src/glpng.c

   1 /*
   2  * PNG loader library for OpenGL v1.45 (10/07/00)
   3  * by Ben Wyatt ben@wyatt100.freeserve.co.uk
   4  * Using LibPNG 1.0.2 and ZLib 1.1.3
   5  *
   6  * This software is provided 'as-is', without any express or implied warranty.
   7  * In no event will the author be held liable for any damages arising from the
   8  * use of this software.
   9  *
  10  * Permission is hereby granted to use, copy, modify, and distribute this
  11  * source code, or portions hereof, for any purpose, without fee, subject to
  12  * the following restrictions:
  13  *
  14  * 1. The origin of this source code must not be misrepresented. You must not
  15  *    claim that you wrote the original software. If you use this software in
  16  *    a product, an acknowledgment in the product documentation would be
  17  *    appreciated but is not required.
  18  * 2. Altered versions must be plainly marked as such and must not be
  19  *    misrepresented as being the original source.
  20  * 3. This notice must not be removed or altered from any source distribution.
  21  */
  22
  23 #ifdef _WIN32 /* Stupid Windows needs to include windows.h before gl.h */
  24         #undef FAR
  25         #include <windows.h>
  26 #endif
  27
  28 #include <GL/glpng.h>
  29 #include <GL/gl.h>
  30 #include <stdlib.h>
  31 #include <math.h>
  32 #include "png/png.h"
  33
  34 /* Used to decide if GL/gl.h supports the paletted extension */
  35 #ifdef GL_COLOR_INDEX1_EXT
  36 #define SUPPORTS_PALETTE_EXT
  37 #endif
  38
  39 static unsigned char DefaultAlphaCallback(unsigned char red, unsigned char green, unsigned char blue) {
  40         return 255;
  41 }
  42
  43 static unsigned char StencilRed = 0, StencilGreen = 0, StencilBlue = 0;
  44 static unsigned char (*AlphaCallback)(unsigned char red, unsigned char green, unsigned char blue) = DefaultAlphaCallback;
  45 static int StandardOrientation = 0;
  46
  47 #ifdef SUPPORTS_PALETTE_EXT
  48 #ifdef _WIN32
  49 static PFNGLCOLORTABLEEXTPROC glColorTableEXT = NULL;
  50 #endif
  51 #endif
  52
  53 static int PalettedTextures = -1;
  54 static GLint MaxTextureSize = 0;
  55
  56 /* screenGamma = displayGamma/viewingGamma
  57  * displayGamma = CRT has gamma of ~2.2
  58  * viewingGamma depends on platform. PC is 1.0, Mac is 1.45, SGI defaults
  59  * to 1.7, but this can be checked and changed w/ /usr/sbin/gamma command.
  60  * If the environment variable VIEWING_GAMMA is set, adjust gamma per this value.
  61  */
  62 #ifdef _MAC
  63         static double screenGamma = 2.2 / 1.45;
  64 #elif SGI
  65         static double screenGamma = 2.2 / 1.7;
  66 #else /* PC/default */
  67         static double screenGamma = 2.2 / 1.0;
  68 #endif
  69
  70 static char gammaExplicit = 0;  /*if  */
  71
  72 static void checkForGammaEnv()
  73 {
  74         double viewingGamma;
  75         char *gammaEnv = getenv("VIEWING_GAMMA");
  76
  77         if(gammaEnv && !gammaExplicit)
  78         {
  79                 sscanf(gammaEnv, "%lf", &viewingGamma);
  80                 screenGamma = 2.2/viewingGamma;
  81         }
  82 }
  83
  84 /* Returns a safe texture size to use (ie a power of 2), based on the current texture size "i" */
  85 static int SafeSize(int i) {
  86         int p;
  87
  88         if (i > MaxTextureSize) return MaxTextureSize;
  89
  90         for (p = 0; p < 24; p++)
  91                 if (i <= (1<<p))
  92                         return 1<<p;
  93
  94         return MaxTextureSize;
  95 }
  96
  97 /* Resize the texture since gluScaleImage doesn't work on everything */
  98 static void Resize(int components, const png_bytep d1, int w1, int h1, png_bytep d2, int w2, int h2) {
  99         const float sx = (float) w1/w2, sy = (float) h1/h2;
 100         int x, y, xx, yy, c;
 101         png_bytep d;
 102
 103         for (y = 0; y < h2; y++) {
 104                 yy = (int) (y*sy)*w1;
 105
 106                 for (x = 0; x < w2; x++) {
 107                         xx = (int) (x*sx);
 108                         d = d1 + (yy+xx)*components;
 109
 110                         for (c = 0; c < components; c++)
 111                                 *d2++ = *d++;
 112                 }
 113         }
 114 }
 115
 116 static int ExtSupported(const char *x) {
 117         static const GLubyte *ext = NULL;
 118         const char *c;
 119         int xlen = strlen(x);
 120
 121         if (ext == NULL) ext = glGetString(GL_EXTENSIONS);
 122
 123         c = (const char*)ext;
 124
 125         while (*c != '\0') {
 126                 if (strcmp(c, x) == 0 && (c[xlen] == '\0' || c[xlen] == ' ')) return 1;
 127                 c++;
 128         }
 129
 130         return 0;
 131 }
 132
 133 #define GET(o) ((int)*(data + (o)))
 134
 135 static int HalfSize(GLint components, GLint width, GLint height, const unsigned char *data, unsigned char *d, int filter) {
 136         int x, y, c;
 137         int line = width*components;
 138
 139         if (width > 1 && height > 1) {
 140                 if (filter)
 141                         for (y = 0; y < height; y += 2) {
 142                                 for (x = 0; x < width; x += 2) {
 143                                         for (c = 0; c < components; c++) {
 144                                                 *d++ = (GET(0)+GET(components)+GET(line)+GET(line+components)) / 4;
 145                                                 data++;
 146                                         }
 147                                         data += components;
 148                                 }
 149                                 data += line;
 150                         }
 151                 else
 152                         for (y = 0; y < height; y += 2) {
 153                                 for (x = 0; x < width; x += 2) {
 154                                         for (c = 0; c < components; c++) {
 155                                                 *d++ = GET(0);
 156                                                 data++;
 157                                         }
 158                                         data += components;
 159                                 }
 160                                 data += line;
 161                         }
 162         }
 163         else if (width > 1 && height == 1) {
 164                 if (filter)
 165                         for (y = 0; y < height; y += 1) {
 166                                 for (x = 0; x < width; x += 2) {
 167                                         for (c = 0; c < components; c++) {
 168                                                 *d++ = (GET(0)+GET(components)) / 2;
 169                                                 data++;
 170                                         }
 171                                         data += components;
 172                                 }
 173                         }
 174                 else
 175                         for (y = 0; y < height; y += 1) {
 176                                 for (x = 0; x < width; x += 2) {
 177                                         for (c = 0; c < components; c++) {
 178                                                 *d++ = GET(0);
 179                                                 data++;
 180                                         }
 181                                         data += components;
 182                                 }
 183                         }
 184         }
 185         else if (width == 1 && height > 1) {
 186                 if (filter)
 187                         for (y = 0; y < height; y += 2) {
 188                                 for (x = 0; x < width; x += 1) {
 189                                         for (c = 0; c < components; c++) {
 190                                                 *d++ = (GET(0)+GET(line)) / 2;
 191                                                 data++;
 192                                         }
 193                                 }
 194                                 data += line;
 195                         }
 196                 else
 197                         for (y = 0; y < height; y += 2) {
 198                                 for (x = 0; x < width; x += 1) {
 199                                         for (c = 0; c < components; c++) {
 200                                                 *d++ = GET(0);
 201                                                 data++;
 202                                         }
 203                                 }
 204                                 data += line;
 205                         }
 206         }
 207         else {
 208                 return 0;
 209         }
 210
 211         return 1;
 212 }
 213
 214 #undef GET
 215
 216 /* Replacement for gluBuild2DMipmaps so GLU isn't needed */
 217 static void Build2DMipmaps(GLint components, GLint width, GLint height, GLenum format, const unsigned char *data, int filter) {
 218         int level = 0;
 219         unsigned char *d = (unsigned char *) malloc((width/2)*(height/2)*components+4);
 220         const unsigned char *last = data;
 221
 222         glTexImage2D(GL_TEXTURE_2D, level, components, width, height, 0, format, GL_UNSIGNED_BYTE, data);
 223         level++;
 224
 225         while (HalfSize(components, width, height, last, d, filter)) {
 226                 if (width  > 1) width  /= 2;
 227                 if (height > 1) height /= 2;
 228
 229                 glTexImage2D(GL_TEXTURE_2D, level, components, width, height, 0, format, GL_UNSIGNED_BYTE, d);
 230                 level++;
 231                 last = d;
 232         }
 233
 234         free(d);
 235 }
 236
 237 int APIENTRY pngLoadRaw(const char *filename, pngRawInfo *pinfo) {
 238         int result;
 239         FILE *fp = fopen(filename, "rb");
 240         if (fp == NULL) return 0;
 241
 242         result = pngLoadRawF(fp, pinfo);
 243
 244         if (fclose(fp) != 0) {
 245                 if (result) {
 246                         free(pinfo->Data);
 247                         free(pinfo->Palette);
 248                 }
 249                 return 0;
 250         }
 251
 252         return result;
 253 }
 254
 255 int APIENTRY pngLoadRawF(FILE *fp, pngRawInfo *pinfo) {
 256         unsigned char header[8];
 257         png_structp png;
 258         png_infop   info;
 259         png_infop   endinfo;
 260         png_bytep   data;
 261    png_bytep  *row_p;
 262    double       fileGamma;
 263
 264         png_uint_32 width, height;
 265         int depth, color;
 266
 267         png_uint_32 i;
 268
 269         if (pinfo == NULL) return 0;
 270
 271         fread(header, 1, 8, fp);
 272         if (!png_check_sig(header, 8)) return 0;
 273
 274         png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 275         info = png_create_info_struct(png);
 276         endinfo = png_create_info_struct(png);
 277
 278         // DH: added following lines
 279         if (setjmp(png->jmpbuf))
 280         {
 281                 png_destroy_read_struct(&png, &info, &endinfo);
 282                 return 0;
 283         }
 284         // ~DH
 285
 286         png_init_io(png, fp);
 287         png_set_sig_bytes(png, 8);
 288         png_read_info(png, info);
 289         png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
 290
 291         pinfo->Width  = width;
 292         pinfo->Height = height;
 293         pinfo->Depth  = depth;
 294
 295         /*--GAMMA--*/
 296         checkForGammaEnv();
 297         if (png_get_gAMA(png, info, &fileGamma))
 298                 png_set_gamma(png, screenGamma, fileGamma);
 299         else
 300                 png_set_gamma(png, screenGamma, 1.0/2.2);
 301
 302         png_read_update_info(png, info);
 303
 304         data = (png_bytep) malloc(png_get_rowbytes(png, info)*height);
 305         row_p = (png_bytep *) malloc(sizeof(png_bytep)*height);
 306
 307         for (i = 0; i < height; i++) {
 308                 if (StandardOrientation)
 309                         row_p[height - 1 - i] = &data[png_get_rowbytes(png, info)*i];
 310                 else
 311                         row_p[i] = &data[png_get_rowbytes(png, info)*i];
 312         }
 313
 314         png_read_image(png, row_p);
 315         free(row_p);
 316
 317         if (color == PNG_COLOR_TYPE_PALETTE) {
 318                 int cols;
 319                 png_get_PLTE(png, info, (png_colorp *) &pinfo->Palette, &cols);
 320         }
 321         else {
 322                 pinfo->Palette = NULL;
 323         }
 324
 325         if (color&PNG_COLOR_MASK_ALPHA) {
 326                 if (color&PNG_COLOR_MASK_PALETTE || color == PNG_COLOR_TYPE_GRAY_ALPHA)
 327                         pinfo->Components = 2;
 328                 else
 329                         pinfo->Components = 4;
 330                 pinfo->Alpha = 8;
 331         }
 332         else {
 333                 if (color&PNG_COLOR_MASK_PALETTE || color == PNG_COLOR_TYPE_GRAY)
 334                         pinfo->Components = 1;
 335                 else
 336                         pinfo->Components = 3;
 337                 pinfo->Alpha = 0;
 338         }
 339
 340         pinfo->Data = data;
 341
 342    png_read_end(png, endinfo);
 343         png_destroy_read_struct(&png, &info, &endinfo);
 344
 345         return 1;
 346 }
 347
 348 int APIENTRY pngLoad(const char *filename, int mipmap, int trans, pngInfo *pinfo) {
 349         int result;
 350         FILE *fp = fopen(filename, "rb");
 351         if (fp == NULL) return 0;
 352
 353         result = pngLoadF(fp, mipmap, trans, pinfo);
 354
 355         if (fclose(fp) != 0) return 0;
 356
 357         return result;
 358 }
 359
 360 int APIENTRY pngLoadF(FILE *fp, int mipmap, int trans, pngInfo *pinfo) {
 361         GLint pack, unpack;
 362         unsigned char header[8];
 363         png_structp png;
 364         png_infop   info;
 365         png_infop   endinfo;
 366         png_bytep   data, data2;
 367    png_bytep  *row_p;
 368    double       fileGamma;
 369
 370         png_uint_32 width, height, rw, rh;
 371         int depth, color;
 372
 373         png_uint_32 i;
 374
 375         fread(header, 1, 8, fp);
 376         if (!png_check_sig(header, 8)) return 0;
 377
 378         png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 379         info = png_create_info_struct(png);
 380         endinfo = png_create_info_struct(png);
 381
 382         // DH: added following lines
 383         if (setjmp(png->jmpbuf))
 384         {
 385                 png_destroy_read_struct(&png, &info, &endinfo);
 386                 return 0;
 387         }
 388         // ~DH
 389
 390         png_init_io(png, fp);
 391         png_set_sig_bytes(png, 8);
 392         png_read_info(png, info);
 393         png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
 394
 395         if (pinfo != NULL) {
 396                 pinfo->Width  = width;
 397                 pinfo->Height = height;
 398                 pinfo->Depth  = depth;
 399         }
 400
 401         if (MaxTextureSize == 0)
 402                 glGetIntegerv(GL_MAX_TEXTURE_SIZE, &MaxTextureSize);
 403
 404         #ifdef SUPPORTS_PALETTE_EXT
 405         #ifdef _WIN32
 406                 if (PalettedTextures == -1)
 407                         PalettedTextures = ExtSupported("GL_EXT_paletted_texture") && (strstr((const char *) glGetString(GL_VERSION), "1.1.0 3Dfx Beta") == NULL);
 408
 409                 if (PalettedTextures) {
 410                         if (glColorTableEXT == NULL) {
 411                                 glColorTableEXT = (PFNGLCOLORTABLEEXTPROC) wglGetProcAddress("glColorTableEXT");
 412                                 if (glColorTableEXT == NULL)
 413                                         PalettedTextures = 0;
 414                         }
 415                 }
 416         #endif
 417         #endif
 418
 419         if (PalettedTextures == -1)
 420                 PalettedTextures = 0;
 421
 422         if (color == PNG_COLOR_TYPE_GRAY || color == PNG_COLOR_TYPE_GRAY_ALPHA)
 423                 png_set_gray_to_rgb(png);
 424
 425         if (color&PNG_COLOR_MASK_ALPHA && trans != PNG_ALPHA) {
 426                 png_set_strip_alpha(png);
 427                 color &= ~PNG_COLOR_MASK_ALPHA;
 428         }
 429
 430         if (!(PalettedTextures && mipmap >= 0 && trans == PNG_SOLID))
 431                 if (color == PNG_COLOR_TYPE_PALETTE)
 432                         png_set_expand(png);
 433
 434         /*--GAMMA--*/
 435         checkForGammaEnv();
 436         if (png_get_gAMA(png, info, &fileGamma))
 437                 png_set_gamma(png, screenGamma, fileGamma);
 438         else
 439                 png_set_gamma(png, screenGamma, 1.0/2.2);
 440
 441         png_read_update_info(png, info);
 442
 443         data = (png_bytep) malloc(png_get_rowbytes(png, info)*height);
 444         row_p = (png_bytep *) malloc(sizeof(png_bytep)*height);
 445
 446         for (i = 0; i < height; i++) {
 447                 if (StandardOrientation)
 448                         row_p[height - 1 - i] = &data[png_get_rowbytes(png, info)*i];
 449                 else
 450                         row_p[i] = &data[png_get_rowbytes(png, info)*i];
 451         }
 452
 453         png_read_image(png, row_p);
 454         free(row_p);
 455
 456         rw = SafeSize(width), rh = SafeSize(height);
 457
 458         if (rw != width || rh != height) {
 459                 const int channels = png_get_rowbytes(png, info)/width;
 460
 461                 data2 = (png_bytep) malloc(rw*rh*channels);
 462
 463                 /* Doesn't work on certain sizes */
 464 /*              if (gluScaleImage(glformat, width, height, GL_UNSIGNED_BYTE, data, rw, rh, GL_UNSIGNED_BYTE, data2) != 0)
 465                         return 0;
 466 */
 467                 Resize(channels, data, width, height, data2, rw, rh);
 468
 469                 width = rw, height = rh;
 470                 free(data);
 471                 data = data2;
 472         }
 473
 474         { /* OpenGL stuff */
 475                 glGetIntegerv(GL_PACK_ALIGNMENT, &pack);
 476                 glGetIntegerv(GL_UNPACK_ALIGNMENT, &unpack);
 477                 glPixelStorei(GL_PACK_ALIGNMENT, 1);
 478                 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 479
 480                 #ifdef SUPPORTS_PALETTE_EXT
 481                 if (PalettedTextures && mipmap >= 0 && trans == PNG_SOLID && color == PNG_COLOR_TYPE_PALETTE) {
 482                         png_colorp pal;
 483                         int cols;
 484                         GLint intf;
 485
 486                         if (pinfo != NULL) pinfo->Alpha = 0;
 487                         png_get_PLTE(png, info, &pal, &cols);
 488
 489                         switch (cols) {
 490                                 case 1<<1:  intf = GL_COLOR_INDEX1_EXT;  break;
 491                                 case 1<<2:  intf = GL_COLOR_INDEX2_EXT;  break;
 492                                 case 1<<4:  intf = GL_COLOR_INDEX4_EXT;  break;
 493                                 case 1<<8:  intf = GL_COLOR_INDEX8_EXT;  break;
 494                                 case 1<<12: intf = GL_COLOR_INDEX12_EXT; break;
 495                                 case 1<<16: intf = GL_COLOR_INDEX16_EXT; break;
 496                                 default:
 497                                         /*printf("Warning: Colour depth %i not recognised\n", cols);*/
 498                                         return 0;
 499                         }
 500                         glColorTableEXT(GL_TEXTURE_2D, GL_RGB8, cols, GL_RGB, GL_UNSIGNED_BYTE, pal);
 501                         glTexImage2D(GL_TEXTURE_2D, mipmap, intf, width, height, 0, GL_COLOR_INDEX, GL_UNSIGNED_BYTE, data);
 502                 }
 503                 else
 504                 #endif
 505                 if (trans == PNG_SOLID || trans == PNG_ALPHA || color == PNG_COLOR_TYPE_RGB_ALPHA || color == PNG_COLOR_TYPE_GRAY_ALPHA) {
 506                         GLenum glformat;
 507                         GLint glcomponent;
 508
 509                         switch (color) {
 510                                 case PNG_COLOR_TYPE_GRAY:
 511                                 case PNG_COLOR_TYPE_RGB:
 512                                 case PNG_COLOR_TYPE_PALETTE:
 513                                         glformat = GL_RGB;
 514                                         glcomponent = 3;
 515                                         if (pinfo != NULL) pinfo->Alpha = 0;
 516                                         break;
 517
 518                                 case PNG_COLOR_TYPE_GRAY_ALPHA:
 519                                 case PNG_COLOR_TYPE_RGB_ALPHA:
 520                                         glformat = GL_RGBA;
 521                                         glcomponent = 4;
 522                                         if (pinfo != NULL) pinfo->Alpha = 8;
 523                                         break;
 524
 525                                 default:
 526                                         /*puts("glformat not set");*/
 527                                         return 0;
 528                         }
 529
 530                         if (mipmap == PNG_BUILDMIPMAPS)
 531                                 Build2DMipmaps(glcomponent, width, height, glformat, data, 1);
 532                         else if (mipmap == PNG_SIMPLEMIPMAPS)
 533                                 Build2DMipmaps(glcomponent, width, height, glformat, data, 0);
 534                         else
 535                                 glTexImage2D(GL_TEXTURE_2D, mipmap, glcomponent, width, height, 0, glformat, GL_UNSIGNED_BYTE, data);
 536                 }
 537                 else {
 538                         png_bytep p, endp, q;
 539                         int r, g, b, a;
 540
 541                         p = data, endp = p+width*height*3;
 542                         q = data2 = (png_bytep) malloc(sizeof(png_byte)*width*height*4);
 543
 544                         if (pinfo != NULL) pinfo->Alpha = 8;
 545
 546                         #define FORSTART \
 547                                 do { \
 548                                         r = *p++; /*red  */ \
 549                                         g = *p++; /*green*/ \
 550                                         b = *p++; /*blue */ \
 551                                         *q++ = r; \
 552                                         *q++ = g; \
 553                                         *q++ = b;
 554
 555                         #define FOREND \
 556                                         q++; \
 557                                 } while (p != endp);
 558
 559                         #define ALPHA *q
 560
 561                         switch (trans) {
 562                                 case PNG_CALLBACK:
 563                                         FORSTART
 564                                                 ALPHA = AlphaCallback((unsigned char) r, (unsigned char) g, (unsigned char) b);
 565                                         FOREND
 566                                         break;
 567
 568                                 case PNG_STENCIL:
 569                                         FORSTART
 570                                                 if (r == StencilRed && g == StencilGreen && b == StencilBlue)
 571                                                         ALPHA = 0;
 572                                                 else
 573                                                         ALPHA = 255;
 574                                         FOREND
 575                                         break;
 576
 577                                 case PNG_BLEND1:
 578                                         FORSTART
 579                                                 a = r+g+b;
 580                                                 if (a > 255) ALPHA = 255; else ALPHA = a;
 581                                         FOREND
 582                                         break;
 583
 584                                 case PNG_BLEND2:
 585                                         FORSTART
 586                                                 a = r+g+b;
 587                                                 if (a > 255*2) ALPHA = 255; else ALPHA = a/2;
 588                                         FOREND
 589                                         break;
 590
 591                                 case PNG_BLEND3:
 592                                         FORSTART
 593                                                 ALPHA = (r+g+b)/3;
 594                                         FOREND
 595                                         break;
 596
 597                                 case PNG_BLEND4:
 598                                         FORSTART
 599                                                 a = r*r+g*g+b*b;
 600                                                 if (a > 255) ALPHA = 255; else ALPHA = a;
 601                                         FOREND
 602                                         break;
 603
 604                                 case PNG_BLEND5:
 605                                         FORSTART
 606                                                 a = r*r+g*g+b*b;
 607                                                 if (a > 255*2) ALPHA = 255; else ALPHA = a/2;
 608                                         FOREND
 609                                         break;
 610
 611                                 case PNG_BLEND6:
 612                                         FORSTART
 613                                                 a = r*r+g*g+b*b;
 614                                                 if (a > 255*3) ALPHA = 255; else ALPHA = a/3;
 615                                         FOREND
 616                                         break;
 617
 618                                 case PNG_BLEND7:
 619                                         FORSTART
 620                                                 a = r*r+g*g+b*b;
 621                                                 if (a > 255*255) ALPHA = 255; else ALPHA = (int) sqrt(a);
 622                                         FOREND
 623                                         break;
 624                         }
 625
 626                         #undef FORSTART
 627                         #undef FOREND
 628                         #undef ALPHA
 629
 630                         if (mipmap == PNG_BUILDMIPMAPS)
 631                                 Build2DMipmaps(4, width, height, GL_RGBA, data2, 1);
 632                         else if (mipmap == PNG_SIMPLEMIPMAPS)
 633                                 Build2DMipmaps(4, width, height, GL_RGBA, data2, 0);
 634                         else
 635                                 glTexImage2D(GL_TEXTURE_2D, mipmap, 4, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data2);
 636
 637                         free(data2);
 638                 }
 639
 640                 glPixelStorei(GL_PACK_ALIGNMENT, pack);
 641                 glPixelStorei(GL_UNPACK_ALIGNMENT, unpack);
 642         } /* OpenGL end */
 643
 644    png_read_end(png, endinfo);
 645         png_destroy_read_struct(&png, &info, &endinfo);
 646
 647         free(data);
 648
 649         return 1;
 650 }
 651
 652 static unsigned int SetParams(int wrapst, int magfilter, int minfilter) {
 653         unsigned int id;
 654
 655         glGenTextures(1, &id);
 656         glBindTexture(GL_TEXTURE_2D, id);
 657
 658         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapst);
 659         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapst);
 660
 661         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magfilter);
 662         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minfilter);
 663
 664         return id;
 665 }
 666
 667 unsigned int APIENTRY pngBind(const char *filename, int mipmap, int trans, pngInfo *info, int wrapst, int minfilter, int magfilter) {
 668         unsigned int id = SetParams(wrapst, magfilter, minfilter);
 669
 670         if (id != 0 && pngLoad(filename, mipmap, trans, info))
 671                 return id;
 672         return 0;
 673 }
 674
 675 unsigned int APIENTRY pngBindF(FILE *file, int mipmap, int trans, pngInfo *info, int wrapst, int minfilter, int magfilter) {
 676         unsigned int id = SetParams(wrapst, magfilter, minfilter);
 677
 678         if (id != 0 && pngLoadF(file, mipmap, trans, info))
 679                 return id;
 680         return 0;
 681 }
 682
 683 void APIENTRY pngSetStencil(unsigned char red, unsigned char green, unsigned char blue) {
 684         StencilRed = red, StencilGreen = green, StencilBlue = blue;
 685 }
 686
 687 void APIENTRY pngSetAlphaCallback(unsigned char (*callback)(unsigned char red, unsigned char green, unsigned char blue)) {
 688         if (callback == NULL)
 689                 AlphaCallback = DefaultAlphaCallback;
 690         else
 691                 AlphaCallback = callback;
 692 }
 693
 694 void APIENTRY pngSetViewingGamma(double viewingGamma) {
 695         if(viewingGamma > 0) {
 696                 gammaExplicit = 1;
 697                 screenGamma = 2.2/viewingGamma;
 698         }
 699         else {
 700                 gammaExplicit = 0;
 701                 screenGamma = 2.2;
 702         }
 703 }
 704
 705 void APIENTRY pngSetStandardOrientation(int standardorientation) {
 706         StandardOrientation = standardorientation;
 707 }