gallium: add TGSI_SEMANTIC_TEXCOORD,PCOORD v3

This makes it possible to identify gl_TexCoord and gl_PointCoord
for drivers where sprite coordinate replacement is restricted.

The new PIPE_CAP_TGSI_TEXCOORD decides whether these varyings
should be hidden behind the GENERIC semantic or not.

With this patch only nvc0 and nv30 will request that they be used.

v2: introduce a CAP so other drivers don't have to bother with
the new semantic

v3: adapt to introduction gl_varying_slot enum

1 files changed, 8 insertions, 0 deletions

diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst
index 68d1a35cc73..0550a30714a 100644
--- a/src/gallium/docs/source/screen.rst
+++ b/src/gallium/docs/source/screen.rst
@@ -137,6 +137,14 @@ The integer capabilities:
 * ``PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT``: Describes the required
   alignment for pipe_sampler_view::u.buf.first_element, in bytes.
   If a driver does not support first/last_element, it should return 0.
+* ``PIPE_CAP_TGSI_TEXCOORD``: This CAP describes a hw limitation.
+  If true, the hardware cannot replace arbitrary shader inputs with sprite
+  coordinates and hence the inputs that are desired to be replaceable must
+  be declared with TGSI_SEMANTIC_TEXCOORD instead of TGSI_SEMANTIC_GENERIC.
+  The rasterizer's sprite_coord_enable state therefore also applies to the
+  TEXCOORD semantic.
+  Also, TGSI_SEMANTIC_PCOORD becomes available, which labels a fragment shader
+  input that will always be replaced with sprite coordinates.
 
 
 .. _pipe_capf: