src/glu/mesa/mipmap.c

   1
   2 /*
   3  * Mesa 3-D graphics library
   4  * Version:  3.4
   5  * Copyright (C) 1995-2000  Brian Paul
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Library General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Library General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Library General Public
  18  * License along with this library; if not, write to the Free
  19  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22
  23 #ifdef PC_HEADER
  24 #include "all.h"
  25 #else
  26 #include <assert.h>
  27 #include <math.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include "gluP.h"
  31 #endif
  32
  33
  34 /*
  35  * Compute ceiling of integer quotient of A divided by B:
  36  */
  37 #define CEILING( A, B )  ( (A) % (B) == 0 ? (A)/(B) : (A)/(B)+1 )
  38
  39
  40
  41 #ifdef EPSILON
  42 #undef EPSILON
  43 #endif
  44 #define EPSILON 0.001
  45
  46
  47 /* To work around optimizer bug in MSVC4.1 */
  48 #if defined(__WIN32__) && !defined(OPENSTEP)
  49 void
  50 dummy(GLuint j, GLuint k)
  51 {
  52 }
  53 #else
  54 #define dummy(J, K)
  55 #endif
  56
  57
  58 GLint GLAPIENTRY
  59 gluScaleImage(GLenum format,
  60               GLsizei widthin, GLsizei heightin,
  61               GLenum typein, const void *datain,
  62               GLsizei widthout, GLsizei heightout,
  63               GLenum typeout, void *dataout)
  64 {
  65    GLint components, i, j, k;
  66    GLfloat *tempin, *tempout;
  67    GLfloat sx, sy;
  68    GLint unpackrowlength, unpackalignment, unpackskiprows, unpackskippixels;
  69    GLint packrowlength, packalignment, packskiprows, packskippixels;
  70    GLint sizein, sizeout;
  71    GLint rowstride, rowlen;
  72
  73
  74    /* Determine number of components per pixel */
  75    switch (format) {
  76    case GL_COLOR_INDEX:
  77    case GL_STENCIL_INDEX:
  78    case GL_DEPTH_COMPONENT:
  79    case GL_RED:
  80    case GL_GREEN:
  81    case GL_BLUE:
  82    case GL_ALPHA:
  83    case GL_LUMINANCE:
  84       components = 1;
  85       break;
  86    case GL_LUMINANCE_ALPHA:
  87       components = 2;
  88       break;
  89    case GL_RGB:
  90    case GL_BGR:
  91       components = 3;
  92       break;
  93    case GL_RGBA:
  94    case GL_BGRA:
  95 #ifdef GL_EXT_abgr
  96    case GL_ABGR_EXT:
  97 #endif
  98       components = 4;
  99       break;
 100    default:
 101       return GLU_INVALID_ENUM;
 102    }
 103
 104    /* Determine bytes per input datum */
 105    switch (typein) {
 106    case GL_UNSIGNED_BYTE:
 107       sizein = sizeof(GLubyte);
 108       break;
 109    case GL_BYTE:
 110       sizein = sizeof(GLbyte);
 111       break;
 112    case GL_UNSIGNED_SHORT:
 113       sizein = sizeof(GLushort);
 114       break;
 115    case GL_SHORT:
 116       sizein = sizeof(GLshort);
 117       break;
 118    case GL_UNSIGNED_INT:
 119       sizein = sizeof(GLuint);
 120       break;
 121    case GL_INT:
 122       sizein = sizeof(GLint);
 123       break;
 124    case GL_FLOAT:
 125       sizein = sizeof(GLfloat);
 126       break;
 127    case GL_BITMAP:
 128       /* not implemented yet */
 129    default:
 130       return GL_INVALID_ENUM;
 131    }
 132
 133    /* Determine bytes per output datum */
 134    switch (typeout) {
 135    case GL_UNSIGNED_BYTE:
 136       sizeout = sizeof(GLubyte);
 137       break;
 138    case GL_BYTE:
 139       sizeout = sizeof(GLbyte);
 140       break;
 141    case GL_UNSIGNED_SHORT:
 142       sizeout = sizeof(GLushort);
 143       break;
 144    case GL_SHORT:
 145       sizeout = sizeof(GLshort);
 146       break;
 147    case GL_UNSIGNED_INT:
 148       sizeout = sizeof(GLuint);
 149       break;
 150    case GL_INT:
 151       sizeout = sizeof(GLint);
 152       break;
 153    case GL_FLOAT:
 154       sizeout = sizeof(GLfloat);
 155       break;
 156    case GL_BITMAP:
 157       /* not implemented yet */
 158    default:
 159       return GL_INVALID_ENUM;
 160    }
 161
 162    /* Get glPixelStore state */
 163    glGetIntegerv(GL_UNPACK_ROW_LENGTH, &unpackrowlength);
 164    glGetIntegerv(GL_UNPACK_ALIGNMENT, &unpackalignment);
 165    glGetIntegerv(GL_UNPACK_SKIP_ROWS, &unpackskiprows);
 166    glGetIntegerv(GL_UNPACK_SKIP_PIXELS, &unpackskippixels);
 167    glGetIntegerv(GL_PACK_ROW_LENGTH, &packrowlength);
 168    glGetIntegerv(GL_PACK_ALIGNMENT, &packalignment);
 169    glGetIntegerv(GL_PACK_SKIP_ROWS, &packskiprows);
 170    glGetIntegerv(GL_PACK_SKIP_PIXELS, &packskippixels);
 171
 172    /* Allocate storage for intermediate images */
 173    tempin = (GLfloat *) malloc(widthin * heightin
 174                                * components * sizeof(GLfloat));
 175    if (!tempin) {
 176       return GLU_OUT_OF_MEMORY;
 177    }
 178    tempout = (GLfloat *) malloc(widthout * heightout
 179                                 * components * sizeof(GLfloat));
 180    if (!tempout) {
 181       free(tempin);
 182       return GLU_OUT_OF_MEMORY;
 183    }
 184
 185
 186    /*
 187     * Unpack the pixel data and convert to floating point
 188     */
 189
 190    if (unpackrowlength > 0) {
 191       rowlen = unpackrowlength;
 192    }
 193    else {
 194       rowlen = widthin;
 195    }
 196    if (sizein >= unpackalignment) {
 197       rowstride = components * rowlen;
 198    }
 199    else {
 200       rowstride = unpackalignment / sizein
 201          * CEILING(components * rowlen * sizein, unpackalignment);
 202    }
 203
 204    switch (typein) {
 205    case GL_UNSIGNED_BYTE:
 206       k = 0;
 207       for (i = 0; i < heightin; i++) {
 208          GLubyte *ubptr = (GLubyte *) datain
 209             + i * rowstride
 210             + unpackskiprows * rowstride + unpackskippixels * components;
 211          for (j = 0; j < widthin * components; j++) {
 212             dummy(j, k);
 213             tempin[k++] = (GLfloat) * ubptr++;
 214          }
 215       }
 216       break;
 217    case GL_BYTE:
 218       k = 0;
 219       for (i = 0; i < heightin; i++) {
 220          GLbyte *bptr = (GLbyte *) datain
 221             + i * rowstride
 222             + unpackskiprows * rowstride + unpackskippixels * components;
 223          for (j = 0; j < widthin * components; j++) {
 224             dummy(j, k);
 225             tempin[k++] = (GLfloat) * bptr++;
 226          }
 227       }
 228       break;
 229    case GL_UNSIGNED_SHORT:
 230       k = 0;
 231       for (i = 0; i < heightin; i++) {
 232          GLushort *usptr = (GLushort *) datain
 233             + i * rowstride
 234             + unpackskiprows * rowstride + unpackskippixels * components;
 235          for (j = 0; j < widthin * components; j++) {
 236             dummy(j, k);
 237             tempin[k++] = (GLfloat) * usptr++;
 238          }
 239       }
 240       break;
 241    case GL_SHORT:
 242       k = 0;
 243       for (i = 0; i < heightin; i++) {
 244          GLshort *sptr = (GLshort *) datain
 245             + i * rowstride
 246             + unpackskiprows * rowstride + unpackskippixels * components;
 247          for (j = 0; j < widthin * components; j++) {
 248             dummy(j, k);
 249             tempin[k++] = (GLfloat) * sptr++;
 250          }
 251       }
 252       break;
 253    case GL_UNSIGNED_INT:
 254       k = 0;
 255       for (i = 0; i < heightin; i++) {
 256          GLuint *uiptr = (GLuint *) datain
 257             + i * rowstride
 258             + unpackskiprows * rowstride + unpackskippixels * components;
 259          for (j = 0; j < widthin * components; j++) {
 260             dummy(j, k);
 261             tempin[k++] = (GLfloat) * uiptr++;
 262          }
 263       }
 264       break;
 265    case GL_INT:
 266       k = 0;
 267       for (i = 0; i < heightin; i++) {
 268          GLint *iptr = (GLint *) datain
 269             + i * rowstride
 270             + unpackskiprows * rowstride + unpackskippixels * components;
 271          for (j = 0; j < widthin * components; j++) {
 272             dummy(j, k);
 273             tempin[k++] = (GLfloat) * iptr++;
 274          }
 275       }
 276       break;
 277    case GL_FLOAT:
 278       k = 0;
 279       for (i = 0; i < heightin; i++) {
 280          GLfloat *fptr = (GLfloat *) datain
 281             + i * rowstride
 282             + unpackskiprows * rowstride + unpackskippixels * components;
 283          for (j = 0; j < widthin * components; j++) {
 284             dummy(j, k);
 285             tempin[k++] = *fptr++;
 286          }
 287       }
 288       break;
 289    default:
 290       return GLU_INVALID_ENUM;
 291    }
 292
 293
 294    /*
 295     * Scale the image!
 296     */
 297
 298    if (widthout > 1)
 299       sx = (GLfloat) (widthin - 1) / (GLfloat) (widthout - 1);
 300    else
 301       sx = (GLfloat) (widthin - 1);
 302    if (heightout > 1)
 303       sy = (GLfloat) (heightin - 1) / (GLfloat) (heightout - 1);
 304    else
 305       sy = (GLfloat) (heightin - 1);
 306
 307 /*#define POINT_SAMPLE*/
 308 #ifdef POINT_SAMPLE
 309    for (i = 0; i < heightout; i++) {
 310       GLint ii = i * sy;
 311       for (j = 0; j < widthout; j++) {
 312          GLint jj = j * sx;
 313
 314          GLfloat *src = tempin + (ii * widthin + jj) * components;
 315          GLfloat *dst = tempout + (i * widthout + j) * components;
 316
 317          for (k = 0; k < components; k++) {
 318             *dst++ = *src++;
 319          }
 320       }
 321    }
 322 #else
 323    if (sx < 1.0 && sy < 1.0) {
 324       /* magnify both width and height:  use weighted sample of 4 pixels */
 325       GLint i0, i1, j0, j1;
 326       GLfloat alpha, beta;
 327       GLfloat *src00, *src01, *src10, *src11;
 328       GLfloat s1, s2;
 329       GLfloat *dst;
 330
 331       for (i = 0; i < heightout; i++) {
 332          i0 = i * sy;
 333          i1 = i0 + 1;
 334          if (i1 >= heightin)
 335             i1 = heightin - 1;
 336 /*       i1 = (i+1) * sy - EPSILON;*/
 337          alpha = i * sy - i0;
 338          for (j = 0; j < widthout; j++) {
 339             j0 = j * sx;
 340             j1 = j0 + 1;
 341             if (j1 >= widthin)
 342                j1 = widthin - 1;
 343 /*          j1 = (j+1) * sx - EPSILON; */
 344             beta = j * sx - j0;
 345
 346             /* compute weighted average of pixels in rect (i0,j0)-(i1,j1) */
 347             src00 = tempin + (i0 * widthin + j0) * components;
 348             src01 = tempin + (i0 * widthin + j1) * components;
 349             src10 = tempin + (i1 * widthin + j0) * components;
 350             src11 = tempin + (i1 * widthin + j1) * components;
 351
 352             dst = tempout + (i * widthout + j) * components;
 353
 354             for (k = 0; k < components; k++) {
 355                s1 = *src00++ * (1.0 - beta) + *src01++ * beta;
 356                s2 = *src10++ * (1.0 - beta) + *src11++ * beta;
 357                *dst++ = s1 * (1.0 - alpha) + s2 * alpha;
 358             }
 359          }
 360       }
 361    }
 362    else {
 363       /* shrink width and/or height:  use an unweighted box filter */
 364       GLint i0, i1;
 365       GLint j0, j1;
 366       GLint ii, jj;
 367       GLfloat sum, *dst;
 368
 369       for (i = 0; i < heightout; i++) {
 370          i0 = i * sy;
 371          i1 = i0 + 1;
 372          if (i1 >= heightin)
 373             i1 = heightin - 1;
 374 /*       i1 = (i+1) * sy - EPSILON; */
 375          for (j = 0; j < widthout; j++) {
 376             j0 = j * sx;
 377             j1 = j0 + 1;
 378             if (j1 >= widthin)
 379                j1 = widthin - 1;
 380 /*          j1 = (j+1) * sx - EPSILON; */
 381
 382             dst = tempout + (i * widthout + j) * components;
 383
 384             /* compute average of pixels in the rectangle (i0,j0)-(i1,j1) */
 385             for (k = 0; k < components; k++) {
 386                sum = 0.0;
 387                for (ii = i0; ii <= i1; ii++) {
 388                   for (jj = j0; jj <= j1; jj++) {
 389                      sum += *(tempin + (ii * widthin + jj) * components + k);
 390                   }
 391                }
 392                sum /= (j1 - j0 + 1) * (i1 - i0 + 1);
 393                *dst++ = sum;
 394             }
 395          }
 396       }
 397    }
 398 #endif
 399
 400
 401    /*
 402     * Return output image
 403     */
 404
 405    if (packrowlength > 0) {
 406       rowlen = packrowlength;
 407    }
 408    else {
 409       rowlen = widthout;
 410    }
 411    if (sizeout >= packalignment) {
 412       rowstride = components * rowlen;
 413    }
 414    else {
 415       rowstride = packalignment / sizeout
 416          * CEILING(components * rowlen * sizeout, packalignment);
 417    }
 418
 419    switch (typeout) {
 420    case GL_UNSIGNED_BYTE:
 421       k = 0;
 422       for (i = 0; i < heightout; i++) {
 423          GLubyte *ubptr = (GLubyte *) dataout
 424             + i * rowstride
 425             + packskiprows * rowstride + packskippixels * components;
 426          for (j = 0; j < widthout * components; j++) {
 427             dummy(j, k + i);
 428             *ubptr++ = (GLubyte) tempout[k++];
 429          }
 430       }
 431       break;
 432    case GL_BYTE:
 433       k = 0;
 434       for (i = 0; i < heightout; i++) {
 435          GLbyte *bptr = (GLbyte *) dataout
 436             + i * rowstride
 437             + packskiprows * rowstride + packskippixels * components;
 438          for (j = 0; j < widthout * components; j++) {
 439             dummy(j, k + i);
 440             *bptr++ = (GLbyte) tempout[k++];
 441          }
 442       }
 443       break;
 444    case GL_UNSIGNED_SHORT:
 445       k = 0;
 446       for (i = 0; i < heightout; i++) {
 447          GLushort *usptr = (GLushort *) dataout
 448             + i * rowstride
 449             + packskiprows * rowstride + packskippixels * components;
 450          for (j = 0; j < widthout * components; j++) {
 451             dummy(j, k + i);
 452             *usptr++ = (GLushort) tempout[k++];
 453          }
 454       }
 455       break;
 456    case GL_SHORT:
 457       k = 0;
 458       for (i = 0; i < heightout; i++) {
 459          GLshort *sptr = (GLshort *) dataout
 460             + i * rowstride
 461             + packskiprows * rowstride + packskippixels * components;
 462          for (j = 0; j < widthout * components; j++) {
 463             dummy(j, k + i);
 464             *sptr++ = (GLshort) tempout[k++];
 465          }
 466       }
 467       break;
 468    case GL_UNSIGNED_INT:
 469       k = 0;
 470       for (i = 0; i < heightout; i++) {
 471          GLuint *uiptr = (GLuint *) dataout
 472             + i * rowstride
 473             + packskiprows * rowstride + packskippixels * components;
 474          for (j = 0; j < widthout * components; j++) {
 475             dummy(j, k + i);
 476             *uiptr++ = (GLuint) tempout[k++];
 477          }
 478       }
 479       break;
 480    case GL_INT:
 481       k = 0;
 482       for (i = 0; i < heightout; i++) {
 483          GLint *iptr = (GLint *) dataout
 484             + i * rowstride
 485             + packskiprows * rowstride + packskippixels * components;
 486          for (j = 0; j < widthout * components; j++) {
 487             dummy(j, k + i);
 488             *iptr++ = (GLint) tempout[k++];
 489          }
 490       }
 491       break;
 492    case GL_FLOAT:
 493       k = 0;
 494       for (i = 0; i < heightout; i++) {
 495          GLfloat *fptr = (GLfloat *) dataout
 496             + i * rowstride
 497             + packskiprows * rowstride + packskippixels * components;
 498          for (j = 0; j < widthout * components; j++) {
 499             dummy(j, k + i);
 500             *fptr++ = tempout[k++];
 501          }
 502       }
 503       break;
 504    default:
 505       return GLU_INVALID_ENUM;
 506    }
 507
 508
 509    /* free temporary image storage */
 510    free(tempin);
 511    free(tempout);
 512
 513    return 0;
 514 }
 515
 516
 517
 518 /*
 519  * Return the largest k such that 2^k <= n.
 520  */
 521 static GLint
 522 ilog2(GLint n)
 523 {
 524    GLint k;
 525
 526    if (n <= 0)
 527       return 0;
 528    for (k = 0; n >>= 1; k++);
 529    return k;
 530 }
 531
 532
 533
 534 /*
 535  * Find the value nearest to n which is also a power of two.
 536  */
 537 static GLint
 538 round2(GLint n)
 539 {
 540    GLint m;
 541
 542    for (m = 1; m < n; m *= 2);
 543
 544    /* m>=n */
 545    if (m - n <= n - m / 2) {
 546       return m;
 547    }
 548    else {
 549       return m / 2;
 550    }
 551 }
 552
 553
 554 /*
 555  * Given an pixel format and datatype, return the number of bytes to
 556  * store one pixel.
 557  */
 558 static GLint
 559 bytes_per_pixel(GLenum format, GLenum type)
 560 {
 561    GLint n, m;
 562
 563    switch (format) {
 564    case GL_COLOR_INDEX:
 565    case GL_STENCIL_INDEX:
 566    case GL_DEPTH_COMPONENT:
 567    case GL_RED:
 568    case GL_GREEN:
 569    case GL_BLUE:
 570    case GL_ALPHA:
 571    case GL_LUMINANCE:
 572       n = 1;
 573       break;
 574    case GL_LUMINANCE_ALPHA:
 575       n = 2;
 576       break;
 577    case GL_RGB:
 578    case GL_BGR:
 579       n = 3;
 580       break;
 581    case GL_RGBA:
 582    case GL_BGRA:
 583 #ifdef GL_EXT_abgr
 584    case GL_ABGR_EXT:
 585 #endif
 586       n = 4;
 587       break;
 588    default:
 589       n = 0;
 590    }
 591
 592    switch (type) {
 593    case GL_UNSIGNED_BYTE:
 594       m = sizeof(GLubyte);
 595       break;
 596    case GL_BYTE:
 597       m = sizeof(GLbyte);
 598       break;
 599    case GL_BITMAP:
 600       m = 1;
 601       break;
 602    case GL_UNSIGNED_SHORT:
 603       m = sizeof(GLushort);
 604       break;
 605    case GL_SHORT:
 606       m = sizeof(GLshort);
 607       break;
 608    case GL_UNSIGNED_INT:
 609       m = sizeof(GLuint);
 610       break;
 611    case GL_INT:
 612       m = sizeof(GLint);
 613       break;
 614    case GL_FLOAT:
 615       m = sizeof(GLfloat);
 616       break;
 617    default:
 618       m = 0;
 619    }
 620
 621    return n * m;
 622 }
 623
 624
 625
 626 /*
 627  * WARNING: This function isn't finished and has never been tested!!!!
 628  */
 629 GLint GLAPIENTRY
 630 gluBuild1DMipmaps(GLenum target, GLint components,
 631                   GLsizei width, GLenum format, GLenum type, const void *data)
 632 {
 633    GLubyte *texture;
 634    GLint levels, max_levels;
 635    GLint new_width, max_width;
 636    GLint i, j, k, l;
 637
 638    if (width < 1)
 639       return GLU_INVALID_VALUE;
 640
 641    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_width);
 642    max_levels = ilog2(max_width) + 1;
 643
 644    /* Compute how many mipmap images to make */
 645    levels = ilog2(width) + 1;
 646    if (levels > max_levels) {
 647       levels = max_levels;
 648    }
 649
 650    new_width = 1 << (levels - 1);
 651
 652    texture = (GLubyte *) malloc(new_width * components);
 653    if (!texture) {
 654       return GLU_OUT_OF_MEMORY;
 655    }
 656
 657    if (width != new_width) {
 658       /* initial rescaling */
 659       switch (type) {
 660       case GL_UNSIGNED_BYTE:
 661          {
 662             GLubyte *ub_data = (GLubyte *) data;
 663             for (i = 0; i < new_width; i++) {
 664                j = i * width / new_width;
 665                for (k = 0; k < components; k++) {
 666                   texture[i * components + k] = ub_data[j * components + k];
 667                }
 668             }
 669          }
 670          break;
 671       default:
 672          /* Not implemented */
 673          return GLU_ERROR;
 674       }
 675    }
 676
 677    /* generate and load mipmap images */
 678    for (l = 0; l < levels; l++) {
 679       glTexImage1D(GL_TEXTURE_1D, l, components, new_width, 0,
 680                    format, GL_UNSIGNED_BYTE, texture);
 681
 682       /* Scale image down to 1/2 size */
 683       new_width = new_width / 2;
 684       for (i = 0; i < new_width; i++) {
 685          for (k = 0; k < components; k++) {
 686             GLint sample1, sample2;
 687             sample1 = (GLint) texture[i * 2 * components + k];
 688             sample2 = (GLint) texture[(i * 2 + 1) * components + k];
 689             texture[i * components + k] = (GLubyte) ((sample1 + sample2) / 2);
 690          }
 691       }
 692    }
 693
 694    free(texture);
 695
 696    return 0;
 697 }
 698
 699
 700
 701 GLint GLAPIENTRY
 702 gluBuild2DMipmaps(GLenum target, GLint components,
 703                   GLsizei width, GLsizei height, GLenum format,
 704                   GLenum type, const void *data)
 705 {
 706    GLint w, h, maxsize;
 707    void *image, *newimage;
 708    GLint neww, newh, level, bpp;
 709    int error;
 710    GLboolean done;
 711    GLint retval = 0;
 712    GLint unpackrowlength, unpackalignment, unpackskiprows, unpackskippixels;
 713    GLint packrowlength, packalignment, packskiprows, packskippixels;
 714
 715    if (width < 1 || height < 1)
 716       return GLU_INVALID_VALUE;
 717
 718    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxsize);
 719
 720    w = round2(width);
 721    if (w > maxsize) {
 722       w = maxsize;
 723    }
 724    h = round2(height);
 725    if (h > maxsize) {
 726       h = maxsize;
 727    }
 728
 729    bpp = bytes_per_pixel(format, type);
 730    if (bpp == 0) {
 731       /* probably a bad format or type enum */
 732       return GLU_INVALID_ENUM;
 733    }
 734
 735    /* Get current glPixelStore values */
 736    glGetIntegerv(GL_UNPACK_ROW_LENGTH, &unpackrowlength);
 737    glGetIntegerv(GL_UNPACK_ALIGNMENT, &unpackalignment);
 738    glGetIntegerv(GL_UNPACK_SKIP_ROWS, &unpackskiprows);
 739    glGetIntegerv(GL_UNPACK_SKIP_PIXELS, &unpackskippixels);
 740    glGetIntegerv(GL_PACK_ROW_LENGTH, &packrowlength);
 741    glGetIntegerv(GL_PACK_ALIGNMENT, &packalignment);
 742    glGetIntegerv(GL_PACK_SKIP_ROWS, &packskiprows);
 743    glGetIntegerv(GL_PACK_SKIP_PIXELS, &packskippixels);
 744
 745    /* set pixel packing */
 746    glPixelStorei(GL_PACK_ROW_LENGTH, 0);
 747    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 748    glPixelStorei(GL_PACK_SKIP_ROWS, 0);
 749    glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
 750
 751    done = GL_FALSE;
 752
 753    if (w != width || h != height) {
 754       /* must rescale image to get "top" mipmap texture image */
 755       image = malloc((w + 4) * h * bpp);
 756       if (!image) {
 757          return GLU_OUT_OF_MEMORY;
 758       }
 759       error = gluScaleImage(format, width, height, type, data,
 760                             w, h, type, image);
 761       if (error) {
 762          retval = error;
 763          done = GL_TRUE;
 764       }
 765    }
 766    else {
 767       image = (void *) data;
 768    }
 769
 770    level = 0;
 771    while (!done) {
 772       if (image != data) {
 773          /* set pixel unpacking */
 774          glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
 775          glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 776          glPixelStorei(GL_UNPACK_SKIP_ROWS, 0);
 777          glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
 778       }
 779
 780       glTexImage2D(target, level, components, w, h, 0, format, type, image);
 781
 782       if (w == 1 && h == 1)
 783          break;
 784
 785       neww = (w < 2) ? 1 : w / 2;
 786       newh = (h < 2) ? 1 : h / 2;
 787       newimage = malloc((neww + 4) * newh * bpp);
 788       if (!newimage) {
 789          return GLU_OUT_OF_MEMORY;
 790       }
 791
 792       error = gluScaleImage(format, w, h, type, image,
 793                             neww, newh, type, newimage);
 794       if (error) {
 795          retval = error;
 796          done = GL_TRUE;
 797       }
 798
 799       if (image != data) {
 800          free(image);
 801       }
 802       image = newimage;
 803
 804       w = neww;
 805       h = newh;
 806       level++;
 807    }
 808
 809    if (image != data) {
 810       free(image);
 811    }
 812
 813    /* Restore original glPixelStore state */
 814    glPixelStorei(GL_UNPACK_ROW_LENGTH, unpackrowlength);
 815    glPixelStorei(GL_UNPACK_ALIGNMENT, unpackalignment);
 816    glPixelStorei(GL_UNPACK_SKIP_ROWS, unpackskiprows);
 817    glPixelStorei(GL_UNPACK_SKIP_PIXELS, unpackskippixels);
 818    glPixelStorei(GL_PACK_ROW_LENGTH, packrowlength);
 819    glPixelStorei(GL_PACK_ALIGNMENT, packalignment);
 820    glPixelStorei(GL_PACK_SKIP_ROWS, packskiprows);
 821    glPixelStorei(GL_PACK_SKIP_PIXELS, packskippixels);
 822
 823    return retval;
 824 }