src/mesa/main/texcompress.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   5  * Copyright (c) 2008 VMware, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * 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 "context.h"
  37 #include "formats.h"
  38 #include "mtypes.h"
  39 #include "context.h"
  40 #include "texcompress.h"
  41 #include "texcompress_fxt1.h"
  42 #include "texcompress_rgtc.h"
  43 #include "texcompress_s3tc.h"
  44 #include "texcompress_etc.h"
  45
  46
  47 /**
  48  * Get the GL base format of a specified GL compressed texture format
  49  *
  50  * From page 232 of the OpenGL 3.3 (Compatiblity Profile) spec:
  51  *
  52  *     "Compressed Internal Format      Base Internal Format    Type
  53  *     ---------------------------     --------------------    ---------
  54  *     COMPRESSED_ALPHA                ALPHA                   Generic
  55  *     COMPRESSED_LUMINANCE            LUMINANCE               Generic
  56  *     COMPRESSED_LUMINANCE_ALPHA      LUMINANCE_ALPHA         Generic
  57  *     COMPRESSED_INTENSITY            INTENSITY               Generic
  58  *     COMPRESSED_RED                  RED                     Generic
  59  *     COMPRESSED_RG                   RG                      Generic
  60  *     COMPRESSED_RGB                  RGB                     Generic
  61  *     COMPRESSED_RGBA                 RGBA                    Generic
  62  *     COMPRESSED_SRGB                 RGB                     Generic
  63  *     COMPRESSED_SRGB_ALPHA           RGBA                    Generic
  64  *     COMPRESSED_SLUMINANCE           LUMINANCE               Generic
  65  *     COMPRESSED_SLUMINANCE_ALPHA     LUMINANCE_ALPHA         Generic
  66  *     COMPRESSED_RED_RGTC1            RED                     Specific
  67  *     COMPRESSED_SIGNED_RED_RGTC1     RED                     Specific
  68  *     COMPRESSED_RG_RGTC2             RG                      Specific
  69  *     COMPRESSED_SIGNED_RG_RGTC2      RG                      Specific"
  70  *
  71  * \return
  72  * The base format of \c format if \c format is a compressed format (either
  73  * generic or specific.  Otherwise 0 is returned.
  74  */
  75 GLenum
  76 _mesa_gl_compressed_format_base_format(GLenum format)
  77 {
  78    switch (format) {
  79    case GL_COMPRESSED_RED:
  80    case GL_COMPRESSED_R11_EAC:
  81    case GL_COMPRESSED_RED_RGTC1:
  82    case GL_COMPRESSED_SIGNED_R11_EAC:
  83    case GL_COMPRESSED_SIGNED_RED_RGTC1:
  84       return GL_RED;
  85
  86    case GL_COMPRESSED_RG:
  87    case GL_COMPRESSED_RG11_EAC:
  88    case GL_COMPRESSED_RG_RGTC2:
  89    case GL_COMPRESSED_SIGNED_RG11_EAC:
  90    case GL_COMPRESSED_SIGNED_RG_RGTC2:
  91       return GL_RG;
  92
  93    case GL_COMPRESSED_RGB:
  94    case GL_COMPRESSED_SRGB:
  95    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
  96    case GL_COMPRESSED_RGB_FXT1_3DFX:
  97    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
  98    case GL_ETC1_RGB8_OES:
  99    case GL_COMPRESSED_RGB8_ETC2:
 100    case GL_COMPRESSED_SRGB8_ETC2:
 101       return GL_RGB;
 102
 103    case GL_COMPRESSED_RGBA:
 104    case GL_COMPRESSED_SRGB_ALPHA:
 105    case GL_COMPRESSED_RGBA_BPTC_UNORM_ARB:
 106    case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM_ARB:
 107    case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT_ARB:
 108    case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_ARB:
 109    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 110    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 111    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 112    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 113    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 114    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 115    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 116    case GL_COMPRESSED_RGBA8_ETC2_EAC:
 117    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
 118    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 119    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 120       return GL_RGBA;
 121
 122    case GL_COMPRESSED_ALPHA:
 123       return GL_ALPHA;
 124
 125    case GL_COMPRESSED_LUMINANCE:
 126    case GL_COMPRESSED_SLUMINANCE:
 127    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 128    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 129       return GL_LUMINANCE;
 130
 131    case GL_COMPRESSED_LUMINANCE_ALPHA:
 132    case GL_COMPRESSED_SLUMINANCE_ALPHA:
 133    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 134    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 135    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 136       return GL_LUMINANCE_ALPHA;
 137
 138    case GL_COMPRESSED_INTENSITY:
 139       return GL_INTENSITY;
 140
 141    default:
 142       return 0;
 143    }
 144 }
 145
 146 /**
 147  * Return list of (and count of) all specific texture compression
 148  * formats that are supported.
 149  *
 150  * Some formats are \b not returned by this function.  The
 151  * \c GL_COMPRESSED_TEXTURE_FORMATS query only returns formats that are
 152  * "suitable for general-purpose usage."  All texture compression extensions
 153  * have taken this to mean either linear RGB or linear RGBA.
 154  *
 155  * The GL_ARB_texture_compress_rgtc spec says:
 156  *
 157  *    "19) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 158  *        GL_COMPRESSED_TEXTURE_FORMATS queries return the RGTC formats?
 159  *
 160  *        RESOLVED:  No.
 161  *
 162  *        The OpenGL 2.1 specification says "The only values returned
 163  *        by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those
 164  *        corresponding to formats suitable for general-purpose usage.
 165  *        The renderer will not enumerate formats with restrictions that
 166  *        need to be specifically understood prior to use."
 167  *
 168  *        Compressed textures with just red or red-green components are
 169  *        not general-purpose so should not be returned by these queries
 170  *        because they have restrictions.
 171  *
 172  *        Applications that seek to use the RGTC formats should do so
 173  *        by looking for this extension's name in the string returned by
 174  *        glGetString(GL_EXTENSIONS) rather than
 175  *        what GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 176  *        GL_COMPRESSED_TEXTURE_FORMATS return."
 177  *
 178  * There is nearly identical wording in the GL_EXT_texture_compression_rgtc
 179  * spec.
 180  *
 181  * The GL_EXT_texture_rRGB spec says:
 182  *
 183  *    "22) Should the new COMPRESSED_SRGB_* formats be listed in an
 184  *        implementation's GL_COMPRESSED_TEXTURE_FORMATS list?
 185  *
 186  *        RESOLVED:  No.  Section 3.8.1 says formats listed by
 187  *        GL_COMPRESSED_TEXTURE_FORMATS are "suitable for general-purpose
 188  *        usage."  The non-linear distribution of red, green, and
 189  *        blue for these sRGB compressed formats makes them not really
 190  *        general-purpose."
 191  *
 192  * The GL_EXT_texture_compression_latc spec says:
 193  *
 194  *    "16) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 195  *        GL_COMPRESSED_TEXTURE_FORMATS queries return the LATC formats?
 196  *
 197  *        RESOLVED:  No.
 198  *
 199  *        The OpenGL 2.1 specification says "The only values returned
 200  *        by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those
 201  *        corresponding to formats suitable for general-purpose usage.
 202  *        The renderer will not enumerate formats with restrictions that
 203  *        need to be specifically understood prior to use."
 204  *
 205  *        Historically, OpenGL implementation have advertised the RGB and
 206  *        RGBA versions of the S3TC extensions compressed format tokens
 207  *        through this mechanism.
 208  *
 209  *        The specification is not sufficiently clear about what "suitable
 210  *        for general-purpose usage" means.  Historically that seems to mean
 211  *        unsigned RGB or unsigned RGBA.  The DXT1 format supporting alpha
 212  *        (GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) is not exposed in the list (at
 213  *        least for NVIDIA drivers) because the alpha is always 1.0 expect
 214  *        when it is 0.0 when RGB is required to be black.  NVIDIA's even
 215  *        limits itself to true linear RGB or RGBA formats, specifically
 216  *        not including EXT_texture_sRGB's sRGB S3TC compressed formats.
 217  *
 218  *        Adding luminance and luminance-alpha texture formats (and
 219  *        certainly signed versions of luminance and luminance-alpha
 220  *        formats!) invites potential comptaibility problems with old
 221  *        applications using this mechanism since old applications are
 222  *        unlikely to expect non-RGB or non-RGBA formats to be advertised
 223  *        through this mechanism.  However no specific misinteractions
 224  *        with old applications is known.
 225  *
 226  *        Applications that seek to use the LATC formats should do so
 227  *        by looking for this extension's name in the string returned by
 228  *        glGetString(GL_EXTENSIONS) rather than
 229  *        what GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 230  *        GL_COMPRESSED_TEXTURE_FORMATS return."
 231  *
 232  * There is no formal spec for GL_ATI_texture_compression_3dc.  Since the
 233  * formats added by this extension are luminance-alpha formats, it is
 234  * reasonable to expect them to follow the same rules as
 235  * GL_EXT_texture_compression_latc.  At the very least, Catalyst 11.6 does not
 236  * expose the 3dc formats through this mechanism.
 237  *
 238  * \param ctx  the GL context
 239  * \param formats  the resulting format list (may be NULL).
 240  *
 241  * \return number of formats.
 242  */
 243 GLuint
 244 _mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats)
 245 {
 246    GLuint n = 0;
 247    if (ctx->Extensions.TDFX_texture_compression_FXT1) {
 248       if (formats) {
 249          formats[n++] = GL_COMPRESSED_RGB_FXT1_3DFX;
 250          formats[n++] = GL_COMPRESSED_RGBA_FXT1_3DFX;
 251       }
 252       else {
 253          n += 2;
 254       }
 255    }
 256
 257    if (ctx->Extensions.EXT_texture_compression_s3tc) {
 258       if (formats) {
 259          formats[n++] = GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 260          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 261          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 262       }
 263       else {
 264          n += 3;
 265       }
 266    }
 267
 268    /* The GL_OES_compressed_ETC1_RGB8_texture spec says:
 269     *
 270     *     "New State
 271     *
 272     *         The queries for NUM_COMPRESSED_TEXTURE_FORMATS and
 273     *         COMPRESSED_TEXTURE_FORMATS include ETC1_RGB8_OES."
 274     */
 275    if (_mesa_is_gles(ctx)
 276        && ctx->Extensions.OES_compressed_ETC1_RGB8_texture) {
 277       if (formats) {
 278          formats[n++] = GL_ETC1_RGB8_OES;
 279       }
 280       else {
 281          n += 1;
 282       }
 283    }
 284
 285    if (ctx->API == API_OPENGLES) {
 286       if (formats) {
 287          formats[n++] = GL_PALETTE4_RGB8_OES;
 288          formats[n++] = GL_PALETTE4_RGBA8_OES;
 289          formats[n++] = GL_PALETTE4_R5_G6_B5_OES;
 290          formats[n++] = GL_PALETTE4_RGBA4_OES;
 291          formats[n++] = GL_PALETTE4_RGB5_A1_OES;
 292          formats[n++] = GL_PALETTE8_RGB8_OES;
 293          formats[n++] = GL_PALETTE8_RGBA8_OES;
 294          formats[n++] = GL_PALETTE8_R5_G6_B5_OES;
 295          formats[n++] = GL_PALETTE8_RGBA4_OES;
 296          formats[n++] = GL_PALETTE8_RGB5_A1_OES;
 297       }
 298       else {
 299          n += 10;
 300       }
 301    }
 302
 303    if (_mesa_is_gles3(ctx)) {
 304       if (formats) {
 305          formats[n++] = GL_COMPRESSED_RGB8_ETC2;
 306          formats[n++] = GL_COMPRESSED_SRGB8_ETC2;
 307          formats[n++] = GL_COMPRESSED_RGBA8_ETC2_EAC;
 308          formats[n++] = GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 309          formats[n++] = GL_COMPRESSED_R11_EAC;
 310          formats[n++] = GL_COMPRESSED_RG11_EAC;
 311          formats[n++] = GL_COMPRESSED_SIGNED_R11_EAC;
 312          formats[n++] = GL_COMPRESSED_SIGNED_RG11_EAC;
 313          formats[n++] = GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 314          formats[n++] = GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 315       }
 316       else {
 317          n += 10;
 318       }
 319    }
 320    return n;
 321 }
 322
 323
 324 /**
 325  * Convert a compressed MESA_FORMAT_x to a GLenum.
 326  */
 327 gl_format
 328 _mesa_glenum_to_compressed_format(GLenum format)
 329 {
 330    switch (format) {
 331    case GL_COMPRESSED_RGB_FXT1_3DFX:
 332       return MESA_FORMAT_RGB_FXT1;
 333    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 334       return MESA_FORMAT_RGBA_FXT1;
 335
 336    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
 337    case GL_RGB_S3TC:
 338       return MESA_FORMAT_RGB_DXT1;
 339    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 340    case GL_RGB4_S3TC:
 341       return MESA_FORMAT_RGBA_DXT1;
 342    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 343    case GL_RGBA_S3TC:
 344       return MESA_FORMAT_RGBA_DXT3;
 345    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 346    case GL_RGBA4_S3TC:
 347       return MESA_FORMAT_RGBA_DXT5;
 348
 349    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
 350       return MESA_FORMAT_SRGB_DXT1;
 351    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 352       return MESA_FORMAT_SRGBA_DXT1;
 353    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 354       return MESA_FORMAT_SRGBA_DXT3;
 355    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 356       return MESA_FORMAT_SRGBA_DXT5;
 357
 358    case GL_COMPRESSED_RED_RGTC1:
 359       return MESA_FORMAT_RED_RGTC1;
 360    case GL_COMPRESSED_SIGNED_RED_RGTC1:
 361       return MESA_FORMAT_SIGNED_RED_RGTC1;
 362    case GL_COMPRESSED_RG_RGTC2:
 363       return MESA_FORMAT_RG_RGTC2;
 364    case GL_COMPRESSED_SIGNED_RG_RGTC2:
 365       return MESA_FORMAT_SIGNED_RG_RGTC2;
 366
 367    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 368       return MESA_FORMAT_L_LATC1;
 369    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 370       return MESA_FORMAT_SIGNED_L_LATC1;
 371    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 372    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 373       return MESA_FORMAT_LA_LATC2;
 374    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 375       return MESA_FORMAT_SIGNED_LA_LATC2;
 376
 377    case GL_ETC1_RGB8_OES:
 378       return MESA_FORMAT_ETC1_RGB8;
 379    case GL_COMPRESSED_RGB8_ETC2:
 380       return MESA_FORMAT_ETC2_RGB8;
 381    case GL_COMPRESSED_SRGB8_ETC2:
 382       return MESA_FORMAT_ETC2_SRGB8;
 383    case GL_COMPRESSED_RGBA8_ETC2_EAC:
 384       return MESA_FORMAT_ETC2_RGBA8_EAC;
 385    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
 386       return MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC;
 387    case GL_COMPRESSED_R11_EAC:
 388       return MESA_FORMAT_ETC2_R11_EAC;
 389    case GL_COMPRESSED_RG11_EAC:
 390       return MESA_FORMAT_ETC2_RG11_EAC;
 391    case GL_COMPRESSED_SIGNED_R11_EAC:
 392       return MESA_FORMAT_ETC2_SIGNED_R11_EAC;
 393    case GL_COMPRESSED_SIGNED_RG11_EAC:
 394       return MESA_FORMAT_ETC2_SIGNED_RG11_EAC;
 395    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 396       return MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1;
 397    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 398       return MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1;
 399
 400    default:
 401       return MESA_FORMAT_NONE;
 402    }
 403 }
 404
 405
 406 /**
 407  * Given a compressed MESA_FORMAT_x value, return the corresponding
 408  * GLenum for that format.
 409  * This is needed for glGetTexLevelParameter(GL_TEXTURE_INTERNAL_FORMAT)
 410  * which must return the specific texture format used when the user might
 411  * have originally specified a generic compressed format in their
 412  * glTexImage2D() call.
 413  * For non-compressed textures, we always return the user-specified
 414  * internal format unchanged.
 415  */
 416 GLenum
 417 _mesa_compressed_format_to_glenum(struct gl_context *ctx, gl_format mesaFormat)
 418 {
 419    switch (mesaFormat) {
 420    case MESA_FORMAT_RGB_FXT1:
 421       return GL_COMPRESSED_RGB_FXT1_3DFX;
 422    case MESA_FORMAT_RGBA_FXT1:
 423       return GL_COMPRESSED_RGBA_FXT1_3DFX;
 424    case MESA_FORMAT_RGB_DXT1:
 425       return GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 426    case MESA_FORMAT_RGBA_DXT1:
 427       return GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 428    case MESA_FORMAT_RGBA_DXT3:
 429       return GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 430    case MESA_FORMAT_RGBA_DXT5:
 431       return GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 432    case MESA_FORMAT_SRGB_DXT1:
 433       return GL_COMPRESSED_SRGB_S3TC_DXT1_EXT;
 434    case MESA_FORMAT_SRGBA_DXT1:
 435       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT;
 436    case MESA_FORMAT_SRGBA_DXT3:
 437       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT;
 438    case MESA_FORMAT_SRGBA_DXT5:
 439       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT;
 440    case MESA_FORMAT_RED_RGTC1:
 441       return GL_COMPRESSED_RED_RGTC1;
 442    case MESA_FORMAT_SIGNED_RED_RGTC1:
 443       return GL_COMPRESSED_SIGNED_RED_RGTC1;
 444    case MESA_FORMAT_RG_RGTC2:
 445       return GL_COMPRESSED_RG_RGTC2;
 446    case MESA_FORMAT_SIGNED_RG_RGTC2:
 447       return GL_COMPRESSED_SIGNED_RG_RGTC2;
 448
 449    case MESA_FORMAT_L_LATC1:
 450       return GL_COMPRESSED_LUMINANCE_LATC1_EXT;
 451    case MESA_FORMAT_SIGNED_L_LATC1:
 452       return GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT;
 453    case MESA_FORMAT_LA_LATC2:
 454       return GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT;
 455    case MESA_FORMAT_SIGNED_LA_LATC2:
 456       return GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT;
 457
 458    case MESA_FORMAT_ETC1_RGB8:
 459       return GL_ETC1_RGB8_OES;
 460    case MESA_FORMAT_ETC2_RGB8:
 461       return GL_COMPRESSED_RGB8_ETC2;
 462    case MESA_FORMAT_ETC2_SRGB8:
 463       return GL_COMPRESSED_SRGB8_ETC2;
 464    case MESA_FORMAT_ETC2_RGBA8_EAC:
 465       return GL_COMPRESSED_RGBA8_ETC2_EAC;
 466    case MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC:
 467       return GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 468    case MESA_FORMAT_ETC2_R11_EAC:
 469       return GL_COMPRESSED_R11_EAC;
 470    case MESA_FORMAT_ETC2_RG11_EAC:
 471       return GL_COMPRESSED_RG11_EAC;
 472    case MESA_FORMAT_ETC2_SIGNED_R11_EAC:
 473       return GL_COMPRESSED_SIGNED_R11_EAC;
 474    case MESA_FORMAT_ETC2_SIGNED_RG11_EAC:
 475       return GL_COMPRESSED_SIGNED_RG11_EAC;
 476    case MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1:
 477       return GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 478    case MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1:
 479       return GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 480
 481    default:
 482       _mesa_problem(ctx, "Unexpected mesa texture format in"
 483                     " _mesa_compressed_format_to_glenum()");
 484       return 0;
 485    }
 486 }
 487
 488
 489 /*
 490  * Return the address of the pixel at (col, row, img) in a
 491  * compressed texture image.
 492  * \param col, row, img - image position (3D), should be a multiple of the
 493  *                        format's block size.
 494  * \param format - compressed image format
 495  * \param width - image width (stride) in pixels
 496  * \param image - the image address
 497  * \return address of pixel at (row, col, img)
 498  */
 499 GLubyte *
 500 _mesa_compressed_image_address(GLint col, GLint row, GLint img,
 501                                gl_format mesaFormat,
 502                                GLsizei width, const GLubyte *image)
 503 {
 504    /* XXX only 2D images implemented, not 3D */
 505    const GLuint blockSize = _mesa_get_format_bytes(mesaFormat);
 506    GLuint bw, bh;
 507    GLint offset;
 508
 509    _mesa_get_format_block_size(mesaFormat, &bw, &bh);
 510
 511    ASSERT(col % bw == 0);
 512    ASSERT(row % bh == 0);
 513
 514    offset = ((width + bw - 1) / bw) * (row / bh) + col / bw;
 515    offset *= blockSize;
 516
 517    return (GLubyte *) image + offset;
 518 }
 519
 520
 521 /**
 522  * Return a texel-fetch function for the given format, or NULL if
 523  * invalid format.
 524  */
 525 compressed_fetch_func
 526 _mesa_get_compressed_fetch_func(gl_format format)
 527 {
 528    switch (format) {
 529    case MESA_FORMAT_RGB_DXT1:
 530    case MESA_FORMAT_RGBA_DXT1:
 531    case MESA_FORMAT_RGBA_DXT3:
 532    case MESA_FORMAT_RGBA_DXT5:
 533    case MESA_FORMAT_SRGB_DXT1:
 534    case MESA_FORMAT_SRGBA_DXT1:
 535    case MESA_FORMAT_SRGBA_DXT3:
 536    case MESA_FORMAT_SRGBA_DXT5:
 537       return _mesa_get_dxt_fetch_func(format);
 538    case MESA_FORMAT_RGB_FXT1:
 539    case MESA_FORMAT_RGBA_FXT1:
 540       return _mesa_get_fxt_fetch_func(format);
 541    case MESA_FORMAT_RED_RGTC1:
 542    case MESA_FORMAT_L_LATC1:
 543    case MESA_FORMAT_SIGNED_RED_RGTC1:
 544    case MESA_FORMAT_SIGNED_L_LATC1:
 545    case MESA_FORMAT_RG_RGTC2:
 546    case MESA_FORMAT_LA_LATC2:
 547    case MESA_FORMAT_SIGNED_RG_RGTC2:
 548    case MESA_FORMAT_SIGNED_LA_LATC2:
 549       return _mesa_get_compressed_rgtc_func(format);
 550    case MESA_FORMAT_ETC1_RGB8:
 551       return _mesa_get_etc_fetch_func(format);
 552    default:
 553       return NULL;
 554    }
 555 }
 556
 557
 558 /**
 559  * Decompress a compressed texture image, returning a GL_RGBA/GL_FLOAT image.
 560  * \param srcRowStride  stride in bytes between rows of blocks in the
 561  *                      compressed source image.
 562  */
 563 void
 564 _mesa_decompress_image(gl_format format, GLuint width, GLuint height,
 565                        const GLubyte *src, GLint srcRowStride,
 566                        GLfloat *dest)
 567 {
 568    compressed_fetch_func fetch;
 569    GLuint i, j;
 570    GLuint bytes, bw, bh;
 571    GLint stride;
 572
 573    bytes = _mesa_get_format_bytes(format);
 574    _mesa_get_format_block_size(format, &bw, &bh);
 575
 576    fetch = _mesa_get_compressed_fetch_func(format);
 577    if (!fetch) {
 578       _mesa_problem(NULL, "Unexpected format in _mesa_decompress_image()");
 579       return;
 580    }
 581
 582    stride = srcRowStride * bh / bytes;
 583
 584    for (j = 0; j < height; j++) {
 585       for (i = 0; i < width; i++) {
 586          fetch(src, stride, i, j, dest);
 587          dest += 4;
 588       }
 589    }
 590 }