Add Roland Scheidegger's S3TC patch. This patch does not implement the

(patented) S3TC/DXTC algorithms, but adds an option to dlopen a library module
providing functions to do so.  Because it uses dlopen, it is only enabled if
USE_EXTERNAL_DXTN_LIB=1 is defined (which is only in linux-dri config, so far).
It adds support for S3TC to several DRI drivers, and adds a DRI config option to
force enabling S3TC even if the software compression/decompression is
unavailable.  This may allow people to use apps that require S3TC even though
they don't have a license to implement the patented material themselves, if
those apps use precompressed textures.

Ideally we would get permission from the current holder of the patents to
implement the algorithm in Mesa, at which point the dlopen mess could go away.
Until then, this allows some to run applications they couldn't otherwise, and
hopefully will provide us with more push to get the final step of getting that
permission done.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i915/i830_texstate.c b/src/mesa/drivers/dri/i915/i830_texstate.c
index a393fd1d52e..ba452279baf 100644
--- a/src/mesa/drivers/dri/i915/i830_texstate.c
+++ b/src/mesa/drivers/dri/i915/i830_texstate.c
@@ -125,6 +125,25 @@ static GLboolean i830SetTexImages( i830ContextPtr i830,
      textureFormat = MAPSURF_COMPRESSED | MT_COMPRESS_FXT1;
      break;
 
+   case MESA_FORMAT_RGBA_DXT1:
+   case MESA_FORMAT_RGB_DXT1:
+     /* 
+      * DXTn pitches are Width/4 * blocksize in bytes 
+      * for DXT1: blocksize=8 so Width/4*8 = Width * 2 
+      * for DXT3/5: blocksize=16 so Width/4*16 = Width * 4
+      */
+     t->intel.texelBytes = 2;
+     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_DXT1);
+     break;
+   case MESA_FORMAT_RGBA_DXT3:
+     t->intel.texelBytes = 4;
+     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_DXT2_3);
+     break;
+   case MESA_FORMAT_RGBA_DXT5:
+     t->intel.texelBytes = 4;
+     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_DXT4_5);
+     break;
+
    default:
       fprintf(stderr, "%s: bad image format\n", __FUNCTION__);
       abort();