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       {
 291          free(tempin);
 292          free(tempout);
 293          return GLU_INVALID_ENUM;
 294       }
 295    }
 296
 297
 298    /*
 299     * Scale the image!
 300     */
 301
 302    if (widthout > 1)
 303       sx = (GLfloat) (widthin - 1) / (GLfloat) (widthout - 1);
 304    else
 305       sx = (GLfloat) (widthin - 1);
 306    if (heightout > 1)
 307       sy = (GLfloat) (heightin - 1) / (GLfloat) (heightout - 1);
 308    else
 309       sy = (GLfloat) (heightin - 1);
 310
 311 /*#define POINT_SAMPLE*/
 312 #ifdef POINT_SAMPLE
 313    for (i = 0; i < heightout; i++) {
 314       GLint ii = i * sy;
 315       for (j = 0; j < widthout; j++) {
 316          GLint jj = j * sx;
 317
 318          GLfloat *src = tempin + (ii * widthin + jj) * components;
 319          GLfloat *dst = tempout + (i * widthout + j) * components;
 320
 321          for (k = 0; k < components; k++) {
 322             *dst++ = *src++;
 323          }
 324       }
 325    }
 326 #else
 327    if (sx < 1.0 && sy < 1.0) {
 328       /* magnify both width and height:  use weighted sample of 4 pixels */
 329       GLint i0, i1, j0, j1;
 330       GLfloat alpha, beta;
 331       GLfloat *src00, *src01, *src10, *src11;
 332       GLfloat s1, s2;
 333       GLfloat *dst;
 334
 335       for (i = 0; i < heightout; i++) {
 336          i0 = i * sy;
 337          i1 = i0 + 1;
 338          if (i1 >= heightin)
 339             i1 = heightin - 1;
 340 /*       i1 = (i+1) * sy - EPSILON;*/
 341          alpha = i * sy - i0;
 342          for (j = 0; j < widthout; j++) {
 343             j0 = j * sx;
 344             j1 = j0 + 1;
 345             if (j1 >= widthin)
 346                j1 = widthin - 1;
 347 /*          j1 = (j+1) * sx - EPSILON; */
 348             beta = j * sx - j0;
 349
 350             /* compute weighted average of pixels in rect (i0,j0)-(i1,j1) */
 351             src00 = tempin + (i0 * widthin + j0) * components;
 352             src01 = tempin + (i0 * widthin + j1) * components;
 353             src10 = tempin + (i1 * widthin + j0) * components;
 354             src11 = tempin + (i1 * widthin + j1) * components;
 355
 356             dst = tempout + (i * widthout + j) * components;
 357
 358             for (k = 0; k < components; k++) {
 359                s1 = *src00++ * (1.0 - beta) + *src01++ * beta;
 360                s2 = *src10++ * (1.0 - beta) + *src11++ * beta;
 361                *dst++ = s1 * (1.0 - alpha) + s2 * alpha;
 362             }
 363          }
 364       }
 365    }
 366    else {
 367       /* shrink width and/or height:  use an unweighted box filter */
 368       GLint i0, i1;
 369       GLint j0, j1;
 370       GLint ii, jj;
 371       GLfloat sum, *dst;
 372
 373       for (i = 0; i < heightout; i++) {
 374          i0 = i * sy;
 375          i1 = i0 + 1;
 376          if (i1 >= heightin)
 377             i1 = heightin - 1;
 378 /*       i1 = (i+1) * sy - EPSILON; */
 379          for (j = 0; j < widthout; j++) {
 380             j0 = j * sx;
 381             j1 = j0 + 1;
 382             if (j1 >= widthin)
 383                j1 = widthin - 1;
 384 /*          j1 = (j+1) * sx - EPSILON; */
 385
 386             dst = tempout + (i * widthout + j) * components;
 387
 388             /* compute average of pixels in the rectangle (i0,j0)-(i1,j1) */
 389             for (k = 0; k < components; k++) {
 390                sum = 0.0;
 391                for (ii = i0; ii <= i1; ii++) {
 392                   for (jj = j0; jj <= j1; jj++) {
 393                      sum += *(tempin + (ii * widthin + jj) * components + k);
 394                   }
 395                }
 396                sum /= (j1 - j0 + 1) * (i1 - i0 + 1);
 397                *dst++ = sum;
 398             }
 399          }
 400       }
 401    }
 402 #endif
 403
 404
 405    /*
 406     * Return output image
 407     */
 408
 409    if (packrowlength > 0) {
 410       rowlen = packrowlength;
 411    }
 412    else {
 413       rowlen = widthout;
 414    }
 415    if (sizeout >= packalignment) {
 416       rowstride = components * rowlen;
 417    }
 418    else {
 419       rowstride = packalignment / sizeout
 420          * CEILING(components * rowlen * sizeout, packalignment);
 421    }
 422
 423    switch (typeout) {
 424    case GL_UNSIGNED_BYTE:
 425       k = 0;
 426       for (i = 0; i < heightout; i++) {
 427          GLubyte *ubptr = (GLubyte *) dataout
 428             + i * rowstride
 429             + packskiprows * rowstride + packskippixels * components;
 430          for (j = 0; j < widthout * components; j++) {
 431             dummy(j, k + i);
 432             *ubptr++ = (GLubyte) tempout[k++];
 433          }
 434       }
 435       break;
 436    case GL_BYTE:
 437       k = 0;
 438       for (i = 0; i < heightout; i++) {
 439          GLbyte *bptr = (GLbyte *) dataout
 440             + i * rowstride
 441             + packskiprows * rowstride + packskippixels * components;
 442          for (j = 0; j < widthout * components; j++) {
 443             dummy(j, k + i);
 444             *bptr++ = (GLbyte) tempout[k++];
 445          }
 446       }
 447       break;
 448    case GL_UNSIGNED_SHORT:
 449       k = 0;
 450       for (i = 0; i < heightout; i++) {
 451          GLushort *usptr = (GLushort *) dataout
 452             + i * rowstride
 453             + packskiprows * rowstride + packskippixels * components;
 454          for (j = 0; j < widthout * components; j++) {
 455             dummy(j, k + i);
 456             *usptr++ = (GLushort) tempout[k++];
 457          }
 458       }
 459       break;
 460    case GL_SHORT:
 461       k = 0;
 462       for (i = 0; i < heightout; i++) {
 463          GLshort *sptr = (GLshort *) dataout
 464             + i * rowstride
 465             + packskiprows * rowstride + packskippixels * components;
 466          for (j = 0; j < widthout * components; j++) {
 467             dummy(j, k + i);
 468             *sptr++ = (GLshort) tempout[k++];
 469          }
 470       }
 471       break;
 472    case GL_UNSIGNED_INT:
 473       k = 0;
 474       for (i = 0; i < heightout; i++) {
 475          GLuint *uiptr = (GLuint *) dataout
 476             + i * rowstride
 477             + packskiprows * rowstride + packskippixels * components;
 478          for (j = 0; j < widthout * components; j++) {
 479             dummy(j, k + i);
 480             *uiptr++ = (GLuint) tempout[k++];
 481          }
 482       }
 483       break;
 484    case GL_INT:
 485       k = 0;
 486       for (i = 0; i < heightout; i++) {
 487          GLint *iptr = (GLint *) dataout
 488             + i * rowstride
 489             + packskiprows * rowstride + packskippixels * components;
 490          for (j = 0; j < widthout * components; j++) {
 491             dummy(j, k + i);
 492             *iptr++ = (GLint) tempout[k++];
 493          }
 494       }
 495       break;
 496    case GL_FLOAT:
 497       k = 0;
 498       for (i = 0; i < heightout; i++) {
 499          GLfloat *fptr = (GLfloat *) dataout
 500             + i * rowstride
 501             + packskiprows * rowstride + packskippixels * components;
 502          for (j = 0; j < widthout * components; j++) {
 503             dummy(j, k + i);
 504             *fptr++ = tempout[k++];
 505          }
 506       }
 507       break;
 508    default:
 509       return GLU_INVALID_ENUM;
 510    }
 511
 512
 513    /* free temporary image storage */
 514    free(tempin);
 515    free(tempout);
 516
 517    return 0;
 518 }
 519
 520
 521
 522 /*
 523  * Return the largest k such that 2^k <= n.
 524  */
 525 static GLint
 526 ilog2(GLint n)
 527 {
 528    GLint k;
 529
 530    if (n <= 0)
 531       return 0;
 532    for (k = 0; n >>= 1; k++);
 533    return k;
 534 }
 535
 536
 537
 538 /*
 539  * Find the value nearest to n which is also a power of two.
 540  */
 541 static GLint
 542 round2(GLint n)
 543 {
 544    GLint m;
 545
 546    for (m = 1; m < n; m *= 2);
 547
 548    /* m>=n */
 549    if (m - n <= n - m / 2) {
 550       return m;
 551    }
 552    else {
 553       return m / 2;
 554    }
 555 }
 556
 557
 558 /*
 559  * Given an pixel format and datatype, return the number of bytes to
 560  * store one pixel.
 561  */
 562 static GLint
 563 bytes_per_pixel(GLenum format, GLenum type)
 564 {
 565    GLint n, m;
 566
 567    switch (format) {
 568    case GL_COLOR_INDEX:
 569    case GL_STENCIL_INDEX:
 570    case GL_DEPTH_COMPONENT:
 571    case GL_RED:
 572    case GL_GREEN:
 573    case GL_BLUE:
 574    case GL_ALPHA:
 575    case GL_LUMINANCE:
 576       n = 1;
 577       break;
 578    case GL_LUMINANCE_ALPHA:
 579       n = 2;
 580       break;
 581    case GL_RGB:
 582    case GL_BGR:
 583       n = 3;
 584       break;
 585    case GL_RGBA:
 586    case GL_BGRA:
 587 #ifdef GL_EXT_abgr
 588    case GL_ABGR_EXT:
 589 #endif
 590       n = 4;
 591       break;
 592    default:
 593       n = 0;
 594    }
 595
 596    switch (type) {
 597    case GL_UNSIGNED_BYTE:
 598       m = sizeof(GLubyte);
 599       break;
 600    case GL_BYTE:
 601       m = sizeof(GLbyte);
 602       break;
 603    case GL_BITMAP:
 604       m = 1;
 605       break;
 606    case GL_UNSIGNED_SHORT:
 607       m = sizeof(GLushort);
 608       break;
 609    case GL_SHORT:
 610       m = sizeof(GLshort);
 611       break;
 612    case GL_UNSIGNED_INT:
 613       m = sizeof(GLuint);
 614       break;
 615    case GL_INT:
 616       m = sizeof(GLint);
 617       break;
 618    case GL_FLOAT:
 619       m = sizeof(GLfloat);
 620       break;
 621    default:
 622       m = 0;
 623    }
 624
 625    return n * m;
 626 }
 627
 628
 629
 630 /*
 631  * WARNING: This function isn't finished and has never been tested!!!!
 632  */
 633 GLint GLAPIENTRY
 634 gluBuild1DMipmaps(GLenum target, GLint components,
 635                   GLsizei width, GLenum format, GLenum type, const void *data)
 636 {
 637    GLubyte *texture;
 638    GLint levels, max_levels;
 639    GLint new_width, max_width;
 640    GLint i, j, k, l;
 641
 642    if (width < 1)
 643       return GLU_INVALID_VALUE;
 644
 645    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_width);
 646    max_levels = ilog2(max_width) + 1;
 647
 648    /* Compute how many mipmap images to make */
 649    levels = ilog2(width) + 1;
 650    if (levels > max_levels) {
 651       levels = max_levels;
 652    }
 653
 654    new_width = 1 << (levels - 1);
 655
 656    texture = (GLubyte *) malloc(new_width * components);
 657    if (!texture) {
 658       return GLU_OUT_OF_MEMORY;
 659    }
 660
 661    if (width != new_width) {
 662       /* initial rescaling */
 663       switch (type) {
 664       case GL_UNSIGNED_BYTE:
 665          {
 666             GLubyte *ub_data = (GLubyte *) data;
 667             for (i = 0; i < new_width; i++) {
 668                j = i * width / new_width;
 669                for (k = 0; k < components; k++) {
 670                   texture[i * components + k] = ub_data[j * components + k];
 671                }
 672             }
 673          }
 674          break;
 675       default:
 676          /* Not implemented */
 677          free(texture);
 678          return GLU_ERROR;
 679       }
 680    }
 681
 682    /* generate and load mipmap images */
 683    for (l = 0; l < levels; l++) {
 684       glTexImage1D(GL_TEXTURE_1D, l, components, new_width, 0,
 685                    format, GL_UNSIGNED_BYTE, texture);
 686
 687       /* Scale image down to 1/2 size */
 688       new_width = new_width / 2;
 689       for (i = 0; i < new_width; i++) {
 690          for (k = 0; k < components; k++) {
 691             GLint sample1, sample2;
 692             sample1 = (GLint) texture[i * 2 * components + k];
 693             sample2 = (GLint) texture[(i * 2 + 1) * components + k];
 694             texture[i * components + k] = (GLubyte) ((sample1 + sample2) / 2);
 695          }
 696       }
 697    }
 698
 699    free(texture);
 700
 701    return 0;
 702 }
 703
 704
 705
 706 GLint GLAPIENTRY
 707 gluBuild2DMipmaps(GLenum target, GLint components,
 708                   GLsizei width, GLsizei height, GLenum format,
 709                   GLenum type, const void *data)
 710 {
 711    GLint w, h, maxsize;
 712    void *image, *newimage;
 713    GLint neww, newh, level, bpp;
 714    int error;
 715    GLboolean done;
 716    GLint retval = 0;
 717    GLint unpackrowlength, unpackalignment, unpackskiprows, unpackskippixels;
 718    GLint packrowlength, packalignment, packskiprows, packskippixels;
 719
 720    if (width < 1 || height < 1)
 721       return GLU_INVALID_VALUE;
 722
 723    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxsize);
 724
 725    w = round2(width);
 726    if (w > maxsize) {
 727       w = maxsize;
 728    }
 729    h = round2(height);
 730    if (h > maxsize) {
 731       h = maxsize;
 732    }
 733
 734    bpp = bytes_per_pixel(format, type);
 735    if (bpp == 0) {
 736       /* probably a bad format or type enum */
 737       return GLU_INVALID_ENUM;
 738    }
 739
 740    /* Get current glPixelStore values */
 741    glGetIntegerv(GL_UNPACK_ROW_LENGTH, &unpackrowlength);
 742    glGetIntegerv(GL_UNPACK_ALIGNMENT, &unpackalignment);
 743    glGetIntegerv(GL_UNPACK_SKIP_ROWS, &unpackskiprows);
 744    glGetIntegerv(GL_UNPACK_SKIP_PIXELS, &unpackskippixels);
 745    glGetIntegerv(GL_PACK_ROW_LENGTH, &packrowlength);
 746    glGetIntegerv(GL_PACK_ALIGNMENT, &packalignment);
 747    glGetIntegerv(GL_PACK_SKIP_ROWS, &packskiprows);
 748    glGetIntegerv(GL_PACK_SKIP_PIXELS, &packskippixels);
 749
 750    /* set pixel packing */
 751    glPixelStorei(GL_PACK_ROW_LENGTH, 0);
 752    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 753    glPixelStorei(GL_PACK_SKIP_ROWS, 0);
 754    glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
 755
 756    done = GL_FALSE;
 757
 758    if (w != width || h != height) {
 759       /* must rescale image to get "top" mipmap texture image */
 760       image = malloc((w + 4) * h * bpp);
 761       if (!image) {
 762          return GLU_OUT_OF_MEMORY;
 763       }
 764       error = gluScaleImage(format, width, height, type, data,
 765                             w, h, type, image);
 766       if (error) {
 767          retval = error;
 768          done = GL_TRUE;
 769       }
 770    }
 771    else {
 772       image = (void *) data;
 773    }
 774
 775    level = 0;
 776    while (!done) {
 777       if (image != data) {
 778          /* set pixel unpacking */
 779          glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
 780          glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 781          glPixelStorei(GL_UNPACK_SKIP_ROWS, 0);
 782          glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
 783       }
 784
 785       glTexImage2D(target, level, components, w, h, 0, format, type, image);
 786
 787       if (w == 1 && h == 1)
 788          break;
 789
 790       neww = (w < 2) ? 1 : w / 2;
 791       newh = (h < 2) ? 1 : h / 2;
 792       newimage = malloc((neww + 4) * newh * bpp);
 793       if (!newimage) {
 794          return GLU_OUT_OF_MEMORY;
 795       }
 796
 797       error = gluScaleImage(format, w, h, type, image,
 798                             neww, newh, type, newimage);
 799       if (error) {
 800          retval = error;
 801          done = GL_TRUE;
 802       }
 803
 804       if (image != data) {
 805          free(image);
 806       }
 807       image = newimage;
 808
 809       w = neww;
 810       h = newh;
 811       level++;
 812    }
 813
 814    if (image != data) {
 815       free(image);
 816    }
 817
 818    /* Restore original glPixelStore state */
 819    glPixelStorei(GL_UNPACK_ROW_LENGTH, unpackrowlength);
 820    glPixelStorei(GL_UNPACK_ALIGNMENT, unpackalignment);
 821    glPixelStorei(GL_UNPACK_SKIP_ROWS, unpackskiprows);
 822    glPixelStorei(GL_UNPACK_SKIP_PIXELS, unpackskippixels);
 823    glPixelStorei(GL_PACK_ROW_LENGTH, packrowlength);
 824    glPixelStorei(GL_PACK_ALIGNMENT, packalignment);
 825    glPixelStorei(GL_PACK_SKIP_ROWS, packskiprows);
 826    glPixelStorei(GL_PACK_SKIP_PIXELS, packskippixels);
 827
 828    return retval;
 829 }