src/mesa/main/texcompress.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5.1
   4  *
   5  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   6  * Copyright (c) 2008 VMware, Inc.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or 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 included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26
  27 /**
  28  * \file texcompress.c
  29  * Helper functions for texture compression.
  30  */
  31
  32
  33 #include "glheader.h"
  34 #include "imports.h"
  35 #include "colormac.h"
  36 #include "formats.h"
  37 #include "mfeatures.h"
  38 #include "mtypes.h"
  39 #include "texcompress.h"
  40 #include "texcompress_fxt1.h"
  41 #include "texcompress_rgtc.h"
  42 #include "texcompress_s3tc.h"
  43 #include "swrast/s_context.h"
  44
  45
  46 /**
  47  * Get the GL base format of a specified GL compressed texture format
  48  *
  49  * From page 232 of the OpenGL 3.3 (Compatiblity Profile) spec:
  50  *
  51  *     "Compressed Internal Format      Base Internal Format    Type
  52  *     ---------------------------     --------------------    ---------
  53  *     COMPRESSED_ALPHA                ALPHA                   Generic
  54  *     COMPRESSED_LUMINANCE            LUMINANCE               Generic
  55  *     COMPRESSED_LUMINANCE_ALPHA      LUMINANCE_ALPHA         Generic
  56  *     COMPRESSED_INTENSITY            INTENSITY               Generic
  57  *     COMPRESSED_RED                  RED                     Generic
  58  *     COMPRESSED_RG                   RG                      Generic
  59  *     COMPRESSED_RGB                  RGB                     Generic
  60  *     COMPRESSED_RGBA                 RGBA                    Generic
  61  *     COMPRESSED_SRGB                 RGB                     Generic
  62  *     COMPRESSED_SRGB_ALPHA           RGBA                    Generic
  63  *     COMPRESSED_SLUMINANCE           LUMINANCE               Generic
  64  *     COMPRESSED_SLUMINANCE_ALPHA     LUMINANCE_ALPHA         Generic
  65  *     COMPRESSED_RED_RGTC1            RED                     Specific
  66  *     COMPRESSED_SIGNED_RED_RGTC1     RED                     Specific
  67  *     COMPRESSED_RG_RGTC2             RG                      Specific
  68  *     COMPRESSED_SIGNED_RG_RGTC2      RG                      Specific"
  69  *
  70  * \return
  71  * The base format of \c format if \c format is a compressed format (either
  72  * generic or specific.  Otherwise 0 is returned.
  73  */
  74 GLenum
  75 _mesa_gl_compressed_format_base_format(GLenum format)
  76 {
  77    switch (format) {
  78    case GL_COMPRESSED_RED:
  79    case GL_COMPRESSED_RED_RGTC1:
  80    case GL_COMPRESSED_SIGNED_RED_RGTC1:
  81       return GL_RED;
  82
  83    case GL_COMPRESSED_RG:
  84    case GL_COMPRESSED_RG_RGTC2:
  85    case GL_COMPRESSED_SIGNED_RG_RGTC2:
  86       return GL_RG;
  87
  88    case GL_COMPRESSED_RGB:
  89    case GL_COMPRESSED_SRGB:
  90    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
  91    case GL_COMPRESSED_RGB_FXT1_3DFX:
  92    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
  93       return GL_RGB;
  94
  95    case GL_COMPRESSED_RGBA:
  96    case GL_COMPRESSED_SRGB_ALPHA:
  97    case GL_COMPRESSED_RGBA_BPTC_UNORM_ARB:
  98    case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM_ARB:
  99    case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT_ARB:
 100    case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_ARB:
 101    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 102    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 103    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 104    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 105    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 106    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 107    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 108       return GL_RGBA;
 109
 110    case GL_COMPRESSED_ALPHA:
 111       return GL_ALPHA;
 112
 113    case GL_COMPRESSED_LUMINANCE:
 114    case GL_COMPRESSED_SLUMINANCE:
 115    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 116    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 117       return GL_LUMINANCE;
 118
 119    case GL_COMPRESSED_LUMINANCE_ALPHA:
 120    case GL_COMPRESSED_SLUMINANCE_ALPHA:
 121    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 122    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 123    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 124       return GL_LUMINANCE_ALPHA;
 125
 126    case GL_COMPRESSED_INTENSITY:
 127       return GL_INTENSITY;
 128
 129    default:
 130       return 0;
 131    }
 132 }
 133
 134 /**
 135  * Return list of (and count of) all specific texture compression
 136  * formats that are supported.
 137  *
 138  * Some formats are \b not returned by this function.  The
 139  * \c GL_COMPRESSED_TEXTURE_FORMATS query only returns formats that are
 140  * "suitable for general-purpose usage."  All texture compression extensions
 141  * have taken this to mean either linear RGB or linear RGBA.
 142  *
 143  * The GL_ARB_texture_compress_rgtc spec says:
 144  *
 145  *    "19) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 146  *        GL_COMPRESSED_TEXTURE_FORMATS queries return the RGTC formats?
 147  *
 148  *        RESOLVED:  No.
 149  *
 150  *        The OpenGL 2.1 specification says "The only values returned
 151  *        by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those
 152  *        corresponding to formats suitable for general-purpose usage.
 153  *        The renderer will not enumerate formats with restrictions that
 154  *        need to be specifically understood prior to use."
 155  *
 156  *        Compressed textures with just red or red-green components are
 157  *        not general-purpose so should not be returned by these queries
 158  *        because they have restrictions.
 159  *
 160  *        Applications that seek to use the RGTC formats should do so
 161  *        by looking for this extension's name in the string returned by
 162  *        glGetString(GL_EXTENSIONS) rather than
 163  *        what GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 164  *        GL_COMPRESSED_TEXTURE_FORMATS return."
 165  *
 166  * There is nearly identical wording in the GL_EXT_texture_compression_rgtc
 167  * spec.
 168  *
 169  * The GL_EXT_texture_rRGB spec says:
 170  *
 171  *    "22) Should the new COMPRESSED_SRGB_* formats be listed in an
 172  *        implementation's GL_COMPRESSED_TEXTURE_FORMATS list?
 173  *
 174  *        RESOLVED:  No.  Section 3.8.1 says formats listed by
 175  *        GL_COMPRESSED_TEXTURE_FORMATS are "suitable for general-purpose
 176  *        usage."  The non-linear distribution of red, green, and
 177  *        blue for these sRGB compressed formats makes them not really
 178  *        general-purpose."
 179  *
 180  * The GL_EXT_texture_compression_latc spec says:
 181  *
 182  *    "16) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 183  *        GL_COMPRESSED_TEXTURE_FORMATS queries return the LATC formats?
 184  *
 185  *        RESOLVED:  No.
 186  *
 187  *        The OpenGL 2.1 specification says "The only values returned
 188  *        by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those
 189  *        corresponding to formats suitable for general-purpose usage.
 190  *        The renderer will not enumerate formats with restrictions that
 191  *        need to be specifically understood prior to use."
 192  *
 193  *        Historically, OpenGL implementation have advertised the RGB and
 194  *        RGBA versions of the S3TC extensions compressed format tokens
 195  *        through this mechanism.
 196  *
 197  *        The specification is not sufficiently clear about what "suitable
 198  *        for general-purpose usage" means.  Historically that seems to mean
 199  *        unsigned RGB or unsigned RGBA.  The DXT1 format supporting alpha
 200  *        (GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) is not exposed in the list (at
 201  *        least for NVIDIA drivers) because the alpha is always 1.0 expect
 202  *        when it is 0.0 when RGB is required to be black.  NVIDIA's even
 203  *        limits itself to true linear RGB or RGBA formats, specifically
 204  *        not including EXT_texture_sRGB's sRGB S3TC compressed formats.
 205  *
 206  *        Adding luminance and luminance-alpha texture formats (and
 207  *        certainly signed versions of luminance and luminance-alpha
 208  *        formats!) invites potential comptaibility problems with old
 209  *        applications using this mechanism since old applications are
 210  *        unlikely to expect non-RGB or non-RGBA formats to be advertised
 211  *        through this mechanism.  However no specific misinteractions
 212  *        with old applications is known.
 213  *
 214  *        Applications that seek to use the LATC formats should do so
 215  *        by looking for this extension's name in the string returned by
 216  *        glGetString(GL_EXTENSIONS) rather than
 217  *        what GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 218  *        GL_COMPRESSED_TEXTURE_FORMATS return."
 219  *
 220  * There is no formal spec for GL_ATI_texture_compression_3dc.  Since the
 221  * formats added by this extension are luminance-alpha formats, it is
 222  * reasonable to expect them to follow the same rules as
 223  * GL_EXT_texture_compression_latc.  At the very least, Catalyst 11.6 does not
 224  * expose the 3dc formats through this mechanism.
 225  *
 226  * \param ctx  the GL context
 227  * \param formats  the resulting format list (may be NULL).
 228  *
 229  * \return number of formats.
 230  */
 231 GLuint
 232 _mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats)
 233 {
 234    GLuint n = 0;
 235    if (ctx->Extensions.TDFX_texture_compression_FXT1) {
 236       if (formats) {
 237          formats[n++] = GL_COMPRESSED_RGB_FXT1_3DFX;
 238          formats[n++] = GL_COMPRESSED_RGBA_FXT1_3DFX;
 239       }
 240       else {
 241          n += 2;
 242       }
 243    }
 244
 245    if (ctx->Extensions.EXT_texture_compression_s3tc) {
 246       if (formats) {
 247          formats[n++] = GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 248          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 249          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 250       }
 251       else {
 252          n += 3;
 253       }
 254    }
 255    if (ctx->Extensions.S3_s3tc) {
 256       if (formats) {
 257          formats[n++] = GL_RGB_S3TC;
 258          formats[n++] = GL_RGB4_S3TC;
 259          formats[n++] = GL_RGBA_S3TC;
 260          formats[n++] = GL_RGBA4_S3TC;
 261       }
 262       else {
 263          n += 4;
 264       }
 265    }
 266
 267 #if FEATURE_ES1 || FEATURE_ES2
 268    if (formats) {
 269       formats[n++] = GL_PALETTE4_RGB8_OES;
 270       formats[n++] = GL_PALETTE4_RGBA8_OES;
 271       formats[n++] = GL_PALETTE4_R5_G6_B5_OES;
 272       formats[n++] = GL_PALETTE4_RGBA4_OES;
 273       formats[n++] = GL_PALETTE4_RGB5_A1_OES;
 274       formats[n++] = GL_PALETTE8_RGB8_OES;
 275       formats[n++] = GL_PALETTE8_RGBA8_OES;
 276       formats[n++] = GL_PALETTE8_R5_G6_B5_OES;
 277       formats[n++] = GL_PALETTE8_RGBA4_OES;
 278       formats[n++] = GL_PALETTE8_RGB5_A1_OES;
 279    }
 280    else {
 281       n += 10;
 282    }
 283 #endif
 284
 285    return n;
 286 }
 287
 288
 289 /**
 290  * Convert a compressed MESA_FORMAT_x to a GLenum.
 291  */
 292 gl_format
 293 _mesa_glenum_to_compressed_format(GLenum format)
 294 {
 295    switch (format) {
 296    case GL_COMPRESSED_RGB_FXT1_3DFX:
 297       return MESA_FORMAT_RGB_FXT1;
 298    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 299       return MESA_FORMAT_RGBA_FXT1;
 300
 301    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
 302    case GL_RGB_S3TC:
 303       return MESA_FORMAT_RGB_DXT1;
 304    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 305    case GL_RGB4_S3TC:
 306       return MESA_FORMAT_RGBA_DXT1;
 307    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 308    case GL_RGBA_S3TC:
 309       return MESA_FORMAT_RGBA_DXT3;
 310    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 311    case GL_RGBA4_S3TC:
 312       return MESA_FORMAT_RGBA_DXT5;
 313
 314    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
 315       return MESA_FORMAT_SRGB_DXT1;
 316    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 317       return MESA_FORMAT_SRGBA_DXT1;
 318    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 319       return MESA_FORMAT_SRGBA_DXT3;
 320    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 321       return MESA_FORMAT_SRGBA_DXT5;
 322
 323    case GL_COMPRESSED_RED_RGTC1:
 324       return MESA_FORMAT_RED_RGTC1;
 325    case GL_COMPRESSED_SIGNED_RED_RGTC1:
 326       return MESA_FORMAT_SIGNED_RED_RGTC1;
 327    case GL_COMPRESSED_RG_RGTC2:
 328       return MESA_FORMAT_RG_RGTC2;
 329    case GL_COMPRESSED_SIGNED_RG_RGTC2:
 330       return MESA_FORMAT_SIGNED_RG_RGTC2;
 331
 332    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 333       return MESA_FORMAT_L_LATC1;
 334    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 335       return MESA_FORMAT_SIGNED_L_LATC1;
 336    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 337    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 338       return MESA_FORMAT_LA_LATC2;
 339    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 340       return MESA_FORMAT_SIGNED_LA_LATC2;
 341
 342    default:
 343       return MESA_FORMAT_NONE;
 344    }
 345 }
 346
 347
 348 /**
 349  * Given a compressed MESA_FORMAT_x value, return the corresponding
 350  * GLenum for that format.
 351  * This is needed for glGetTexLevelParameter(GL_TEXTURE_INTERNAL_FORMAT)
 352  * which must return the specific texture format used when the user might
 353  * have originally specified a generic compressed format in their
 354  * glTexImage2D() call.
 355  * For non-compressed textures, we always return the user-specified
 356  * internal format unchanged.
 357  */
 358 GLenum
 359 _mesa_compressed_format_to_glenum(struct gl_context *ctx, GLuint mesaFormat)
 360 {
 361    switch (mesaFormat) {
 362 #if FEATURE_texture_fxt1
 363    case MESA_FORMAT_RGB_FXT1:
 364       return GL_COMPRESSED_RGB_FXT1_3DFX;
 365    case MESA_FORMAT_RGBA_FXT1:
 366       return GL_COMPRESSED_RGBA_FXT1_3DFX;
 367 #endif
 368 #if FEATURE_texture_s3tc
 369    case MESA_FORMAT_RGB_DXT1:
 370       return GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 371    case MESA_FORMAT_RGBA_DXT1:
 372       return GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 373    case MESA_FORMAT_RGBA_DXT3:
 374       return GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 375    case MESA_FORMAT_RGBA_DXT5:
 376       return GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 377 #if FEATURE_EXT_texture_sRGB
 378    case MESA_FORMAT_SRGB_DXT1:
 379       return GL_COMPRESSED_SRGB_S3TC_DXT1_EXT;
 380    case MESA_FORMAT_SRGBA_DXT1:
 381       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT;
 382    case MESA_FORMAT_SRGBA_DXT3:
 383       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT;
 384    case MESA_FORMAT_SRGBA_DXT5:
 385       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT;
 386 #endif
 387 #endif
 388
 389    case MESA_FORMAT_RED_RGTC1:
 390       return GL_COMPRESSED_RED_RGTC1;
 391    case MESA_FORMAT_SIGNED_RED_RGTC1:
 392       return GL_COMPRESSED_SIGNED_RED_RGTC1;
 393    case MESA_FORMAT_RG_RGTC2:
 394       return GL_COMPRESSED_RG_RGTC2;
 395    case MESA_FORMAT_SIGNED_RG_RGTC2:
 396       return GL_COMPRESSED_SIGNED_RG_RGTC2;
 397
 398    case MESA_FORMAT_L_LATC1:
 399       return GL_COMPRESSED_LUMINANCE_LATC1_EXT;
 400    case MESA_FORMAT_SIGNED_L_LATC1:
 401       return GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT;
 402    case MESA_FORMAT_LA_LATC2:
 403       return GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT;
 404    case MESA_FORMAT_SIGNED_LA_LATC2:
 405       return GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT;
 406
 407    default:
 408       _mesa_problem(ctx, "Unexpected mesa texture format in"
 409                     " _mesa_compressed_format_to_glenum()");
 410       return 0;
 411    }
 412 }
 413
 414
 415 /*
 416  * Return the address of the pixel at (col, row, img) in a
 417  * compressed texture image.
 418  * \param col, row, img - image position (3D), should be a multiple of the
 419  *                        format's block size.
 420  * \param format - compressed image format
 421  * \param width - image width (stride) in pixels
 422  * \param image - the image address
 423  * \return address of pixel at (row, col, img)
 424  */
 425 GLubyte *
 426 _mesa_compressed_image_address(GLint col, GLint row, GLint img,
 427                                gl_format mesaFormat,
 428                                GLsizei width, const GLubyte *image)
 429 {
 430    /* XXX only 2D images implemented, not 3D */
 431    const GLuint blockSize = _mesa_get_format_bytes(mesaFormat);
 432    GLuint bw, bh;
 433    GLint offset;
 434
 435    _mesa_get_format_block_size(mesaFormat, &bw, &bh);
 436
 437    ASSERT(col % bw == 0);
 438    ASSERT(row % bh == 0);
 439
 440    offset = ((width + bw - 1) / bw) * (row / bh) + col / bw;
 441    offset *= blockSize;
 442
 443    return (GLubyte *) image + offset;
 444 }
 445
 446
 447 /**
 448  * Decompress a compressed texture image, returning a GL_RGBA/GL_FLOAT image.
 449  */
 450 void
 451 _mesa_decompress_image(gl_format format, GLuint width, GLuint height,
 452                        const GLubyte *src, GLint srcRowStride,
 453                        GLfloat *dest)
 454 {
 455    void (*fetch)(const struct swrast_texture_image *texImage,
 456                  GLint i, GLint j, GLint k, GLfloat *texel);
 457    struct swrast_texture_image texImage;  /* dummy teximage */
 458    GLuint i, j;
 459
 460    /* setup dummy texture image info */
 461    memset(&texImage, 0, sizeof(texImage));
 462    texImage.Base.Data = (void *) src;
 463    texImage.Base.RowStride = srcRowStride;
 464
 465    switch (format) {
 466    /* DXT formats */
 467    case MESA_FORMAT_RGB_DXT1:
 468       fetch = _mesa_fetch_texel_2d_f_rgb_dxt1;
 469       break;
 470    case MESA_FORMAT_RGBA_DXT1:
 471       fetch = _mesa_fetch_texel_2d_f_rgba_dxt1;
 472       break;
 473    case MESA_FORMAT_RGBA_DXT3:
 474       fetch = _mesa_fetch_texel_2d_f_rgba_dxt3;
 475       break;
 476    case MESA_FORMAT_RGBA_DXT5:
 477       fetch = _mesa_fetch_texel_2d_f_rgba_dxt5;
 478       break;
 479
 480    /* FXT1 formats */
 481    case MESA_FORMAT_RGB_FXT1:
 482       fetch = _mesa_fetch_texel_2d_f_rgb_fxt1;
 483       break;
 484    case MESA_FORMAT_RGBA_FXT1:
 485       fetch = _mesa_fetch_texel_2d_f_rgba_fxt1;
 486       break;
 487
 488    /* Red/RG formats */
 489    case MESA_FORMAT_RED_RGTC1:
 490       fetch = _mesa_fetch_texel_2d_f_red_rgtc1;
 491       break;
 492    case MESA_FORMAT_SIGNED_RED_RGTC1:
 493       fetch = _mesa_fetch_texel_2d_f_signed_red_rgtc1;
 494       break;
 495    case MESA_FORMAT_RG_RGTC2:
 496       fetch = _mesa_fetch_texel_2d_f_rg_rgtc2;
 497       break;
 498    case MESA_FORMAT_SIGNED_RG_RGTC2:
 499       fetch = _mesa_fetch_texel_2d_f_signed_rg_rgtc2;
 500       break;
 501
 502    /* L/LA formats */
 503    case MESA_FORMAT_L_LATC1:
 504       fetch = _mesa_fetch_texel_2d_f_l_latc1;
 505       break;
 506    case MESA_FORMAT_SIGNED_L_LATC1:
 507       fetch = _mesa_fetch_texel_2d_f_signed_l_latc1;
 508       break;
 509    case MESA_FORMAT_LA_LATC2:
 510       fetch = _mesa_fetch_texel_2d_f_la_latc2;
 511       break;
 512    case MESA_FORMAT_SIGNED_LA_LATC2:
 513       fetch = _mesa_fetch_texel_2d_f_signed_la_latc2;
 514       break;
 515
 516    default:
 517       _mesa_problem(NULL, "Unexpected format in _mesa_decompress_image()");
 518       return;
 519    }
 520
 521    for (j = 0; j < height; j++) {
 522       for (i = 0; i < width; i++) {
 523          fetch(&texImage, i, j, 0, dest);
 524          dest += 4;
 525       }
 526    }
 527 }