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authorDave Airlie <airlied@redhat.com>2011-12-19 16:40:05 +0000
committerDave Airlie <airlied@redhat.com>2011-12-19 20:45:13 +0000
commit35db326de5b173b06344c1a50321a02c2e6e7d93 (patch)
treece4df984908f2635b4a9b06eca0408107c66bfca /src/gallium/docs
parent42696ba16fc548aa680b43a93e7b5929aa429d3c (diff)
tgsi: update documents with some info on texture lookup
this mentions which channels are used for slice and depth comparison values. Signed-off-by: Dave Airlie <airlied@redhat.com> Reviewed-by: Brian Paul <brianp@vmware.com>
Diffstat (limited to 'src/gallium/docs')
-rw-r--r--src/gallium/docs/source/tgsi.rst11
1 files changed, 11 insertions, 0 deletions
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index d7f50b1a6e8..45af528b8e9 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -585,6 +585,17 @@ This instruction replicates its result.
dst = texture_sample(unit, coord, bias)
+ for array textures src0.y contains the slice for 1D,
+ and src0.z contain the slice for 2D.
+ for shadow textures with no arrays, src0.z contains
+ the reference value.
+ for shadow textures with arrays, src0.z contains
+ the reference value for 1D arrays, and src0.w contains
+ the reference value for 2D arrays.
+ There is no way to pass a bias in the .w value for
+ shadow arrays, and GLSL doesn't allow this.
+ GLSL does allow cube shadows maps to take a bias value,
+ and we have to determine how this will look in TGSI.
.. opcode:: TXD - Texture Lookup with Derivatives