modification: aug. 14, 2007
4 *
5 * Copyright (c) 2005-2007 David HENRY
6 *
7 * Permission is hereby granted, free of charge, to any person
8 * obtaining a copy of this software and associated documentation
9 * files (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use,
11 * copy, modify, merge, publish, distribute, sublicense, and/or
12 * sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be
16 * included in all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21 * NONINFRINGEMENT.
22 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
23 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
24 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
25 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
26 *
27 * gcc -Wall -ansi -lGL -lGLU -lglut
28 * `libpng12-config --cflags --libs` png.c -o png
29 */
30
31 #include <GL/glut.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35
36 #include <png.h>
37
38 /* Microsoft Visual C++ */
39 #ifdef _MSC_VER
40 #pragma comment (lib, "libpng.lib")
41 #pragma comment (lib, "zlib.lib")
42 #pragma comment (linker, "/nodefaultlib:libc")
43 #endif /* _MSC_VER */
44
45 /* OpenGL texture info */
46 struct gl_texture_t
47 {
48 GLsizei width;
49 GLsizei height;
50
51 GLenum format;
52 GLint internalFormat;
53 GLuint id;
54
55 GLubyte *texels;
56 };
57
58 /* Texture id for the demo */
59 GLuint texId;
60
61
62 static void
63 GetPNGtextureInfo (int color_type, struct gl_texture_t *texinfo)
64 {
65 switch (color_type)
66 {
67 case PNG_COLOR_TYPE_GRAY:
68 texinfo->format = GL_LUMINANCE;
69 texinfo->internalFormat = 1;
70 break;
71
72 case PNG_COLOR_TYPE_GRAY_ALPHA:
73 texinfo->format = GL_LUMINANCE_ALPHA;
74 texinfo->internalFormat = 2;
75 break;
76
77 case PNG_COLOR_TYPE_RGB:
78 texinfo->format = GL_RGB;
79 texinfo->internalFormat = 3;
80 break;
81
82 case PNG_COLOR_TYPE_RGB_ALPHA:
83 texinfo->format = GL_RGBA;
84 texinfo->internalFormat = 4;
85 break;
86
87 default:
88 /* Badness */
89 break;
90 }
91 }
92
93 static struct gl_texture_t *
94 ReadPNGFromFile (const char *filename)
95 {
96 struct gl_texture_t *texinfo;
97 png_byte magic[8];
98 png_structp png_ptr;
99 png_infop info_ptr;
100 int bit_depth, color_type;
101 FILE *fp = NULL;
102 png_bytep *row_pointers = NULL;
103 png_uint_32 w, h;
104 int i;
105
106 /* Open image file */
107 fp = fopen (filename, "rb");
108 if (!fp)
109 {
110 fprintf (stderr, "error: couldn't open \"%s\"!\n", filename);
111 return NULL;
112 }
113
114 /* Read magic number */
115 fread (magic, 1, sizeof (magic), fp);
116
117 /* Check for valid magic number */
118 if (!png_check_sig (magic, sizeof (magic)))
119 {
120 fprintf (stderr, "error: \"%s\" is not a valid PNG image!\n",
121 filename);
122 fclose (fp);
123 return NULL;
124 }
125
126 /* Create a png read struct */
127 png_ptr = png_create_read_struct
128 (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
129 if (!png_ptr)
130 {
131 fclose (fp);
132 return NULL;
133 }
134
135 /* Create a png info struct */
136 info_ptr = png_create_info_struct (png_ptr);
137 if (!info_ptr)
138 {
139 fclose (fp);
140 png_destroy_read_struct (&png_ptr, NULL, NULL);
141 return NULL;
142 }
143
144 /* Create our OpenGL texture object */
145 texinfo = (struct gl_texture_t *)
146 malloc (sizeof (struct gl_texture_t));
147
148 /* Initialize the setjmp for returning properly after a libpng
149 error occured */
150 if (setjmp (png_jmpbuf (png_ptr)))
151 {
152 fclose (fp);
153 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
154
155 if (row_pointers)
156 free (row_pointers);
157
158 if (texinfo)
159 {
160 if (texinfo->texels)
161 free (texinfo->texels);
162
163 free (texinfo);
164 }
165
166 return NULL;
167 }
168
169 /* Setup libpng for using standard C fread() function
170 with our FILE pointer */
171 png_init_io (png_ptr, fp);
172
173 /* Tell libpng that we have already read the magic number */
174 png_set_sig_bytes (png_ptr, sizeof (magic));
175
176 /* Read png info */
177 png_read_info (png_ptr, info_ptr);
178
179 /* Get some usefull information from header */
180 bit_depth = png_get_bit_depth (png_ptr, info_ptr);
181 color_type = png_get_color_type (png_ptr, info_ptr);
182
183 /* Convert index color images to RGB images */
184 if (color_type == PNG_COLOR_TYPE_PALETTE)
185 png_set_palette_to_rgb (png_ptr);
186
187 /* Convert 1-2-4 bits grayscale images to 8 bits
188 grayscale. */
189 if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
190 png_set_gray_1_2_4_to_8 (png_ptr);
191
192 if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
193 png_set_tRNS_to_alpha (png_ptr);
194
195 if (bit_depth == 16)
196 png_set_strip_16 (png_ptr);
197 else if (bit_depth < 8)
198 png_set_packing (png_ptr);
199
200 /* Update info structure to apply transformations */
201 png_read_update_info (png_ptr, info_ptr);
202
203 /* Retrieve updated information */
204 png_get_IHDR (png_ptr, info_ptr, &w, &h, &bit_depth,
205 &color_type, NULL, NULL, NULL);
206 texinfo->width = w;
207 texinfo->height = h;
208
209 /* Get image format and components per pixel */
210 GetPNGtextureInfo (color_type, texinfo);
211
212 /* We can now allocate memory for storing pixel data */
213 texinfo->texels = (GLubyte *)malloc (sizeof (GLubyte) * texinfo->width
214 * texinfo->height * texinfo->internalFormat);
215
216 /* Setup a pointer array. Each one points at the begening of a row. */
217 row_pointers = (png_bytep *)malloc (sizeof (png_bytep) * texinfo->height);
218
219 for (i = 0; i < texinfo->height; ++i)
220 {
221 row_pointers[i] = (png_bytep)(texinfo->texels +
222 ((texinfo->height - (i + 1)) * texinfo->width * texinfo->internalFormat));
223 }
224
225 /* Read pixel data using row pointers */
226 png_read_image (png_ptr, row_pointers);
227
228 /* Finish decompression and release memory */
229 png_read_end (png_ptr, NULL);
230 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
231
232 /* We don't need row pointers anymore */
233 free (row_pointers);
234
235 fclose (fp);
236 return texinfo;
237 }
238
239 GLuint
240 loadPNGTexture (const char *filename)
241 {
242 struct gl_texture_t *png_tex = NULL;
243 GLuint tex_id = 0;
244
245 png_tex = ReadPNGFromFile (filename);
246
247 if (png_tex && png_tex->texels)
248 {
249 /* Generate texture */
250 glGenTextures (1, &png_tex->id);
251 glBindTexture (GL_TEXTURE_2D, png_tex->id);
252
253 /* Setup some parameters for texture filters and mipmapping */
254 glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
255 glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
256
257 #if 0
258 glTexImage2D (GL_TEXTURE_2D, 0, png_tex->internalFormat,
259 png_tex->width, png_tex->height, 0, png_tex->format,
260 GL_UNSIGNED_BYTE, png_tex->texels);
261 #else
262 gluBuild2DMipmaps (GL_TEXTURE_2D, png_tex->internalFormat,
263 png_tex->width, png_tex->height,
264 png_tex->format, GL_UNSIGNED_BYTE, png_tex->texels);
265 #endif
266
267 tex_id = png_tex->id;
268
269 /* OpenGL has its own copy of texture data */
270 free (png_tex->texels);
271 free (png_tex);
272 }
273
274 return tex_id;
275 }
276
277 static void
278 cleanup ()
279 {
280 glDeleteTextures (1, &texId);
281 }
282
283 static void
284 init (const char *filename)
285 {
286 /* Initialize OpenGL */
287 glClearColor (1, 0.8f, 0.8f,0.0f);
288 glShadeModel (GL_SMOOTH);
289
290 glEnable (GL_DEPTH_TEST);
291
292 glEnable (GL_BLEND);
293 glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
294
295 /* Load PNG texture from file */
296 texId = loadPNGTexture (filename);
297 if (!texId)
298 exit (EXIT_FAILURE);
299 }
300
301 static void
302 reshape (int w, int h)
303 {
304 if (h == 0)
305 h = 1;
306 glViewport (0, 0, (GLsizei)w, (GLsizei)h);
307
308 glMatrixMode (GL_PROJECTION);
309 glLoadIdentity ();
310 gluPerspective (45.0, w/(GLdouble)h, 0.1, 1000.0);
311
312 glMatrixMode (GL_MODELVIEW);
313 glLoadIdentity ();
314
315 glutPostRedisplay ();
316 }
317
318 static void
319 display ()
320 {
321 glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
322 glLoadIdentity ();
323
324 glEnable (GL_TEXTURE_2D);
325 glBindTexture (GL_TEXTURE_2D, texId);
326
327 /* Draw textured quad */
328 glTranslatef (0.0, 0.0, -5.0);
329 glBegin (GL_QUADS);
330 glTexCoord2f (0.0f, 0.0f);
331 glVertex3f (-1.0f, -1.0f, 0.0f);
332
333 glTexCoord2f (1.0f, 0.0f);
334 glVertex3f (1.0f, -1.0f, 0.0f);
335
336 glTexCoord2f (1.0f, 1.0f);
337 glVertex3f (1.0f, 1.0f, 0.0f);
338
339 glTexCoord2f (0.0f, 1.0f);
340 glVertex3f (-1.0f, 1.0f, 0.0f);
341
342 glTexCoord2f(0,0);
343 glVertex3f(0,-1,-1);
344
345 glTexCoord2f(1,0);
346 glVertex3f(0,1,-1);
347
348 glTexCoord2f(1,1);
349 glVertex3f(0,1,1);
350
351 glTexCoord2f(0,1);
352 glVertex3f(0,-1,1);
353 glEnd ();
354
355 glDisable (GL_TEXTURE_2D);
356
357 glutSwapBuffers ();
358 }
359
360 static void
361 keyboard (unsigned char key, int x, int y)
362 {
363 /* Escape */
364 if (key == 27)
365 exit (0);
366 }
367
368 int
369 main (int argc, char *argv[])
370 {
371 if (argc < 2)
372 {
373 fprintf (stderr, "usage: %s <filename.png>\n", argv[0]);
374 return -1;
375 }
376
377 glutInit (&argc, argv);
378 glutInitDisplayMode (GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
379 glutInitWindowSize (640, 480);
380 glutCreateWindow ("PNG Texture Demo");
381
382 atexit (cleanup);
383 init (argv[1]);
384
385 glutReshapeFunc (reshape);
386 glutDisplayFunc (display);
387 glutKeyboardFunc (keyboard);
388
389 glutMainLoop ();
390
391 return 0;
392 }
2 * png.c -- png texture loader
3 * last modification: aug. 14, 2007
4 *
5 * Copyright (c) 2005-2007 David HENRY
6 *
7 * Permission is hereby granted, free of charge, to any person
8 * obtaining a copy of this software and associated documentation
9 * files (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use,
11 * copy, modify, merge, publish, distribute, sublicense, and/or
12 * sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be
16 * included in all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21 * NONINFRINGEMENT.
22 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
23 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
24 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
25 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
26 *
27 * gcc -Wall -ansi -lGL -lGLU -lglut
28 * `libpng12-config --cflags --libs` png.c -o png
29 */
30
31 #include <GL/glut.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35
36 #include <png.h>
37
38 /* Microsoft Visual C++ */
39 #ifdef _MSC_VER
40 #pragma comment (lib, "libpng.lib")
41 #pragma comment (lib, "zlib.lib")
42 #pragma comment (linker, "/nodefaultlib:libc")
43 #endif /* _MSC_VER */
44
45 /* OpenGL texture info */
46 struct gl_texture_t
47 {
48 GLsizei width;
49 GLsizei height;
50
51 GLenum format;
52 GLint internalFormat;
53 GLuint id;
54
55 GLubyte *texels;
56 };
57
58 /* Texture id for the demo */
59 GLuint texId;
60
61
62 static void
63 GetPNGtextureInfo (int color_type, struct gl_texture_t *texinfo)
64 {
65 switch (color_type)
66 {
67 case PNG_COLOR_TYPE_GRAY:
68 texinfo->format = GL_LUMINANCE;
69 texinfo->internalFormat = 1;
70 break;
71
72 case PNG_COLOR_TYPE_GRAY_ALPHA:
73 texinfo->format = GL_LUMINANCE_ALPHA;
74 texinfo->internalFormat = 2;
75 break;
76
77 case PNG_COLOR_TYPE_RGB:
78 texinfo->format = GL_RGB;
79 texinfo->internalFormat = 3;
80 break;
81
82 case PNG_COLOR_TYPE_RGB_ALPHA:
83 texinfo->format = GL_RGBA;
84 texinfo->internalFormat = 4;
85 break;
86
87 default:
88 /* Badness */
89 break;
90 }
91 }
92
93 static struct gl_texture_t *
94 ReadPNGFromFile (const char *filename)
95 {
96 struct gl_texture_t *texinfo;
97 png_byte magic[8];
98 png_structp png_ptr;
99 png_infop info_ptr;
100 int bit_depth, color_type;
101 FILE *fp = NULL;
102 png_bytep *row_pointers = NULL;
103 png_uint_32 w, h;
104 int i;
105
106 /* Open image file */
107 fp = fopen (filename, "rb");
108 if (!fp)
109 {
110 fprintf (stderr, "error: couldn't open \"%s\"!\n", filename);
111 return NULL;
112 }
113
114 /* Read magic number */
115 fread (magic, 1, sizeof (magic), fp);
116
117 /* Check for valid magic number */
118 if (!png_check_sig (magic, sizeof (magic)))
119 {
120 fprintf (stderr, "error: \"%s\" is not a valid PNG image!\n",
121 filename);
122 fclose (fp);
123 return NULL;
124 }
125
126 /* Create a png read struct */
127 png_ptr = png_create_read_struct
128 (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
129 if (!png_ptr)
130 {
131 fclose (fp);
132 return NULL;
133 }
134
135 /* Create a png info struct */
136 info_ptr = png_create_info_struct (png_ptr);
137 if (!info_ptr)
138 {
139 fclose (fp);
140 png_destroy_read_struct (&png_ptr, NULL, NULL);
141 return NULL;
142 }
143
144 /* Create our OpenGL texture object */
145 texinfo = (struct gl_texture_t *)
146 malloc (sizeof (struct gl_texture_t));
147
148 /* Initialize the setjmp for returning properly after a libpng
149 error occured */
150 if (setjmp (png_jmpbuf (png_ptr)))
151 {
152 fclose (fp);
153 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
154
155 if (row_pointers)
156 free (row_pointers);
157
158 if (texinfo)
159 {
160 if (texinfo->texels)
161 free (texinfo->texels);
162
163 free (texinfo);
164 }
165
166 return NULL;
167 }
168
169 /* Setup libpng for using standard C fread() function
170 with our FILE pointer */
171 png_init_io (png_ptr, fp);
172
173 /* Tell libpng that we have already read the magic number */
174 png_set_sig_bytes (png_ptr, sizeof (magic));
175
176 /* Read png info */
177 png_read_info (png_ptr, info_ptr);
178
179 /* Get some usefull information from header */
180 bit_depth = png_get_bit_depth (png_ptr, info_ptr);
181 color_type = png_get_color_type (png_ptr, info_ptr);
182
183 /* Convert index color images to RGB images */
184 if (color_type == PNG_COLOR_TYPE_PALETTE)
185 png_set_palette_to_rgb (png_ptr);
186
187 /* Convert 1-2-4 bits grayscale images to 8 bits
188 grayscale. */
189 if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
190 png_set_gray_1_2_4_to_8 (png_ptr);
191
192 if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
193 png_set_tRNS_to_alpha (png_ptr);
194
195 if (bit_depth == 16)
196 png_set_strip_16 (png_ptr);
197 else if (bit_depth < 8)
198 png_set_packing (png_ptr);
199
200 /* Update info structure to apply transformations */
201 png_read_update_info (png_ptr, info_ptr);
202
203 /* Retrieve updated information */
204 png_get_IHDR (png_ptr, info_ptr, &w, &h, &bit_depth,
205 &color_type, NULL, NULL, NULL);
206 texinfo->width = w;
207 texinfo->height = h;
208
209 /* Get image format and components per pixel */
210 GetPNGtextureInfo (color_type, texinfo);
211
212 /* We can now allocate memory for storing pixel data */
213 texinfo->texels = (GLubyte *)malloc (sizeof (GLubyte) * texinfo->width
214 * texinfo->height * texinfo->internalFormat);
215
216 /* Setup a pointer array. Each one points at the begening of a row. */
217 row_pointers = (png_bytep *)malloc (sizeof (png_bytep) * texinfo->height);
218
219 for (i = 0; i < texinfo->height; ++i)
220 {
221 row_pointers[i] = (png_bytep)(texinfo->texels +
222 ((texinfo->height - (i + 1)) * texinfo->width * texinfo->internalFormat));
223 }
224
225 /* Read pixel data using row pointers */
226 png_read_image (png_ptr, row_pointers);
227
228 /* Finish decompression and release memory */
229 png_read_end (png_ptr, NULL);
230 png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
231
232 /* We don't need row pointers anymore */
233 free (row_pointers);
234
235 fclose (fp);
236 return texinfo;
237 }
238
239 GLuint
240 loadPNGTexture (const char *filename)
241 {
242 struct gl_texture_t *png_tex = NULL;
243 GLuint tex_id = 0;
244
245 png_tex = ReadPNGFromFile (filename);
246
247 if (png_tex && png_tex->texels)
248 {
249 /* Generate texture */
250 glGenTextures (1, &png_tex->id);
251 glBindTexture (GL_TEXTURE_2D, png_tex->id);
252
253 /* Setup some parameters for texture filters and mipmapping */
254 glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
255 glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
256
257 #if 0
258 glTexImage2D (GL_TEXTURE_2D, 0, png_tex->internalFormat,
259 png_tex->width, png_tex->height, 0, png_tex->format,
260 GL_UNSIGNED_BYTE, png_tex->texels);
261 #else
262 gluBuild2DMipmaps (GL_TEXTURE_2D, png_tex->internalFormat,
263 png_tex->width, png_tex->height,
264 png_tex->format, GL_UNSIGNED_BYTE, png_tex->texels);
265 #endif
266
267 tex_id = png_tex->id;
268
269 /* OpenGL has its own copy of texture data */
270 free (png_tex->texels);
271 free (png_tex);
272 }
273
274 return tex_id;
275 }
276
277 static void
278 cleanup ()
279 {
280 glDeleteTextures (1, &texId);
281 }
282
283 static void
284 init (const char *filename)
285 {
286 /* Initialize OpenGL */
287 glClearColor (1, 0.8f, 0.8f,0.0f);
288 glShadeModel (GL_SMOOTH);
289
290 glEnable (GL_DEPTH_TEST);
291
292 glEnable (GL_BLEND);
293 glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
294
295 /* Load PNG texture from file */
296 texId = loadPNGTexture (filename);
297 if (!texId)
298 exit (EXIT_FAILURE);
299 }
300
301 static void
302 reshape (int w, int h)
303 {
304 if (h == 0)
305 h = 1;
306 glViewport (0, 0, (GLsizei)w, (GLsizei)h);
307
308 glMatrixMode (GL_PROJECTION);
309 glLoadIdentity ();
310 gluPerspective (45.0, w/(GLdouble)h, 0.1, 1000.0);
311
312 glMatrixMode (GL_MODELVIEW);
313 glLoadIdentity ();
314
315 glutPostRedisplay ();
316 }
317
318 static void
319 display ()
320 {
321 glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
322 glLoadIdentity ();
323
324 glEnable (GL_TEXTURE_2D);
325 glBindTexture (GL_TEXTURE_2D, texId);
326
327 /* Draw textured quad */
328 glTranslatef (0.0, 0.0, -5.0);
329 glBegin (GL_QUADS);
330 glTexCoord2f (0.0f, 0.0f);
331 glVertex3f (-1.0f, -1.0f, 0.0f);
332
333 glTexCoord2f (1.0f, 0.0f);
334 glVertex3f (1.0f, -1.0f, 0.0f);
335
336 glTexCoord2f (1.0f, 1.0f);
337 glVertex3f (1.0f, 1.0f, 0.0f);
338
339 glTexCoord2f (0.0f, 1.0f);
340 glVertex3f (-1.0f, 1.0f, 0.0f);
341
342 glTexCoord2f(0,0);
343 glVertex3f(0,-1,-1);
344
345 glTexCoord2f(1,0);
346 glVertex3f(0,1,-1);
347
348 glTexCoord2f(1,1);
349 glVertex3f(0,1,1);
350
351 glTexCoord2f(0,1);
352 glVertex3f(0,-1,1);
353 glEnd ();
354
355 glDisable (GL_TEXTURE_2D);
356
357 glutSwapBuffers ();
358 }
359
360 static void
361 keyboard (unsigned char key, int x, int y)
362 {
363 /* Escape */
364 if (key == 27)
365 exit (0);
366 }
367
368 int
369 main (int argc, char *argv[])
370 {
371 if (argc < 2)
372 {
373 fprintf (stderr, "usage: %s <filename.png>\n", argv[0]);
374 return -1;
375 }
376
377 glutInit (&argc, argv);
378 glutInitDisplayMode (GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
379 glutInitWindowSize (640, 480);
380 glutCreateWindow ("PNG Texture Demo");
381
382 atexit (cleanup);
383 init (argv[1]);
384
385 glutReshapeFunc (reshape);
386 glutDisplayFunc (display);
387 glutKeyboardFunc (keyboard);
388
389 glutMainLoop ();
390
391 return 0;
392 }
posted on 2009-12-14 19:49 IamEasy_Man 阅读(3329) 评论(6) 收藏 举报
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