Merge commit 'lb2/arb_fragment_coord_conventions'

2 files changed, 52 insertions, 3 deletions

diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst
index f2421c74ae4..0507b81627b 100644
--- a/src/gallium/docs/source/screen.rst
+++ b/src/gallium/docs/source/screen.rst
@@ -57,6 +57,14 @@ The integer capabilities:
   only permit binding one constant buffer per shader, and the shaders will
   not permit two-dimensional access to constants.
 * ``MAX_CONST_BUFFER_SIZE``: Maximum byte size of a single constant buffer.
+* ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_UPPER_LEFT``: Whether the TGSI property
+  FS_COORD_ORIGIN with value UPPER_LEFT is supported
+* ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_LOWER_LEFT``: Whether the TGSI property
+  FS_COORD_ORIGIN with value LOWER_LEFT is supported
+* ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_HALF_INTEGER``: Whether the TGSI
+  property FS_COORD_PIXEL_CENTER with value HALF_INTEGER is supported
+* ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_INTEGER``: Whether the TGSI
+  property FS_COORD_PIXEL_CENTER with value INTEGER is supported
 
 The floating-point capabilities:
 
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index 2c34a6bae5e..3e702ceeda4 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -1319,9 +1319,8 @@ are the Cartesian coordinates, and ``w`` is the homogenous coordinate and used
 for the perspective divide, if enabled.
 
 As a vertex shader output, position should be scaled to the viewport. When
-used in fragment shaders, position will ---
-
-XXX --- wait a minute. Should position be in [0,1] for x and y?
+used in fragment shaders, position will be in window coordinates. The convention
+used depends on the FS_COORD_ORIGIN and FS_COORD_PIXEL_CENTER properties.
 
 XXX additionally, is there a way to configure the perspective divide? it's
 accelerated on most chipsets AFAIK...
@@ -1400,3 +1399,45 @@ TGSI_SEMANTIC_EDGEFLAG
 """"""""""""""""""""""
 
 XXX no clue
+
+
+Properties
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+  Properties are general directives that apply to the whole TGSI program.
+
+FS_COORD_ORIGIN
+"""""""""""""""
+
+Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
+The default value is UPPER_LEFT.
+
+If UPPER_LEFT, the position will be (0,0) at the upper left corner and
+increase downward and rightward.
+If LOWER_LEFT, the position will be (0,0) at the lower left corner and
+increase upward and rightward.
+
+OpenGL defaults to LOWER_LEFT, and is configurable with the
+GL_ARB_fragment_coord_conventions extension.
+
+DirectX 9/10 use UPPER_LEFT.
+
+FS_COORD_PIXEL_CENTER
+"""""""""""""""""""""
+
+Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
+The default value is HALF_INTEGER.
+
+If HALF_INTEGER, the fractionary part of the position will be 0.5
+If INTEGER, the fractionary part of the position will be 0.0
+
+Note that this does not affect the set of fragments generated by
+rasterization, which is instead controlled by gl_rasterization_rules in the
+rasterizer.
+
+OpenGL defaults to HALF_INTEGER, and is configurable with the
+GL_ARB_fragment_coord_conventions extension.
+
+DirectX 9 uses INTEGER.
+DirectX 10 uses HALF_INTEGER.