aboutsummaryrefslogtreecommitdiff
path: root/mesalib/src/mesa/main/texcompress_s3tc.c
blob: 5798406db2d23cd1f60a231981070e1212d9326d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
/*
 * Mesa 3-D graphics library
 * Version:  6.5.3
 *
 * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
 * Copyright (c) 2008 VMware, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


/**
 * \file texcompress_s3tc.c
 * GL_EXT_texture_compression_s3tc support.
 */

#ifndef USE_EXTERNAL_DXTN_LIB
#define USE_EXTERNAL_DXTN_LIB 1
#endif

#include "glheader.h"
#include "imports.h"
#include "colormac.h"
#include "dlopen.h"
#include "image.h"
#include "macros.h"
#include "mfeatures.h"
#include "mtypes.h"
#include "texcompress.h"
#include "texcompress_s3tc.h"
#include "texstore.h"


#if FEATURE_texture_s3tc


#if defined(_WIN32) || defined(WIN32)
#ifdef _DEBUG
#define DXTN_LIBNAME "dxtn_dbg.dll"
#else
#define DXTN_LIBNAME "dxtn.dll"
#endif
#define RTLD_LAZY 0
#define RTLD_GLOBAL 0
#elif defined(__DJGPP__)
#define DXTN_LIBNAME "dxtn.dxe"
#else
#define DXTN_LIBNAME "libtxc_dxtn.so"
#endif

#if FEATURE_EXT_texture_sRGB
/**
 * Convert an 8-bit sRGB value from non-linear space to a
 * linear RGB value in [0, 1].
 * Implemented with a 256-entry lookup table.
 */
static INLINE GLfloat
nonlinear_to_linear(GLubyte cs8)
{
   static GLfloat table[256];
   static GLboolean tableReady = GL_FALSE;
   if (!tableReady) {
      /* compute lookup table now */
      GLuint i;
      for (i = 0; i < 256; i++) {
         const GLfloat cs = UBYTE_TO_FLOAT(i);
         if (cs <= 0.04045) {
            table[i] = cs / 12.92f;
         }
         else {
            table[i] = (GLfloat) pow((cs + 0.055) / 1.055, 2.4);
         }
      }
      tableReady = GL_TRUE;
   }
   return table[cs8];
}
#endif /* FEATURE_EXT_texture_sRGB */

typedef void (*dxtFetchTexelFuncExt)( GLint srcRowstride, GLubyte *pixdata, GLint col, GLint row, GLvoid *texelOut );

dxtFetchTexelFuncExt fetch_ext_rgb_dxt1 = NULL;
dxtFetchTexelFuncExt fetch_ext_rgba_dxt1 = NULL;
dxtFetchTexelFuncExt fetch_ext_rgba_dxt3 = NULL;
dxtFetchTexelFuncExt fetch_ext_rgba_dxt5 = NULL;

typedef void (*dxtCompressTexFuncExt)(GLint srccomps, GLint width,
                                      GLint height, const GLchan *srcPixData,
                                      GLenum destformat, GLubyte *dest,
                                      GLint dstRowStride);

static dxtCompressTexFuncExt ext_tx_compress_dxtn = NULL;

static void *dxtlibhandle = NULL;


void
_mesa_init_texture_s3tc( struct gl_context *ctx )
{
   /* called during context initialization */
   ctx->Mesa_DXTn = GL_FALSE;
#if USE_EXTERNAL_DXTN_LIB
   if (!dxtlibhandle) {
      dxtlibhandle = _mesa_dlopen(DXTN_LIBNAME, 0);
      if (!dxtlibhandle) {
	 _mesa_warning(ctx, "couldn't open " DXTN_LIBNAME ", software DXTn "
	    "compression/decompression unavailable");
      }
      else {
         /* the fetch functions are not per context! Might be problematic... */
         fetch_ext_rgb_dxt1 = (dxtFetchTexelFuncExt)
            _mesa_dlsym(dxtlibhandle, "fetch_2d_texel_rgb_dxt1");
         fetch_ext_rgba_dxt1 = (dxtFetchTexelFuncExt)
            _mesa_dlsym(dxtlibhandle, "fetch_2d_texel_rgba_dxt1");
         fetch_ext_rgba_dxt3 = (dxtFetchTexelFuncExt)
            _mesa_dlsym(dxtlibhandle, "fetch_2d_texel_rgba_dxt3");
         fetch_ext_rgba_dxt5 = (dxtFetchTexelFuncExt)
            _mesa_dlsym(dxtlibhandle, "fetch_2d_texel_rgba_dxt5");
         ext_tx_compress_dxtn = (dxtCompressTexFuncExt)
            _mesa_dlsym(dxtlibhandle, "tx_compress_dxtn");

         if (!fetch_ext_rgb_dxt1 ||
             !fetch_ext_rgba_dxt1 ||
             !fetch_ext_rgba_dxt3 ||
             !fetch_ext_rgba_dxt5 ||
             !ext_tx_compress_dxtn) {
	    _mesa_warning(ctx, "couldn't reference all symbols in "
	       DXTN_LIBNAME ", software DXTn compression/decompression "
	       "unavailable");
            fetch_ext_rgb_dxt1 = NULL;
            fetch_ext_rgba_dxt1 = NULL;
            fetch_ext_rgba_dxt3 = NULL;
            fetch_ext_rgba_dxt5 = NULL;
            ext_tx_compress_dxtn = NULL;
            _mesa_dlclose(dxtlibhandle);
            dxtlibhandle = NULL;
         }
      }
   }
   if (dxtlibhandle) {
      ctx->Mesa_DXTn = GL_TRUE;
   }
#else
   (void) ctx;
#endif
}

/**
 * Store user's image in rgb_dxt1 format.
 */
GLboolean
_mesa_texstore_rgb_dxt1(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 8; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == MESA_FORMAT_RGB_DXT1 ||
          dstFormat == MESA_FORMAT_SRGB_DXT1);
   ASSERT(dstXoffset % 4 == 0);
   ASSERT(dstYoffset % 4 == 0);
   ASSERT(dstZoffset % 4 == 0);
   (void) dstZoffset;
   (void) dstImageOffsets;

   if (srcFormat != GL_RGB ||
       srcType != CHAN_TYPE ||
       ctx->_ImageTransferState ||
       srcPacking->SwapBytes) {
      /* convert image to RGB/GLchan */
      tempImage = _mesa_make_temp_chan_image(ctx, dims,
                                             baseInternalFormat,
                                             _mesa_get_format_base_format(dstFormat),
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      pixels = tempImage;
      srcFormat = GL_RGB;
   }
   else {
      pixels = (const GLchan *) srcAddr;
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat,
                                        texWidth, (GLubyte *) dstAddr);

   if (ext_tx_compress_dxtn) {
      (*ext_tx_compress_dxtn)(3, srcWidth, srcHeight, pixels,
                              GL_COMPRESSED_RGB_S3TC_DXT1_EXT,
                              dst, dstRowStride);
   }
   else {
      _mesa_warning(ctx, "external dxt library not available: texstore_rgb_dxt1");
   }

   if (tempImage)
      free((void *) tempImage);

   return GL_TRUE;
}


/**
 * Store user's image in rgba_dxt1 format.
 */
GLboolean
_mesa_texstore_rgba_dxt1(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 8; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == MESA_FORMAT_RGBA_DXT1 ||
          dstFormat == MESA_FORMAT_SRGBA_DXT1);
   ASSERT(dstXoffset % 4 == 0);
   ASSERT(dstYoffset % 4 == 0);
   ASSERT(dstZoffset % 4 == 0);
   (void) dstZoffset;
   (void) dstImageOffsets;

   if (srcFormat != GL_RGBA ||
       srcType != CHAN_TYPE ||
       ctx->_ImageTransferState ||
       srcPacking->SwapBytes) {
      /* convert image to RGBA/GLchan */
      tempImage = _mesa_make_temp_chan_image(ctx, dims,
                                             baseInternalFormat,
                                             _mesa_get_format_base_format(dstFormat),
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      pixels = tempImage;
      srcFormat = GL_RGBA;
   }
   else {
      pixels = (const GLchan *) srcAddr;
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat,
                                        texWidth, (GLubyte *) dstAddr);
   if (ext_tx_compress_dxtn) {
      (*ext_tx_compress_dxtn)(4, srcWidth, srcHeight, pixels,
                              GL_COMPRESSED_RGBA_S3TC_DXT1_EXT,
                              dst, dstRowStride);
   }
   else {
      _mesa_warning(ctx, "external dxt library not available: texstore_rgba_dxt1");
   }

   if (tempImage)
      free((void*) tempImage);

   return GL_TRUE;
}


/**
 * Store user's image in rgba_dxt3 format.
 */
GLboolean
_mesa_texstore_rgba_dxt3(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 16; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == MESA_FORMAT_RGBA_DXT3 ||
          dstFormat == MESA_FORMAT_SRGBA_DXT3);
   ASSERT(dstXoffset % 4 == 0);
   ASSERT(dstYoffset % 4 == 0);
   ASSERT(dstZoffset % 4 == 0);
   (void) dstZoffset;
   (void) dstImageOffsets;

   if (srcFormat != GL_RGBA ||
       srcType != CHAN_TYPE ||
       ctx->_ImageTransferState ||
       srcPacking->SwapBytes) {
      /* convert image to RGBA/GLchan */
      tempImage = _mesa_make_temp_chan_image(ctx, dims,
                                             baseInternalFormat,
                                             _mesa_get_format_base_format(dstFormat),
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      pixels = tempImage;
   }
   else {
      pixels = (const GLchan *) srcAddr;
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat,
                                        texWidth, (GLubyte *) dstAddr);
   if (ext_tx_compress_dxtn) {
      (*ext_tx_compress_dxtn)(4, srcWidth, srcHeight, pixels,
                              GL_COMPRESSED_RGBA_S3TC_DXT3_EXT,
                              dst, dstRowStride);
   }
   else {
      _mesa_warning(ctx, "external dxt library not available: texstore_rgba_dxt3");
   }

   if (tempImage)
      free((void *) tempImage);

   return GL_TRUE;
}


/**
 * Store user's image in rgba_dxt5 format.
 */
GLboolean
_mesa_texstore_rgba_dxt5(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 16; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == MESA_FORMAT_RGBA_DXT5 ||
          dstFormat == MESA_FORMAT_SRGBA_DXT5);
   ASSERT(dstXoffset % 4 == 0);
   ASSERT(dstYoffset % 4 == 0);
   ASSERT(dstZoffset % 4 == 0);
   (void) dstZoffset;
   (void) dstImageOffsets;

   if (srcFormat != GL_RGBA ||
       srcType != CHAN_TYPE ||
       ctx->_ImageTransferState ||
       srcPacking->SwapBytes) {
      /* convert image to RGBA/GLchan */
      tempImage = _mesa_make_temp_chan_image(ctx, dims,
                                             baseInternalFormat,
                                   	     _mesa_get_format_base_format(dstFormat),
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      pixels = tempImage;
   }
   else {
      pixels = (const GLchan *) srcAddr;
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat,
                                        texWidth, (GLubyte *) dstAddr);
   if (ext_tx_compress_dxtn) {
      (*ext_tx_compress_dxtn)(4, srcWidth, srcHeight, pixels,
                              GL_COMPRESSED_RGBA_S3TC_DXT5_EXT,
                              dst, dstRowStride);
   }
   else {
      _mesa_warning(ctx, "external dxt library not available: texstore_rgba_dxt5");
   }

   if (tempImage)
      free((void *) tempImage);

   return GL_TRUE;
}


static void
fetch_texel_2d_rgb_dxt1( const struct gl_texture_image *texImage,
                         GLint i, GLint j, GLint k, GLchan *texel )
{
   (void) k;
   if (fetch_ext_rgb_dxt1) {
      ASSERT (sizeof(GLchan) == sizeof(GLubyte));
      fetch_ext_rgb_dxt1(texImage->RowStride,
                         (GLubyte *)(texImage)->Data, i, j, texel);
   }
   else
      _mesa_debug(NULL, "attempted to decode s3tc texture without library available: fetch_texel_2d_rgb_dxt1");
}


void
_mesa_fetch_texel_2d_f_rgb_dxt1(const struct gl_texture_image *texImage,
                                GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgb_dxt1(texImage, i, j, k, rgba);
   texel[RCOMP] = CHAN_TO_FLOAT(rgba[RCOMP]);
   texel[GCOMP] = CHAN_TO_FLOAT(rgba[GCOMP]);
   texel[BCOMP] = CHAN_TO_FLOAT(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}


static void
fetch_texel_2d_rgba_dxt1( const struct gl_texture_image *texImage,
                          GLint i, GLint j, GLint k, GLchan *texel )
{
   (void) k;
   if (fetch_ext_rgba_dxt1) {
      fetch_ext_rgba_dxt1(texImage->RowStride,
                          (GLubyte *)(texImage)->Data, i, j, texel);
   }
   else
      _mesa_debug(NULL, "attempted to decode s3tc texture without library available: fetch_texel_2d_rgba_dxt1\n");
}


void
_mesa_fetch_texel_2d_f_rgba_dxt1(const struct gl_texture_image *texImage,
                                 GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgba_dxt1(texImage, i, j, k, rgba);
   texel[RCOMP] = CHAN_TO_FLOAT(rgba[RCOMP]);
   texel[GCOMP] = CHAN_TO_FLOAT(rgba[GCOMP]);
   texel[BCOMP] = CHAN_TO_FLOAT(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}


static void
fetch_texel_2d_rgba_dxt3( const struct gl_texture_image *texImage,
                          GLint i, GLint j, GLint k, GLchan *texel )
{
   (void) k;
   if (fetch_ext_rgba_dxt3) {
      ASSERT (sizeof(GLchan) == sizeof(GLubyte));
      fetch_ext_rgba_dxt3(texImage->RowStride, (GLubyte *)(texImage)->Data,
                          i, j, texel);
   }
   else
      _mesa_debug(NULL, "attempted to decode s3tc texture without library available: fetch_texel_2d_rgba_dxt3\n");
}


void
_mesa_fetch_texel_2d_f_rgba_dxt3(const struct gl_texture_image *texImage,
                                 GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgba_dxt3(texImage, i, j, k, rgba);
   texel[RCOMP] = CHAN_TO_FLOAT(rgba[RCOMP]);
   texel[GCOMP] = CHAN_TO_FLOAT(rgba[GCOMP]);
   texel[BCOMP] = CHAN_TO_FLOAT(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}


static void
fetch_texel_2d_rgba_dxt5( const struct gl_texture_image *texImage,
                          GLint i, GLint j, GLint k, GLchan *texel )
{
   (void) k;
   if (fetch_ext_rgba_dxt5) {
      fetch_ext_rgba_dxt5(texImage->RowStride, (GLubyte *)(texImage)->Data,
                          i, j, texel);
   }
   else
      _mesa_debug(NULL, "attempted to decode s3tc texture without library available: fetch_texel_2d_rgba_dxt5\n");
}


void
_mesa_fetch_texel_2d_f_rgba_dxt5(const struct gl_texture_image *texImage,
                                 GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgba_dxt5(texImage, i, j, k, rgba);
   texel[RCOMP] = CHAN_TO_FLOAT(rgba[RCOMP]);
   texel[GCOMP] = CHAN_TO_FLOAT(rgba[GCOMP]);
   texel[BCOMP] = CHAN_TO_FLOAT(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}

#if FEATURE_EXT_texture_sRGB
void
_mesa_fetch_texel_2d_f_srgb_dxt1( const struct gl_texture_image *texImage,
                                  GLint i, GLint j, GLint k, GLfloat *texel )
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgb_dxt1(texImage, i, j, k, rgba);
   texel[RCOMP] = nonlinear_to_linear(rgba[RCOMP]);
   texel[GCOMP] = nonlinear_to_linear(rgba[GCOMP]);
   texel[BCOMP] = nonlinear_to_linear(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}

void
_mesa_fetch_texel_2d_f_srgba_dxt1(const struct gl_texture_image *texImage,
                                  GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgba_dxt1(texImage, i, j, k, rgba);
   texel[RCOMP] = nonlinear_to_linear(rgba[RCOMP]);
   texel[GCOMP] = nonlinear_to_linear(rgba[GCOMP]);
   texel[BCOMP] = nonlinear_to_linear(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}

void
_mesa_fetch_texel_2d_f_srgba_dxt3(const struct gl_texture_image *texImage,
                                  GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgba_dxt3(texImage, i, j, k, rgba);
   texel[RCOMP] = nonlinear_to_linear(rgba[RCOMP]);
   texel[GCOMP] = nonlinear_to_linear(rgba[GCOMP]);
   texel[BCOMP] = nonlinear_to_linear(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}

void
_mesa_fetch_texel_2d_f_srgba_dxt5(const struct gl_texture_image *texImage,
                                  GLint i, GLint j, GLint k, GLfloat *texel)
{
   /* just sample as GLchan and convert to float here */
   GLchan rgba[4];
   fetch_texel_2d_rgba_dxt5(texImage, i, j, k, rgba);
   texel[RCOMP] = nonlinear_to_linear(rgba[RCOMP]);
   texel[GCOMP] = nonlinear_to_linear(rgba[GCOMP]);
   texel[BCOMP] = nonlinear_to_linear(rgba[BCOMP]);
   texel[ACOMP] = CHAN_TO_FLOAT(rgba[ACOMP]);
}
#endif /* FEATURE_EXT_texture_sRGB */


#endif /* FEATURE_texture_s3tc */