[Mesa-dev] [PATCH] tgsi: update documents with some info on texture lookup

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

this mentions which channels are used for slice and depth comparison values.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 src/gallium/docs/source/tgsi.rst |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index d7f50b1..45af528 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
 
-- 
1.7.7.3