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_BPTC_SIGNED_FLOAT_ARB:
  96    case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_ARB:
  97    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
  98    case GL_COMPRESSED_RGB_FXT1_3DFX:
  99    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
 100    case GL_ETC1_RGB8_OES:
 101    case GL_COMPRESSED_RGB8_ETC2:
 102    case GL_COMPRESSED_SRGB8_ETC2:
 103       return GL_RGB;
 104
 105    case GL_COMPRESSED_RGBA:
 106    case GL_COMPRESSED_SRGB_ALPHA:
 107    case GL_COMPRESSED_RGBA_BPTC_UNORM_ARB:
 108    case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM_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       /* The ES and desktop GL specs diverge here.
 268        *
 269        * In desktop OpenGL, the driver can perform online compression of
 270        * uncompressed texture data.  GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 271        * GL_COMPRESSED_TEXTURE_FORMATS give the application a list of
 272        * formats that it could ask the driver to compress with some
 273        * expectation of quality.  The GL_ARB_texture_compression spec
 274        * calls this "suitable for general-purpose usage."  As noted
 275        * above, this means GL_COMPRESSED_RGBA_S3TC_DXT1_EXT is not
 276        * included in the list.
 277        *
 278        * In OpenGL ES, the driver never performs compression.
 279        * GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 280        * GL_COMPRESSED_TEXTURE_FORMATS give the application a list of
 281        * formats that the driver can receive from the application.  It
 282        * is the *complete* list of formats.  The
 283        * GL_EXT_texture_compression_s3tc spec says:
 284        *
 285        *     "New State for OpenGL ES 2.0.25 and 3.0.2 Specifications
 286        *
 287        *         The queries for NUM_COMPRESSED_TEXTURE_FORMATS and
 288        *         COMPRESSED_TEXTURE_FORMATS include
 289        *         COMPRESSED_RGB_S3TC_DXT1_EXT,
 290        *         COMPRESSED_RGBA_S3TC_DXT1_EXT,
 291        *         COMPRESSED_RGBA_S3TC_DXT3_EXT, and
 292        *         COMPRESSED_RGBA_S3TC_DXT5_EXT."
 293        *
 294        * Note that the addition is only to the OpenGL ES specification!
 295        */
 296       if (_mesa_is_gles(ctx)) {
 297          if (formats) {
 298             formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 299          } else {
 300             n += 1;
 301          }
 302       }
 303    }
 304
 305    /* The GL_OES_compressed_ETC1_RGB8_texture spec says:
 306     *
 307     *     "New State
 308     *
 309     *         The queries for NUM_COMPRESSED_TEXTURE_FORMATS and
 310     *         COMPRESSED_TEXTURE_FORMATS include ETC1_RGB8_OES."
 311     */
 312    if (_mesa_is_gles(ctx)
 313        && ctx->Extensions.OES_compressed_ETC1_RGB8_texture) {
 314       if (formats) {
 315          formats[n++] = GL_ETC1_RGB8_OES;
 316       }
 317       else {
 318          n += 1;
 319       }
 320    }
 321
 322    if (ctx->API == API_OPENGLES) {
 323       if (formats) {
 324          formats[n++] = GL_PALETTE4_RGB8_OES;
 325          formats[n++] = GL_PALETTE4_RGBA8_OES;
 326          formats[n++] = GL_PALETTE4_R5_G6_B5_OES;
 327          formats[n++] = GL_PALETTE4_RGBA4_OES;
 328          formats[n++] = GL_PALETTE4_RGB5_A1_OES;
 329          formats[n++] = GL_PALETTE8_RGB8_OES;
 330          formats[n++] = GL_PALETTE8_RGBA8_OES;
 331          formats[n++] = GL_PALETTE8_R5_G6_B5_OES;
 332          formats[n++] = GL_PALETTE8_RGBA4_OES;
 333          formats[n++] = GL_PALETTE8_RGB5_A1_OES;
 334       }
 335       else {
 336          n += 10;
 337       }
 338    }
 339
 340    if (_mesa_is_gles3(ctx)) {
 341       if (formats) {
 342          formats[n++] = GL_COMPRESSED_RGB8_ETC2;
 343          formats[n++] = GL_COMPRESSED_SRGB8_ETC2;
 344          formats[n++] = GL_COMPRESSED_RGBA8_ETC2_EAC;
 345          formats[n++] = GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 346          formats[n++] = GL_COMPRESSED_R11_EAC;
 347          formats[n++] = GL_COMPRESSED_RG11_EAC;
 348          formats[n++] = GL_COMPRESSED_SIGNED_R11_EAC;
 349          formats[n++] = GL_COMPRESSED_SIGNED_RG11_EAC;
 350          formats[n++] = GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 351          formats[n++] = GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 352       }
 353       else {
 354          n += 10;
 355       }
 356    }
 357    return n;
 358 }
 359
 360
 361 /**
 362  * Convert a compressed MESA_FORMAT_x to a GLenum.
 363  */
 364 mesa_format
 365 _mesa_glenum_to_compressed_format(GLenum format)
 366 {
 367    switch (format) {
 368    case GL_COMPRESSED_RGB_FXT1_3DFX:
 369       return MESA_FORMAT_RGB_FXT1;
 370    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 371       return MESA_FORMAT_RGBA_FXT1;
 372
 373    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
 374    case GL_RGB_S3TC:
 375       return MESA_FORMAT_RGB_DXT1;
 376    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 377    case GL_RGB4_S3TC:
 378       return MESA_FORMAT_RGBA_DXT1;
 379    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 380    case GL_RGBA_S3TC:
 381       return MESA_FORMAT_RGBA_DXT3;
 382    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 383    case GL_RGBA4_S3TC:
 384       return MESA_FORMAT_RGBA_DXT5;
 385
 386    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
 387       return MESA_FORMAT_SRGB_DXT1;
 388    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 389       return MESA_FORMAT_SRGBA_DXT1;
 390    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 391       return MESA_FORMAT_SRGBA_DXT3;
 392    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 393       return MESA_FORMAT_SRGBA_DXT5;
 394
 395    case GL_COMPRESSED_RED_RGTC1:
 396       return MESA_FORMAT_R_RGTC1_UNORM;
 397    case GL_COMPRESSED_SIGNED_RED_RGTC1:
 398       return MESA_FORMAT_R_RGTC1_SNORM;
 399    case GL_COMPRESSED_RG_RGTC2:
 400       return MESA_FORMAT_RG_RGTC2_UNORM;
 401    case GL_COMPRESSED_SIGNED_RG_RGTC2:
 402       return MESA_FORMAT_RG_RGTC2_SNORM;
 403
 404    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 405       return MESA_FORMAT_L_LATC1_UNORM;
 406    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 407       return MESA_FORMAT_L_LATC1_SNORM;
 408    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 409    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 410       return MESA_FORMAT_LA_LATC2_UNORM;
 411    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 412       return MESA_FORMAT_LA_LATC2_SNORM;
 413
 414    case GL_ETC1_RGB8_OES:
 415       return MESA_FORMAT_ETC1_RGB8;
 416    case GL_COMPRESSED_RGB8_ETC2:
 417       return MESA_FORMAT_ETC2_RGB8;
 418    case GL_COMPRESSED_SRGB8_ETC2:
 419       return MESA_FORMAT_ETC2_SRGB8;
 420    case GL_COMPRESSED_RGBA8_ETC2_EAC:
 421       return MESA_FORMAT_ETC2_RGBA8_EAC;
 422    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
 423       return MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC;
 424    case GL_COMPRESSED_R11_EAC:
 425       return MESA_FORMAT_ETC2_R11_EAC;
 426    case GL_COMPRESSED_RG11_EAC:
 427       return MESA_FORMAT_ETC2_RG11_EAC;
 428    case GL_COMPRESSED_SIGNED_R11_EAC:
 429       return MESA_FORMAT_ETC2_SIGNED_R11_EAC;
 430    case GL_COMPRESSED_SIGNED_RG11_EAC:
 431       return MESA_FORMAT_ETC2_SIGNED_RG11_EAC;
 432    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 433       return MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1;
 434    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 435       return MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1;
 436
 437    default:
 438       return MESA_FORMAT_NONE;
 439    }
 440 }
 441
 442
 443 /**
 444  * Given a compressed MESA_FORMAT_x value, return the corresponding
 445  * GLenum for that format.
 446  * This is needed for glGetTexLevelParameter(GL_TEXTURE_INTERNAL_FORMAT)
 447  * which must return the specific texture format used when the user might
 448  * have originally specified a generic compressed format in their
 449  * glTexImage2D() call.
 450  * For non-compressed textures, we always return the user-specified
 451  * internal format unchanged.
 452  */
 453 GLenum
 454 _mesa_compressed_format_to_glenum(struct gl_context *ctx, mesa_format mesaFormat)
 455 {
 456    switch (mesaFormat) {
 457    case MESA_FORMAT_RGB_FXT1:
 458       return GL_COMPRESSED_RGB_FXT1_3DFX;
 459    case MESA_FORMAT_RGBA_FXT1:
 460       return GL_COMPRESSED_RGBA_FXT1_3DFX;
 461    case MESA_FORMAT_RGB_DXT1:
 462       return GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 463    case MESA_FORMAT_RGBA_DXT1:
 464       return GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 465    case MESA_FORMAT_RGBA_DXT3:
 466       return GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 467    case MESA_FORMAT_RGBA_DXT5:
 468       return GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 469    case MESA_FORMAT_SRGB_DXT1:
 470       return GL_COMPRESSED_SRGB_S3TC_DXT1_EXT;
 471    case MESA_FORMAT_SRGBA_DXT1:
 472       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT;
 473    case MESA_FORMAT_SRGBA_DXT3:
 474       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT;
 475    case MESA_FORMAT_SRGBA_DXT5:
 476       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT;
 477    case MESA_FORMAT_R_RGTC1_UNORM:
 478       return GL_COMPRESSED_RED_RGTC1;
 479    case MESA_FORMAT_R_RGTC1_SNORM:
 480       return GL_COMPRESSED_SIGNED_RED_RGTC1;
 481    case MESA_FORMAT_RG_RGTC2_UNORM:
 482       return GL_COMPRESSED_RG_RGTC2;
 483    case MESA_FORMAT_RG_RGTC2_SNORM:
 484       return GL_COMPRESSED_SIGNED_RG_RGTC2;
 485
 486    case MESA_FORMAT_L_LATC1_UNORM:
 487       return GL_COMPRESSED_LUMINANCE_LATC1_EXT;
 488    case MESA_FORMAT_L_LATC1_SNORM:
 489       return GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT;
 490    case MESA_FORMAT_LA_LATC2_UNORM:
 491       return GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT;
 492    case MESA_FORMAT_LA_LATC2_SNORM:
 493       return GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT;
 494
 495    case MESA_FORMAT_ETC1_RGB8:
 496       return GL_ETC1_RGB8_OES;
 497    case MESA_FORMAT_ETC2_RGB8:
 498       return GL_COMPRESSED_RGB8_ETC2;
 499    case MESA_FORMAT_ETC2_SRGB8:
 500       return GL_COMPRESSED_SRGB8_ETC2;
 501    case MESA_FORMAT_ETC2_RGBA8_EAC:
 502       return GL_COMPRESSED_RGBA8_ETC2_EAC;
 503    case MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC:
 504       return GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 505    case MESA_FORMAT_ETC2_R11_EAC:
 506       return GL_COMPRESSED_R11_EAC;
 507    case MESA_FORMAT_ETC2_RG11_EAC:
 508       return GL_COMPRESSED_RG11_EAC;
 509    case MESA_FORMAT_ETC2_SIGNED_R11_EAC:
 510       return GL_COMPRESSED_SIGNED_R11_EAC;
 511    case MESA_FORMAT_ETC2_SIGNED_RG11_EAC:
 512       return GL_COMPRESSED_SIGNED_RG11_EAC;
 513    case MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1:
 514       return GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 515    case MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1:
 516       return GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 517
 518    default:
 519       _mesa_problem(ctx, "Unexpected mesa texture format in"
 520                     " _mesa_compressed_format_to_glenum()");
 521       return 0;
 522    }
 523 }
 524
 525
 526 /*
 527  * Return the address of the pixel at (col, row, img) in a
 528  * compressed texture image.
 529  * \param col, row, img - image position (3D), should be a multiple of the
 530  *                        format's block size.
 531  * \param format - compressed image format
 532  * \param width - image width (stride) in pixels
 533  * \param image - the image address
 534  * \return address of pixel at (row, col, img)
 535  */
 536 GLubyte *
 537 _mesa_compressed_image_address(GLint col, GLint row, GLint img,
 538                                mesa_format mesaFormat,
 539                                GLsizei width, const GLubyte *image)
 540 {
 541    /* XXX only 2D images implemented, not 3D */
 542    const GLuint blockSize = _mesa_get_format_bytes(mesaFormat);
 543    GLuint bw, bh;
 544    GLint offset;
 545
 546    _mesa_get_format_block_size(mesaFormat, &bw, &bh);
 547
 548    ASSERT(col % bw == 0);
 549    ASSERT(row % bh == 0);
 550
 551    offset = ((width + bw - 1) / bw) * (row / bh) + col / bw;
 552    offset *= blockSize;
 553
 554    return (GLubyte *) image + offset;
 555 }
 556
 557
 558 /**
 559  * Return a texel-fetch function for the given format, or NULL if
 560  * invalid format.
 561  */
 562 compressed_fetch_func
 563 _mesa_get_compressed_fetch_func(mesa_format format)
 564 {
 565    switch (format) {
 566    case MESA_FORMAT_RGB_DXT1:
 567    case MESA_FORMAT_RGBA_DXT1:
 568    case MESA_FORMAT_RGBA_DXT3:
 569    case MESA_FORMAT_RGBA_DXT5:
 570    case MESA_FORMAT_SRGB_DXT1:
 571    case MESA_FORMAT_SRGBA_DXT1:
 572    case MESA_FORMAT_SRGBA_DXT3:
 573    case MESA_FORMAT_SRGBA_DXT5:
 574       return _mesa_get_dxt_fetch_func(format);
 575    case MESA_FORMAT_RGB_FXT1:
 576    case MESA_FORMAT_RGBA_FXT1:
 577       return _mesa_get_fxt_fetch_func(format);
 578    case MESA_FORMAT_R_RGTC1_UNORM:
 579    case MESA_FORMAT_L_LATC1_UNORM:
 580    case MESA_FORMAT_R_RGTC1_SNORM:
 581    case MESA_FORMAT_L_LATC1_SNORM:
 582    case MESA_FORMAT_RG_RGTC2_UNORM:
 583    case MESA_FORMAT_LA_LATC2_UNORM:
 584    case MESA_FORMAT_RG_RGTC2_SNORM:
 585    case MESA_FORMAT_LA_LATC2_SNORM:
 586       return _mesa_get_compressed_rgtc_func(format);
 587    case MESA_FORMAT_ETC1_RGB8:
 588       return _mesa_get_etc_fetch_func(format);
 589    default:
 590       return NULL;
 591    }
 592 }
 593
 594
 595 /**
 596  * Decompress a compressed texture image, returning a GL_RGBA/GL_FLOAT image.
 597  * \param srcRowStride  stride in bytes between rows of blocks in the
 598  *                      compressed source image.
 599  */
 600 void
 601 _mesa_decompress_image(mesa_format format, GLuint width, GLuint height,
 602                        const GLubyte *src, GLint srcRowStride,
 603                        GLfloat *dest)
 604 {
 605    compressed_fetch_func fetch;
 606    GLuint i, j;
 607    GLuint bytes, bw, bh;
 608    GLint stride;
 609
 610    bytes = _mesa_get_format_bytes(format);
 611    _mesa_get_format_block_size(format, &bw, &bh);
 612
 613    fetch = _mesa_get_compressed_fetch_func(format);
 614    if (!fetch) {
 615       _mesa_problem(NULL, "Unexpected format in _mesa_decompress_image()");
 616       return;
 617    }
 618
 619    stride = srcRowStride * bh / bytes;
 620
 621    for (j = 0; j < height; j++) {
 622       for (i = 0; i < width; i++) {
 623          fetch(src, stride, i, j, dest);
 624          dest += 4;
 625       }
 626    }
 627 }