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  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  22  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  23  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  * OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27
  28 /**
  29  * \file texcompress.c
  30  * Helper functions for texture compression.
  31  */
  32
  33
  34 #include "glheader.h"
  35 #include "imports.h"
  36 #include "colormac.h"
  37 #include "context.h"
  38 #include "formats.h"
  39 #include "mtypes.h"
  40 #include "context.h"
  41 #include "texcompress.h"
  42 #include "texcompress_fxt1.h"
  43 #include "texcompress_rgtc.h"
  44 #include "texcompress_s3tc.h"
  45 #include "texcompress_etc.h"
  46
  47
  48 /**
  49  * Get the GL base format of a specified GL compressed texture format
  50  *
  51  * From page 232 of the OpenGL 3.3 (Compatiblity Profile) spec:
  52  *
  53  *     "Compressed Internal Format      Base Internal Format    Type
  54  *     ---------------------------     --------------------    ---------
  55  *     COMPRESSED_ALPHA                ALPHA                   Generic
  56  *     COMPRESSED_LUMINANCE            LUMINANCE               Generic
  57  *     COMPRESSED_LUMINANCE_ALPHA      LUMINANCE_ALPHA         Generic
  58  *     COMPRESSED_INTENSITY            INTENSITY               Generic
  59  *     COMPRESSED_RED                  RED                     Generic
  60  *     COMPRESSED_RG                   RG                      Generic
  61  *     COMPRESSED_RGB                  RGB                     Generic
  62  *     COMPRESSED_RGBA                 RGBA                    Generic
  63  *     COMPRESSED_SRGB                 RGB                     Generic
  64  *     COMPRESSED_SRGB_ALPHA           RGBA                    Generic
  65  *     COMPRESSED_SLUMINANCE           LUMINANCE               Generic
  66  *     COMPRESSED_SLUMINANCE_ALPHA     LUMINANCE_ALPHA         Generic
  67  *     COMPRESSED_RED_RGTC1            RED                     Specific
  68  *     COMPRESSED_SIGNED_RED_RGTC1     RED                     Specific
  69  *     COMPRESSED_RG_RGTC2             RG                      Specific
  70  *     COMPRESSED_SIGNED_RG_RGTC2      RG                      Specific"
  71  *
  72  * \return
  73  * The base format of \c format if \c format is a compressed format (either
  74  * generic or specific.  Otherwise 0 is returned.
  75  */
  76 GLenum
  77 _mesa_gl_compressed_format_base_format(GLenum format)
  78 {
  79    switch (format) {
  80    case GL_COMPRESSED_RED:
  81    case GL_COMPRESSED_R11_EAC:
  82    case GL_COMPRESSED_RED_RGTC1:
  83    case GL_COMPRESSED_SIGNED_R11_EAC:
  84    case GL_COMPRESSED_SIGNED_RED_RGTC1:
  85       return GL_RED;
  86
  87    case GL_COMPRESSED_RG:
  88    case GL_COMPRESSED_RG11_EAC:
  89    case GL_COMPRESSED_RG_RGTC2:
  90    case GL_COMPRESSED_SIGNED_RG11_EAC:
  91    case GL_COMPRESSED_SIGNED_RG_RGTC2:
  92       return GL_RG;
  93
  94    case GL_COMPRESSED_RGB:
  95    case GL_COMPRESSED_SRGB:
  96    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
  97    case GL_COMPRESSED_RGB_FXT1_3DFX:
  98    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
  99    case GL_ETC1_RGB8_OES:
 100    case GL_COMPRESSED_RGB8_ETC2:
 101    case GL_COMPRESSED_SRGB8_ETC2:
 102       return GL_RGB;
 103
 104    case GL_COMPRESSED_RGBA:
 105    case GL_COMPRESSED_SRGB_ALPHA:
 106    case GL_COMPRESSED_RGBA_BPTC_UNORM_ARB:
 107    case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM_ARB:
 108    case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT_ARB:
 109    case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_ARB:
 110    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 111    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 112    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 113    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 114    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 115    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 116    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 117    case GL_COMPRESSED_RGBA8_ETC2_EAC:
 118    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
 119    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 120    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 121       return GL_RGBA;
 122
 123    case GL_COMPRESSED_ALPHA:
 124       return GL_ALPHA;
 125
 126    case GL_COMPRESSED_LUMINANCE:
 127    case GL_COMPRESSED_SLUMINANCE:
 128    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 129    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 130       return GL_LUMINANCE;
 131
 132    case GL_COMPRESSED_LUMINANCE_ALPHA:
 133    case GL_COMPRESSED_SLUMINANCE_ALPHA:
 134    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 135    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 136    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 137       return GL_LUMINANCE_ALPHA;
 138
 139    case GL_COMPRESSED_INTENSITY:
 140       return GL_INTENSITY;
 141
 142    default:
 143       return 0;
 144    }
 145 }
 146
 147 /**
 148  * Return list of (and count of) all specific texture compression
 149  * formats that are supported.
 150  *
 151  * Some formats are \b not returned by this function.  The
 152  * \c GL_COMPRESSED_TEXTURE_FORMATS query only returns formats that are
 153  * "suitable for general-purpose usage."  All texture compression extensions
 154  * have taken this to mean either linear RGB or linear RGBA.
 155  *
 156  * The GL_ARB_texture_compress_rgtc spec says:
 157  *
 158  *    "19) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 159  *        GL_COMPRESSED_TEXTURE_FORMATS queries return the RGTC formats?
 160  *
 161  *        RESOLVED:  No.
 162  *
 163  *        The OpenGL 2.1 specification says "The only values returned
 164  *        by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those
 165  *        corresponding to formats suitable for general-purpose usage.
 166  *        The renderer will not enumerate formats with restrictions that
 167  *        need to be specifically understood prior to use."
 168  *
 169  *        Compressed textures with just red or red-green components are
 170  *        not general-purpose so should not be returned by these queries
 171  *        because they have restrictions.
 172  *
 173  *        Applications that seek to use the RGTC formats should do so
 174  *        by looking for this extension's name in the string returned by
 175  *        glGetString(GL_EXTENSIONS) rather than
 176  *        what GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 177  *        GL_COMPRESSED_TEXTURE_FORMATS return."
 178  *
 179  * There is nearly identical wording in the GL_EXT_texture_compression_rgtc
 180  * spec.
 181  *
 182  * The GL_EXT_texture_rRGB spec says:
 183  *
 184  *    "22) Should the new COMPRESSED_SRGB_* formats be listed in an
 185  *        implementation's GL_COMPRESSED_TEXTURE_FORMATS list?
 186  *
 187  *        RESOLVED:  No.  Section 3.8.1 says formats listed by
 188  *        GL_COMPRESSED_TEXTURE_FORMATS are "suitable for general-purpose
 189  *        usage."  The non-linear distribution of red, green, and
 190  *        blue for these sRGB compressed formats makes them not really
 191  *        general-purpose."
 192  *
 193  * The GL_EXT_texture_compression_latc spec says:
 194  *
 195  *    "16) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 196  *        GL_COMPRESSED_TEXTURE_FORMATS queries return the LATC formats?
 197  *
 198  *        RESOLVED:  No.
 199  *
 200  *        The OpenGL 2.1 specification says "The only values returned
 201  *        by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those
 202  *        corresponding to formats suitable for general-purpose usage.
 203  *        The renderer will not enumerate formats with restrictions that
 204  *        need to be specifically understood prior to use."
 205  *
 206  *        Historically, OpenGL implementation have advertised the RGB and
 207  *        RGBA versions of the S3TC extensions compressed format tokens
 208  *        through this mechanism.
 209  *
 210  *        The specification is not sufficiently clear about what "suitable
 211  *        for general-purpose usage" means.  Historically that seems to mean
 212  *        unsigned RGB or unsigned RGBA.  The DXT1 format supporting alpha
 213  *        (GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) is not exposed in the list (at
 214  *        least for NVIDIA drivers) because the alpha is always 1.0 expect
 215  *        when it is 0.0 when RGB is required to be black.  NVIDIA's even
 216  *        limits itself to true linear RGB or RGBA formats, specifically
 217  *        not including EXT_texture_sRGB's sRGB S3TC compressed formats.
 218  *
 219  *        Adding luminance and luminance-alpha texture formats (and
 220  *        certainly signed versions of luminance and luminance-alpha
 221  *        formats!) invites potential comptaibility problems with old
 222  *        applications using this mechanism since old applications are
 223  *        unlikely to expect non-RGB or non-RGBA formats to be advertised
 224  *        through this mechanism.  However no specific misinteractions
 225  *        with old applications is known.
 226  *
 227  *        Applications that seek to use the LATC formats should do so
 228  *        by looking for this extension's name in the string returned by
 229  *        glGetString(GL_EXTENSIONS) rather than
 230  *        what GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 231  *        GL_COMPRESSED_TEXTURE_FORMATS return."
 232  *
 233  * There is no formal spec for GL_ATI_texture_compression_3dc.  Since the
 234  * formats added by this extension are luminance-alpha formats, it is
 235  * reasonable to expect them to follow the same rules as
 236  * GL_EXT_texture_compression_latc.  At the very least, Catalyst 11.6 does not
 237  * expose the 3dc formats through this mechanism.
 238  *
 239  * \param ctx  the GL context
 240  * \param formats  the resulting format list (may be NULL).
 241  *
 242  * \return number of formats.
 243  */
 244 GLuint
 245 _mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats)
 246 {
 247    GLuint n = 0;
 248    if (ctx->Extensions.TDFX_texture_compression_FXT1) {
 249       if (formats) {
 250          formats[n++] = GL_COMPRESSED_RGB_FXT1_3DFX;
 251          formats[n++] = GL_COMPRESSED_RGBA_FXT1_3DFX;
 252       }
 253       else {
 254          n += 2;
 255       }
 256    }
 257
 258    if (ctx->Extensions.EXT_texture_compression_s3tc) {
 259       if (formats) {
 260          formats[n++] = GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 261          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 262          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 263       }
 264       else {
 265          n += 3;
 266       }
 267    }
 268    if (_mesa_is_desktop_gl(ctx)
 269        && ctx->Extensions.ANGLE_texture_compression_dxt) {
 270       if (formats) {
 271          formats[n++] = GL_RGB_S3TC;
 272          formats[n++] = GL_RGB4_S3TC;
 273          formats[n++] = GL_RGBA_S3TC;
 274          formats[n++] = GL_RGBA4_S3TC;
 275       }
 276       else {
 277          n += 4;
 278       }
 279    }
 280
 281    if (ctx->Extensions.OES_compressed_ETC1_RGB8_texture) {
 282       if (formats) {
 283          formats[n++] = GL_ETC1_RGB8_OES;
 284       }
 285       else {
 286          n += 1;
 287       }
 288    }
 289
 290    if (ctx->API == API_OPENGLES) {
 291       if (formats) {
 292          formats[n++] = GL_PALETTE4_RGB8_OES;
 293          formats[n++] = GL_PALETTE4_RGBA8_OES;
 294          formats[n++] = GL_PALETTE4_R5_G6_B5_OES;
 295          formats[n++] = GL_PALETTE4_RGBA4_OES;
 296          formats[n++] = GL_PALETTE4_RGB5_A1_OES;
 297          formats[n++] = GL_PALETTE8_RGB8_OES;
 298          formats[n++] = GL_PALETTE8_RGBA8_OES;
 299          formats[n++] = GL_PALETTE8_R5_G6_B5_OES;
 300          formats[n++] = GL_PALETTE8_RGBA4_OES;
 301          formats[n++] = GL_PALETTE8_RGB5_A1_OES;
 302       }
 303       else {
 304          n += 10;
 305       }
 306    }
 307
 308    if (_mesa_is_gles3(ctx)) {
 309       if (formats) {
 310          formats[n++] = GL_COMPRESSED_RGB8_ETC2;
 311          formats[n++] = GL_COMPRESSED_SRGB8_ETC2;
 312          formats[n++] = GL_COMPRESSED_RGBA8_ETC2_EAC;
 313          formats[n++] = GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 314          formats[n++] = GL_COMPRESSED_R11_EAC;
 315          formats[n++] = GL_COMPRESSED_RG11_EAC;
 316          formats[n++] = GL_COMPRESSED_SIGNED_R11_EAC;
 317          formats[n++] = GL_COMPRESSED_SIGNED_RG11_EAC;
 318          formats[n++] = GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 319          formats[n++] = GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 320       }
 321       else {
 322          n += 10;
 323       }
 324    }
 325    return n;
 326 }
 327
 328
 329 /**
 330  * Convert a compressed MESA_FORMAT_x to a GLenum.
 331  */
 332 gl_format
 333 _mesa_glenum_to_compressed_format(GLenum format)
 334 {
 335    switch (format) {
 336    case GL_COMPRESSED_RGB_FXT1_3DFX:
 337       return MESA_FORMAT_RGB_FXT1;
 338    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 339       return MESA_FORMAT_RGBA_FXT1;
 340
 341    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
 342    case GL_RGB_S3TC:
 343       return MESA_FORMAT_RGB_DXT1;
 344    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 345    case GL_RGB4_S3TC:
 346       return MESA_FORMAT_RGBA_DXT1;
 347    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 348    case GL_RGBA_S3TC:
 349       return MESA_FORMAT_RGBA_DXT3;
 350    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 351    case GL_RGBA4_S3TC:
 352       return MESA_FORMAT_RGBA_DXT5;
 353
 354    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
 355       return MESA_FORMAT_SRGB_DXT1;
 356    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 357       return MESA_FORMAT_SRGBA_DXT1;
 358    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 359       return MESA_FORMAT_SRGBA_DXT3;
 360    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 361       return MESA_FORMAT_SRGBA_DXT5;
 362
 363    case GL_COMPRESSED_RED_RGTC1:
 364       return MESA_FORMAT_RED_RGTC1;
 365    case GL_COMPRESSED_SIGNED_RED_RGTC1:
 366       return MESA_FORMAT_SIGNED_RED_RGTC1;
 367    case GL_COMPRESSED_RG_RGTC2:
 368       return MESA_FORMAT_RG_RGTC2;
 369    case GL_COMPRESSED_SIGNED_RG_RGTC2:
 370       return MESA_FORMAT_SIGNED_RG_RGTC2;
 371
 372    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 373       return MESA_FORMAT_L_LATC1;
 374    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 375       return MESA_FORMAT_SIGNED_L_LATC1;
 376    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 377    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 378       return MESA_FORMAT_LA_LATC2;
 379    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 380       return MESA_FORMAT_SIGNED_LA_LATC2;
 381
 382    case GL_ETC1_RGB8_OES:
 383       return MESA_FORMAT_ETC1_RGB8;
 384    case GL_COMPRESSED_RGB8_ETC2:
 385       return MESA_FORMAT_ETC2_RGB8;
 386    case GL_COMPRESSED_SRGB8_ETC2:
 387       return MESA_FORMAT_ETC2_SRGB8;
 388    case GL_COMPRESSED_RGBA8_ETC2_EAC:
 389       return MESA_FORMAT_ETC2_RGBA8_EAC;
 390    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
 391       return MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC;
 392    case GL_COMPRESSED_R11_EAC:
 393       return MESA_FORMAT_ETC2_R11_EAC;
 394    case GL_COMPRESSED_RG11_EAC:
 395       return MESA_FORMAT_ETC2_RG11_EAC;
 396    case GL_COMPRESSED_SIGNED_R11_EAC:
 397       return MESA_FORMAT_ETC2_SIGNED_R11_EAC;
 398    case GL_COMPRESSED_SIGNED_RG11_EAC:
 399       return MESA_FORMAT_ETC2_SIGNED_RG11_EAC;
 400    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 401       return MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1;
 402    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 403       return MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1;
 404
 405    default:
 406       return MESA_FORMAT_NONE;
 407    }
 408 }
 409
 410
 411 /**
 412  * Given a compressed MESA_FORMAT_x value, return the corresponding
 413  * GLenum for that format.
 414  * This is needed for glGetTexLevelParameter(GL_TEXTURE_INTERNAL_FORMAT)
 415  * which must return the specific texture format used when the user might
 416  * have originally specified a generic compressed format in their
 417  * glTexImage2D() call.
 418  * For non-compressed textures, we always return the user-specified
 419  * internal format unchanged.
 420  */
 421 GLenum
 422 _mesa_compressed_format_to_glenum(struct gl_context *ctx, gl_format mesaFormat)
 423 {
 424    switch (mesaFormat) {
 425    case MESA_FORMAT_RGB_FXT1:
 426       return GL_COMPRESSED_RGB_FXT1_3DFX;
 427    case MESA_FORMAT_RGBA_FXT1:
 428       return GL_COMPRESSED_RGBA_FXT1_3DFX;
 429    case MESA_FORMAT_RGB_DXT1:
 430       return GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 431    case MESA_FORMAT_RGBA_DXT1:
 432       return GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 433    case MESA_FORMAT_RGBA_DXT3:
 434       return GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 435    case MESA_FORMAT_RGBA_DXT5:
 436       return GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 437    case MESA_FORMAT_SRGB_DXT1:
 438       return GL_COMPRESSED_SRGB_S3TC_DXT1_EXT;
 439    case MESA_FORMAT_SRGBA_DXT1:
 440       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT;
 441    case MESA_FORMAT_SRGBA_DXT3:
 442       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT;
 443    case MESA_FORMAT_SRGBA_DXT5:
 444       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT;
 445    case MESA_FORMAT_RED_RGTC1:
 446       return GL_COMPRESSED_RED_RGTC1;
 447    case MESA_FORMAT_SIGNED_RED_RGTC1:
 448       return GL_COMPRESSED_SIGNED_RED_RGTC1;
 449    case MESA_FORMAT_RG_RGTC2:
 450       return GL_COMPRESSED_RG_RGTC2;
 451    case MESA_FORMAT_SIGNED_RG_RGTC2:
 452       return GL_COMPRESSED_SIGNED_RG_RGTC2;
 453
 454    case MESA_FORMAT_L_LATC1:
 455       return GL_COMPRESSED_LUMINANCE_LATC1_EXT;
 456    case MESA_FORMAT_SIGNED_L_LATC1:
 457       return GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT;
 458    case MESA_FORMAT_LA_LATC2:
 459       return GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT;
 460    case MESA_FORMAT_SIGNED_LA_LATC2:
 461       return GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT;
 462
 463    case MESA_FORMAT_ETC1_RGB8:
 464       return GL_ETC1_RGB8_OES;
 465    case MESA_FORMAT_ETC2_RGB8:
 466       return GL_COMPRESSED_RGB8_ETC2;
 467    case MESA_FORMAT_ETC2_SRGB8:
 468       return GL_COMPRESSED_SRGB8_ETC2;
 469    case MESA_FORMAT_ETC2_RGBA8_EAC:
 470       return GL_COMPRESSED_RGBA8_ETC2_EAC;
 471    case MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC:
 472       return GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 473    case MESA_FORMAT_ETC2_R11_EAC:
 474       return GL_COMPRESSED_R11_EAC;
 475    case MESA_FORMAT_ETC2_RG11_EAC:
 476       return GL_COMPRESSED_RG11_EAC;
 477    case MESA_FORMAT_ETC2_SIGNED_R11_EAC:
 478       return GL_COMPRESSED_SIGNED_R11_EAC;
 479    case MESA_FORMAT_ETC2_SIGNED_RG11_EAC:
 480       return GL_COMPRESSED_SIGNED_RG11_EAC;
 481    case MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1:
 482       return GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 483    case MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1:
 484       return GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 485
 486    default:
 487       _mesa_problem(ctx, "Unexpected mesa texture format in"
 488                     " _mesa_compressed_format_to_glenum()");
 489       return 0;
 490    }
 491 }
 492
 493
 494 /*
 495  * Return the address of the pixel at (col, row, img) in a
 496  * compressed texture image.
 497  * \param col, row, img - image position (3D), should be a multiple of the
 498  *                        format's block size.
 499  * \param format - compressed image format
 500  * \param width - image width (stride) in pixels
 501  * \param image - the image address
 502  * \return address of pixel at (row, col, img)
 503  */
 504 GLubyte *
 505 _mesa_compressed_image_address(GLint col, GLint row, GLint img,
 506                                gl_format mesaFormat,
 507                                GLsizei width, const GLubyte *image)
 508 {
 509    /* XXX only 2D images implemented, not 3D */
 510    const GLuint blockSize = _mesa_get_format_bytes(mesaFormat);
 511    GLuint bw, bh;
 512    GLint offset;
 513
 514    _mesa_get_format_block_size(mesaFormat, &bw, &bh);
 515
 516    ASSERT(col % bw == 0);
 517    ASSERT(row % bh == 0);
 518
 519    offset = ((width + bw - 1) / bw) * (row / bh) + col / bw;
 520    offset *= blockSize;
 521
 522    return (GLubyte *) image + offset;
 523 }
 524
 525
 526 /**
 527  * Return a texel-fetch function for the given format, or NULL if
 528  * invalid format.
 529  */
 530 compressed_fetch_func
 531 _mesa_get_compressed_fetch_func(gl_format format)
 532 {
 533    switch (format) {
 534    case MESA_FORMAT_RGB_DXT1:
 535    case MESA_FORMAT_RGBA_DXT1:
 536    case MESA_FORMAT_RGBA_DXT3:
 537    case MESA_FORMAT_RGBA_DXT5:
 538    case MESA_FORMAT_SRGB_DXT1:
 539    case MESA_FORMAT_SRGBA_DXT1:
 540    case MESA_FORMAT_SRGBA_DXT3:
 541    case MESA_FORMAT_SRGBA_DXT5:
 542       return _mesa_get_dxt_fetch_func(format);
 543    case MESA_FORMAT_RGB_FXT1:
 544    case MESA_FORMAT_RGBA_FXT1:
 545       return _mesa_get_fxt_fetch_func(format);
 546    case MESA_FORMAT_RED_RGTC1:
 547    case MESA_FORMAT_L_LATC1:
 548    case MESA_FORMAT_SIGNED_RED_RGTC1:
 549    case MESA_FORMAT_SIGNED_L_LATC1:
 550    case MESA_FORMAT_RG_RGTC2:
 551    case MESA_FORMAT_LA_LATC2:
 552    case MESA_FORMAT_SIGNED_RG_RGTC2:
 553    case MESA_FORMAT_SIGNED_LA_LATC2:
 554       return _mesa_get_compressed_rgtc_func(format);
 555    case MESA_FORMAT_ETC1_RGB8:
 556       return _mesa_get_etc_fetch_func(format);
 557    default:
 558       return NULL;
 559    }
 560 }
 561
 562
 563 /**
 564  * Decompress a compressed texture image, returning a GL_RGBA/GL_FLOAT image.
 565  * \param srcRowStride  stride in bytes between rows of blocks in the
 566  *                      compressed source image.
 567  */
 568 void
 569 _mesa_decompress_image(gl_format format, GLuint width, GLuint height,
 570                        const GLubyte *src, GLint srcRowStride,
 571                        GLfloat *dest)
 572 {
 573    compressed_fetch_func fetch;
 574    GLuint i, j;
 575    GLuint bytes, bw, bh;
 576    GLint stride;
 577
 578    bytes = _mesa_get_format_bytes(format);
 579    _mesa_get_format_block_size(format, &bw, &bh);
 580
 581    fetch = _mesa_get_compressed_fetch_func(format);
 582    if (!fetch) {
 583       _mesa_problem(NULL, "Unexpected format in _mesa_decompress_image()");
 584       return;
 585    }
 586
 587    stride = srcRowStride * bh / bytes;
 588
 589    for (j = 0; j < height; j++) {
 590       for (i = 0; i < width; i++) {
 591          fetch(src, NULL, stride, i, j, 0, dest);
 592          dest += 4;
 593       }
 594    }
 595 }