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 "context.h"
  36 #include "formats.h"
  37 #include "mtypes.h"
  38 #include "context.h"
  39 #include "texcompress.h"
  40 #include "texcompress_fxt1.h"
  41 #include "texcompress_rgtc.h"
  42 #include "texcompress_s3tc.h"
  43 #include "texcompress_etc.h"
  44 #include "texcompress_bptc.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  * The spec for GL_ARB_texture_compression_bptc doesn't mention whether it
 239  * should be included in GL_COMPRESSED_TEXTURE_FORMATS. However as it takes a
 240  * very long time to compress the textures in this format it's probably not
 241  * very useful as a general format where the GL will have to compress it on
 242  * the fly.
 243  *
 244  * \param ctx  the GL context
 245  * \param formats  the resulting format list (may be NULL).
 246  *
 247  * \return number of formats.
 248  */
 249 GLuint
 250 _mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats)
 251 {
 252    GLuint n = 0;
 253    if (ctx->Extensions.TDFX_texture_compression_FXT1) {
 254       if (formats) {
 255          formats[n++] = GL_COMPRESSED_RGB_FXT1_3DFX;
 256          formats[n++] = GL_COMPRESSED_RGBA_FXT1_3DFX;
 257       }
 258       else {
 259          n += 2;
 260       }
 261    }
 262
 263    if (ctx->Extensions.EXT_texture_compression_s3tc) {
 264       if (formats) {
 265          formats[n++] = GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 266          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 267          formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 268       }
 269       else {
 270          n += 3;
 271       }
 272
 273       /* The ES and desktop GL specs diverge here.
 274        *
 275        * In desktop OpenGL, the driver can perform online compression of
 276        * uncompressed texture data.  GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 277        * GL_COMPRESSED_TEXTURE_FORMATS give the application a list of
 278        * formats that it could ask the driver to compress with some
 279        * expectation of quality.  The GL_ARB_texture_compression spec
 280        * calls this "suitable for general-purpose usage."  As noted
 281        * above, this means GL_COMPRESSED_RGBA_S3TC_DXT1_EXT is not
 282        * included in the list.
 283        *
 284        * In OpenGL ES, the driver never performs compression.
 285        * GL_NUM_COMPRESSED_TEXTURE_FORMATS and
 286        * GL_COMPRESSED_TEXTURE_FORMATS give the application a list of
 287        * formats that the driver can receive from the application.  It
 288        * is the *complete* list of formats.  The
 289        * GL_EXT_texture_compression_s3tc spec says:
 290        *
 291        *     "New State for OpenGL ES 2.0.25 and 3.0.2 Specifications
 292        *
 293        *         The queries for NUM_COMPRESSED_TEXTURE_FORMATS and
 294        *         COMPRESSED_TEXTURE_FORMATS include
 295        *         COMPRESSED_RGB_S3TC_DXT1_EXT,
 296        *         COMPRESSED_RGBA_S3TC_DXT1_EXT,
 297        *         COMPRESSED_RGBA_S3TC_DXT3_EXT, and
 298        *         COMPRESSED_RGBA_S3TC_DXT5_EXT."
 299        *
 300        * Note that the addition is only to the OpenGL ES specification!
 301        */
 302       if (_mesa_is_gles(ctx)) {
 303          if (formats) {
 304             formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 305          } else {
 306             n += 1;
 307          }
 308       }
 309    }
 310
 311    /* The GL_OES_compressed_ETC1_RGB8_texture spec says:
 312     *
 313     *     "New State
 314     *
 315     *         The queries for NUM_COMPRESSED_TEXTURE_FORMATS and
 316     *         COMPRESSED_TEXTURE_FORMATS include ETC1_RGB8_OES."
 317     */
 318    if (_mesa_is_gles(ctx)
 319        && ctx->Extensions.OES_compressed_ETC1_RGB8_texture) {
 320       if (formats) {
 321          formats[n++] = GL_ETC1_RGB8_OES;
 322       }
 323       else {
 324          n += 1;
 325       }
 326    }
 327
 328    if (ctx->API == API_OPENGLES) {
 329       if (formats) {
 330          formats[n++] = GL_PALETTE4_RGB8_OES;
 331          formats[n++] = GL_PALETTE4_RGBA8_OES;
 332          formats[n++] = GL_PALETTE4_R5_G6_B5_OES;
 333          formats[n++] = GL_PALETTE4_RGBA4_OES;
 334          formats[n++] = GL_PALETTE4_RGB5_A1_OES;
 335          formats[n++] = GL_PALETTE8_RGB8_OES;
 336          formats[n++] = GL_PALETTE8_RGBA8_OES;
 337          formats[n++] = GL_PALETTE8_R5_G6_B5_OES;
 338          formats[n++] = GL_PALETTE8_RGBA4_OES;
 339          formats[n++] = GL_PALETTE8_RGB5_A1_OES;
 340       }
 341       else {
 342          n += 10;
 343       }
 344    }
 345
 346    if (_mesa_is_gles3(ctx)) {
 347       if (formats) {
 348          formats[n++] = GL_COMPRESSED_RGB8_ETC2;
 349          formats[n++] = GL_COMPRESSED_SRGB8_ETC2;
 350          formats[n++] = GL_COMPRESSED_RGBA8_ETC2_EAC;
 351          formats[n++] = GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 352          formats[n++] = GL_COMPRESSED_R11_EAC;
 353          formats[n++] = GL_COMPRESSED_RG11_EAC;
 354          formats[n++] = GL_COMPRESSED_SIGNED_R11_EAC;
 355          formats[n++] = GL_COMPRESSED_SIGNED_RG11_EAC;
 356          formats[n++] = GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 357          formats[n++] = GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 358       }
 359       else {
 360          n += 10;
 361       }
 362    }
 363    return n;
 364 }
 365
 366
 367 /**
 368  * Convert a compressed MESA_FORMAT_x to a GLenum.
 369  */
 370 mesa_format
 371 _mesa_glenum_to_compressed_format(GLenum format)
 372 {
 373    switch (format) {
 374    case GL_COMPRESSED_RGB_FXT1_3DFX:
 375       return MESA_FORMAT_RGB_FXT1;
 376    case GL_COMPRESSED_RGBA_FXT1_3DFX:
 377       return MESA_FORMAT_RGBA_FXT1;
 378
 379    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
 380    case GL_RGB_S3TC:
 381       return MESA_FORMAT_RGB_DXT1;
 382    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
 383    case GL_RGB4_S3TC:
 384       return MESA_FORMAT_RGBA_DXT1;
 385    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
 386    case GL_RGBA_S3TC:
 387       return MESA_FORMAT_RGBA_DXT3;
 388    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
 389    case GL_RGBA4_S3TC:
 390       return MESA_FORMAT_RGBA_DXT5;
 391
 392    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
 393       return MESA_FORMAT_SRGB_DXT1;
 394    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
 395       return MESA_FORMAT_SRGBA_DXT1;
 396    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
 397       return MESA_FORMAT_SRGBA_DXT3;
 398    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
 399       return MESA_FORMAT_SRGBA_DXT5;
 400
 401    case GL_COMPRESSED_RED_RGTC1:
 402       return MESA_FORMAT_R_RGTC1_UNORM;
 403    case GL_COMPRESSED_SIGNED_RED_RGTC1:
 404       return MESA_FORMAT_R_RGTC1_SNORM;
 405    case GL_COMPRESSED_RG_RGTC2:
 406       return MESA_FORMAT_RG_RGTC2_UNORM;
 407    case GL_COMPRESSED_SIGNED_RG_RGTC2:
 408       return MESA_FORMAT_RG_RGTC2_SNORM;
 409
 410    case GL_COMPRESSED_LUMINANCE_LATC1_EXT:
 411       return MESA_FORMAT_L_LATC1_UNORM;
 412    case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT:
 413       return MESA_FORMAT_L_LATC1_SNORM;
 414    case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT:
 415    case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI:
 416       return MESA_FORMAT_LA_LATC2_UNORM;
 417    case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT:
 418       return MESA_FORMAT_LA_LATC2_SNORM;
 419
 420    case GL_ETC1_RGB8_OES:
 421       return MESA_FORMAT_ETC1_RGB8;
 422    case GL_COMPRESSED_RGB8_ETC2:
 423       return MESA_FORMAT_ETC2_RGB8;
 424    case GL_COMPRESSED_SRGB8_ETC2:
 425       return MESA_FORMAT_ETC2_SRGB8;
 426    case GL_COMPRESSED_RGBA8_ETC2_EAC:
 427       return MESA_FORMAT_ETC2_RGBA8_EAC;
 428    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
 429       return MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC;
 430    case GL_COMPRESSED_R11_EAC:
 431       return MESA_FORMAT_ETC2_R11_EAC;
 432    case GL_COMPRESSED_RG11_EAC:
 433       return MESA_FORMAT_ETC2_RG11_EAC;
 434    case GL_COMPRESSED_SIGNED_R11_EAC:
 435       return MESA_FORMAT_ETC2_SIGNED_R11_EAC;
 436    case GL_COMPRESSED_SIGNED_RG11_EAC:
 437       return MESA_FORMAT_ETC2_SIGNED_RG11_EAC;
 438    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 439       return MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1;
 440    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
 441       return MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1;
 442
 443    case GL_COMPRESSED_RGBA_BPTC_UNORM:
 444       return MESA_FORMAT_BPTC_RGBA_UNORM;
 445    case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM:
 446       return MESA_FORMAT_BPTC_SRGB_ALPHA_UNORM;
 447    case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT:
 448       return MESA_FORMAT_BPTC_RGB_SIGNED_FLOAT;
 449    case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT:
 450       return MESA_FORMAT_BPTC_RGB_UNSIGNED_FLOAT;
 451
 452    default:
 453       return MESA_FORMAT_NONE;
 454    }
 455 }
 456
 457
 458 /**
 459  * Given a compressed MESA_FORMAT_x value, return the corresponding
 460  * GLenum for that format.
 461  * This is needed for glGetTexLevelParameter(GL_TEXTURE_INTERNAL_FORMAT)
 462  * which must return the specific texture format used when the user might
 463  * have originally specified a generic compressed format in their
 464  * glTexImage2D() call.
 465  * For non-compressed textures, we always return the user-specified
 466  * internal format unchanged.
 467  */
 468 GLenum
 469 _mesa_compressed_format_to_glenum(struct gl_context *ctx, mesa_format mesaFormat)
 470 {
 471    switch (mesaFormat) {
 472    case MESA_FORMAT_RGB_FXT1:
 473       return GL_COMPRESSED_RGB_FXT1_3DFX;
 474    case MESA_FORMAT_RGBA_FXT1:
 475       return GL_COMPRESSED_RGBA_FXT1_3DFX;
 476    case MESA_FORMAT_RGB_DXT1:
 477       return GL_COMPRESSED_RGB_S3TC_DXT1_EXT;
 478    case MESA_FORMAT_RGBA_DXT1:
 479       return GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
 480    case MESA_FORMAT_RGBA_DXT3:
 481       return GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
 482    case MESA_FORMAT_RGBA_DXT5:
 483       return GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
 484    case MESA_FORMAT_SRGB_DXT1:
 485       return GL_COMPRESSED_SRGB_S3TC_DXT1_EXT;
 486    case MESA_FORMAT_SRGBA_DXT1:
 487       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT;
 488    case MESA_FORMAT_SRGBA_DXT3:
 489       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT;
 490    case MESA_FORMAT_SRGBA_DXT5:
 491       return GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT;
 492    case MESA_FORMAT_R_RGTC1_UNORM:
 493       return GL_COMPRESSED_RED_RGTC1;
 494    case MESA_FORMAT_R_RGTC1_SNORM:
 495       return GL_COMPRESSED_SIGNED_RED_RGTC1;
 496    case MESA_FORMAT_RG_RGTC2_UNORM:
 497       return GL_COMPRESSED_RG_RGTC2;
 498    case MESA_FORMAT_RG_RGTC2_SNORM:
 499       return GL_COMPRESSED_SIGNED_RG_RGTC2;
 500
 501    case MESA_FORMAT_L_LATC1_UNORM:
 502       return GL_COMPRESSED_LUMINANCE_LATC1_EXT;
 503    case MESA_FORMAT_L_LATC1_SNORM:
 504       return GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT;
 505    case MESA_FORMAT_LA_LATC2_UNORM:
 506       return GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT;
 507    case MESA_FORMAT_LA_LATC2_SNORM:
 508       return GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT;
 509
 510    case MESA_FORMAT_ETC1_RGB8:
 511       return GL_ETC1_RGB8_OES;
 512    case MESA_FORMAT_ETC2_RGB8:
 513       return GL_COMPRESSED_RGB8_ETC2;
 514    case MESA_FORMAT_ETC2_SRGB8:
 515       return GL_COMPRESSED_SRGB8_ETC2;
 516    case MESA_FORMAT_ETC2_RGBA8_EAC:
 517       return GL_COMPRESSED_RGBA8_ETC2_EAC;
 518    case MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC:
 519       return GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC;
 520    case MESA_FORMAT_ETC2_R11_EAC:
 521       return GL_COMPRESSED_R11_EAC;
 522    case MESA_FORMAT_ETC2_RG11_EAC:
 523       return GL_COMPRESSED_RG11_EAC;
 524    case MESA_FORMAT_ETC2_SIGNED_R11_EAC:
 525       return GL_COMPRESSED_SIGNED_R11_EAC;
 526    case MESA_FORMAT_ETC2_SIGNED_RG11_EAC:
 527       return GL_COMPRESSED_SIGNED_RG11_EAC;
 528    case MESA_FORMAT_ETC2_RGB8_PUNCHTHROUGH_ALPHA1:
 529       return GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 530    case MESA_FORMAT_ETC2_SRGB8_PUNCHTHROUGH_ALPHA1:
 531       return GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2;
 532
 533    case MESA_FORMAT_BPTC_RGBA_UNORM:
 534       return GL_COMPRESSED_RGBA_BPTC_UNORM;
 535    case MESA_FORMAT_BPTC_SRGB_ALPHA_UNORM:
 536       return GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM;
 537    case MESA_FORMAT_BPTC_RGB_SIGNED_FLOAT:
 538       return GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT;
 539    case MESA_FORMAT_BPTC_RGB_UNSIGNED_FLOAT:
 540       return GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT;
 541
 542    default:
 543       _mesa_problem(ctx, "Unexpected mesa texture format in"
 544                     " _mesa_compressed_format_to_glenum()");
 545       return 0;
 546    }
 547 }
 548
 549
 550 /*
 551  * Return the address of the pixel at (col, row, img) in a
 552  * compressed texture image.
 553  * \param col, row, img - image position (3D), should be a multiple of the
 554  *                        format's block size.
 555  * \param format - compressed image format
 556  * \param width - image width (stride) in pixels
 557  * \param image - the image address
 558  * \return address of pixel at (row, col, img)
 559  */
 560 GLubyte *
 561 _mesa_compressed_image_address(GLint col, GLint row, GLint img,
 562                                mesa_format mesaFormat,
 563                                GLsizei width, const GLubyte *image)
 564 {
 565    /* XXX only 2D images implemented, not 3D */
 566    const GLuint blockSize = _mesa_get_format_bytes(mesaFormat);
 567    GLuint bw, bh;
 568    GLint offset;
 569
 570    _mesa_get_format_block_size(mesaFormat, &bw, &bh);
 571
 572    assert(col % bw == 0);
 573    assert(row % bh == 0);
 574
 575    offset = ((width + bw - 1) / bw) * (row / bh) + col / bw;
 576    offset *= blockSize;
 577
 578    return (GLubyte *) image + offset;
 579 }
 580
 581
 582 /**
 583  * Return a texel-fetch function for the given format, or NULL if
 584  * invalid format.
 585  */
 586 compressed_fetch_func
 587 _mesa_get_compressed_fetch_func(mesa_format format)
 588 {
 589    switch (_mesa_get_format_layout(format)) {
 590    case MESA_FORMAT_LAYOUT_S3TC:
 591       return _mesa_get_dxt_fetch_func(format);
 592    case MESA_FORMAT_LAYOUT_FXT1:
 593       return _mesa_get_fxt_fetch_func(format);
 594    case MESA_FORMAT_LAYOUT_RGTC:
 595       return _mesa_get_compressed_rgtc_func(format);
 596    case MESA_FORMAT_LAYOUT_ETC1:
 597       return _mesa_get_etc_fetch_func(format);
 598    case MESA_FORMAT_LAYOUT_BPTC:
 599       return _mesa_get_bptc_fetch_func(format);
 600    default:
 601       return NULL;
 602    }
 603 }
 604
 605
 606 /**
 607  * Decompress a compressed texture image, returning a GL_RGBA/GL_FLOAT image.
 608  * \param srcRowStride  stride in bytes between rows of blocks in the
 609  *                      compressed source image.
 610  */
 611 void
 612 _mesa_decompress_image(mesa_format format, GLuint width, GLuint height,
 613                        const GLubyte *src, GLint srcRowStride,
 614                        GLfloat *dest)
 615 {
 616    compressed_fetch_func fetch;
 617    GLuint i, j;
 618    GLuint bytes, bw, bh;
 619    GLint stride;
 620
 621    bytes = _mesa_get_format_bytes(format);
 622    _mesa_get_format_block_size(format, &bw, &bh);
 623
 624    fetch = _mesa_get_compressed_fetch_func(format);
 625    if (!fetch) {
 626       _mesa_problem(NULL, "Unexpected format in _mesa_decompress_image()");
 627       return;
 628    }
 629
 630    stride = srcRowStride * bh / bytes;
 631
 632    for (j = 0; j < height; j++) {
 633       for (i = 0; i < width; i++) {
 634          fetch(src, stride, i, j, dest);
 635          dest += 4;
 636       }
 637    }
 638 }