texcompress_s3tc.c   [plain text]

/*
 * Mesa 3-D graphics library
 * Version:  6.5.3
 *
 * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
 *
 * 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 0
#endif

#include "glheader.h"
#include "imports.h"
#include "colormac.h"
#include "context.h"
#include "convolve.h"
#include "image.h"
#include "texcompress.h"
#include "texformat.h"
#include "texstore.h"

#if USE_EXTERNAL_DXTN_LIB && !defined(__MINGW32__)
#include <dlfcn.h>
#endif

#ifdef __MINGW32__
#define DXTN_LIBNAME "dxtn.dll"
#define RTLD_LAZY 0
#define RTLD_GLOBAL 0
#elif defined(__DJGPP__)
#define DXTN_LIBNAME "dxtn.dxe"
#else
#define DXTN_LIBNAME "libtxc_dxtn.so"
#endif


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;


typedef void (*GenericFunc)(void);


/**
 * Wrapper for dlopen().
 * XXX Probably move this and the following wrappers into imports.h someday.
 */
static void *
_mesa_dlopen(const char *libname, int flags)
{
#if USE_EXTERNAL_DXTN_LIB
#ifdef __MINGW32__
   return LoadLibrary(libname);
#else
   return dlopen(libname, flags);
#endif
#else
   return NULL;
#endif /* USE_EXTERNAL_DXTN_LIB */
}


/**
 * Wrapper for dlsym() that does a cast to a generic function type,
 * rather than a void *.  This reduces the number of warnings that are
 * generated.
 */
static GenericFunc
_mesa_dlsym(void *handle, const char *fname)
{
#if USE_EXTERNAL_DXTN_LIB
#ifdef __MINGW32__
   return (GenericFunc) GetProcAddress(handle, fname);
#elif defined(__DJGPP__)
   /* need '_' prefix on symbol names */
   char fname2[1000];
   fname2[0] = '_';
   _mesa_strncpy(fname2 + 1, fname, 998);
   fname2[999] = 0;
   return (GenericFunc) dlsym(handle, fname2);
#else
   return (GenericFunc) dlsym(handle, fname);
#endif
#else
   return (GenericFunc) NULL;
#endif /* USE_EXTERNAL_DXTN_LIB */
}


/**
 * Wrapper for dlclose().
 */
static void
_mesa_dlclose(void *handle)
{
#if USE_EXTERNAL_DXTN_LIB
#ifdef __MINGW32__
   FreeLibrary(handle);
#else
   dlclose(handle);
#endif
#endif
}



void
_mesa_init_texture_s3tc( GLcontext *ctx )
{
   /* called during context initialization */
   ctx->Mesa_DXTn = GL_FALSE;
#if USE_EXTERNAL_DXTN_LIB
   if (!dxtlibhandle) {
      dxtlibhandle = _mesa_dlopen(DXTN_LIBNAME, RTLD_LAZY | RTLD_GLOBAL);
      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;
      _mesa_warning(ctx, "software DXTn compression/decompression available");
   }
#else
   (void) ctx;
#endif
}

/**
 * Called via TexFormat->StoreImage to store an RGB_DXT1 texture.
 */
static GLboolean
texstore_rgb_dxt1(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLint srcRowStride;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 8; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == &_mesa_texformat_rgb_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,
                                             dstFormat->BaseFormat,
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      _mesa_adjust_image_for_convolution(ctx, dims, &srcWidth, &srcHeight);
      pixels = tempImage;
      srcRowStride = 3 * srcWidth;
      srcFormat = GL_RGB;
   }
   else {
      pixels = (const GLchan *) srcAddr;
      srcRowStride = _mesa_image_row_stride(srcPacking, srcWidth, srcFormat,
                                            srcType) / sizeof(GLchan);
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat->MesaFormat,
                                        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");
   }

   if (tempImage)
      _mesa_free((void *) tempImage);

   return GL_TRUE;
}


/**
 * Called via TexFormat->StoreImage to store an RGBA_DXT1 texture.
 */
static GLboolean
texstore_rgba_dxt1(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLint srcRowStride;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 8; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == &_mesa_texformat_rgba_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,
                                             dstFormat->BaseFormat,
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      _mesa_adjust_image_for_convolution(ctx, dims, &srcWidth, &srcHeight);
      pixels = tempImage;
      srcRowStride = 4 * srcWidth;
      srcFormat = GL_RGBA;
   }
   else {
      pixels = (const GLchan *) srcAddr;
      srcRowStride = _mesa_image_row_stride(srcPacking, srcWidth, srcFormat,
                                            srcType) / sizeof(GLchan);
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat->MesaFormat,
                                        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");
   }

   if (tempImage)
      _mesa_free((void*) tempImage);

   return GL_TRUE;
}


/**
 * Called via TexFormat->StoreImage to store an RGBA_DXT3 texture.
 */
static GLboolean
texstore_rgba_dxt3(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLint srcRowStride;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 16; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == &_mesa_texformat_rgba_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,
                                             dstFormat->BaseFormat,
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      _mesa_adjust_image_for_convolution(ctx, dims, &srcWidth, &srcHeight);
      pixels = tempImage;
      srcRowStride = 4 * srcWidth;
   }
   else {
      pixels = (const GLchan *) srcAddr;
      srcRowStride = _mesa_image_row_stride(srcPacking, srcWidth, srcFormat,
                                            srcType) / sizeof(GLchan);
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat->MesaFormat,
                                        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");
   }

   if (tempImage)
      _mesa_free((void *) tempImage);

   return GL_TRUE;
}


/**
 * Called via TexFormat->StoreImage to store an RGBA_DXT5 texture.
 */
static GLboolean
texstore_rgba_dxt5(TEXSTORE_PARAMS)
{
   const GLchan *pixels;
   GLint srcRowStride;
   GLubyte *dst;
   const GLint texWidth = dstRowStride * 4 / 16; /* a bit of a hack */
   const GLchan *tempImage = NULL;

   ASSERT(dstFormat == &_mesa_texformat_rgba_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,
                                             dstFormat->BaseFormat,
                                             srcWidth, srcHeight, srcDepth,
                                             srcFormat, srcType, srcAddr,
                                             srcPacking);
      if (!tempImage)
         return GL_FALSE; /* out of memory */
      _mesa_adjust_image_for_convolution(ctx, dims, &srcWidth, &srcHeight);
      pixels = tempImage;
      srcRowStride = 4 * srcWidth;
   }
   else {
      pixels = (const GLchan *) srcAddr;
      srcRowStride = _mesa_image_row_stride(srcPacking, srcWidth, srcFormat,
                                            srcType) / sizeof(GLchan);
   }

   dst = _mesa_compressed_image_address(dstXoffset, dstYoffset, 0,
                                        dstFormat->MesaFormat,
                                        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");
   }

   if (tempImage)
      _mesa_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\n");
}


static void
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\n");
}


static void
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\n");
}


static void
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\n");
}


static void
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]);
}


const struct gl_texture_format _mesa_texformat_rgb_dxt1 = {
   MESA_FORMAT_RGB_DXT1,		/* MesaFormat */
   GL_RGB,				/* BaseFormat */
   GL_UNSIGNED_NORMALIZED_ARB,		/* DataType */
   4, /*approx*/			/* RedBits */
   4, /*approx*/			/* GreenBits */
   4, /*approx*/			/* BlueBits */
   0,					/* AlphaBits */
   0,					/* LuminanceBits */
   0,					/* IntensityBits */
   0,					/* IndexBits */
   0,					/* DepthBits */
   0,					/* StencilBits */
   0,					/* TexelBytes */
   texstore_rgb_dxt1,			/* StoreTexImageFunc */
   NULL, /*impossible*/ 		/* FetchTexel1D */
   fetch_texel_2d_rgb_dxt1, 		/* FetchTexel2D */
   NULL, /*impossible*/ 		/* FetchTexel3D */
   NULL, /*impossible*/ 		/* FetchTexel1Df */
   fetch_texel_2d_f_rgb_dxt1, 		/* FetchTexel2Df */
   NULL, /*impossible*/ 		/* FetchTexel3Df */
   NULL					/* StoreTexel */
};

#if FEATURE_EXT_texture_sRGB
const struct gl_texture_format _mesa_texformat_srgb_dxt1 = {
   MESA_FORMAT_SRGB_DXT1,		/* MesaFormat */
   GL_RGB,				/* BaseFormat */
   GL_UNSIGNED_NORMALIZED_ARB,		/* DataType */
   4, /*approx*/			/* RedBits */
   4, /*approx*/			/* GreenBits */
   4, /*approx*/			/* BlueBits */
   0,					/* AlphaBits */
   0,					/* LuminanceBits */
   0,					/* IntensityBits */
   0,					/* IndexBits */
   0,					/* DepthBits */
   0,					/* StencilBits */
   0,					/* TexelBytes */
   texstore_rgb_dxt1,			/* StoreTexImageFunc */
   NULL, /*impossible*/ 		/* FetchTexel1D */
   fetch_texel_2d_rgb_dxt1, 		/* FetchTexel2D */
   NULL, /*impossible*/ 		/* FetchTexel3D */
   NULL, /*impossible*/ 		/* FetchTexel1Df */
   fetch_texel_2d_f_rgb_dxt1, 		/* FetchTexel2Df */
   NULL, /*impossible*/ 		/* FetchTexel3Df */
   NULL					/* StoreTexel */
};
#endif

const struct gl_texture_format _mesa_texformat_rgba_dxt1 = {
   MESA_FORMAT_RGBA_DXT1,		/* MesaFormat */
   GL_RGBA,				/* BaseFormat */
   GL_UNSIGNED_NORMALIZED_ARB,		/* DataType */
   4, /*approx*/			/* RedBits */
   4, /*approx*/			/* GreenBits */
   4, /*approx*/			/* BlueBits */
   1, /*approx*/			/* AlphaBits */
   0,					/* LuminanceBits */
   0,					/* IntensityBits */
   0,					/* IndexBits */
   0,					/* DepthBits */
   0,					/* StencilBits */
   0,					/* TexelBytes */
   texstore_rgba_dxt1,			/* StoreTexImageFunc */
   NULL, /*impossible*/ 		/* FetchTexel1D */
   fetch_texel_2d_rgba_dxt1, 		/* FetchTexel2D */
   NULL, /*impossible*/ 		/* FetchTexel3D */
   NULL, /*impossible*/ 		/* FetchTexel1Df */
   fetch_texel_2d_f_rgba_dxt1, 		/* FetchTexel2Df */
   NULL, /*impossible*/ 		/* FetchTexel3Df */
   NULL					/* StoreTexel */
};

const struct gl_texture_format _mesa_texformat_rgba_dxt3 = {
   MESA_FORMAT_RGBA_DXT3,		/* MesaFormat */
   GL_RGBA,				/* BaseFormat */
   GL_UNSIGNED_NORMALIZED_ARB,		/* DataType */
   4, /*approx*/			/* RedBits */
   4, /*approx*/			/* GreenBits */
   4, /*approx*/			/* BlueBits */
   4, /*approx*/			/* AlphaBits */
   0,					/* LuminanceBits */
   0,					/* IntensityBits */
   0,					/* IndexBits */
   0,					/* DepthBits */
   0,					/* StencilBits */
   0,					/* TexelBytes */
   texstore_rgba_dxt3,			/* StoreTexImageFunc */
   NULL, /*impossible*/ 		/* FetchTexel1D */
   fetch_texel_2d_rgba_dxt3, 		/* FetchTexel2D */
   NULL, /*impossible*/ 		/* FetchTexel3D */
   NULL, /*impossible*/ 		/* FetchTexel1Df */
   fetch_texel_2d_f_rgba_dxt3, 		/* FetchTexel2Df */
   NULL, /*impossible*/ 		/* FetchTexel3Df */
   NULL					/* StoreTexel */
};

const struct gl_texture_format _mesa_texformat_rgba_dxt5 = {
   MESA_FORMAT_RGBA_DXT5,		/* MesaFormat */
   GL_RGBA,				/* BaseFormat */
   GL_UNSIGNED_NORMALIZED_ARB,		/* DataType */
   4,/*approx*/				/* RedBits */
   4,/*approx*/				/* GreenBits */
   4,/*approx*/				/* BlueBits */
   4,/*approx*/				/* AlphaBits */
   0,					/* LuminanceBits */
   0,					/* IntensityBits */
   0,					/* IndexBits */
   0,					/* DepthBits */
   0,					/* StencilBits */
   0,					/* TexelBytes */
   texstore_rgba_dxt5,			/* StoreTexImageFunc */
   NULL, /*impossible*/ 		/* FetchTexel1D */
   fetch_texel_2d_rgba_dxt5, 		/* FetchTexel2D */
   NULL, /*impossible*/ 		/* FetchTexel3D */
   NULL, /*impossible*/ 		/* FetchTexel1Df */
   fetch_texel_2d_f_rgba_dxt5, 		/* FetchTexel2Df */
   NULL, /*impossible*/ 		/* FetchTexel3Df */
   NULL					/* StoreTexel */
};