Mesa (master): gallium: Document behavior of more lowering pipe caps.

[GitLab Mirror]

Module: Mesa
Branch: master
Commit: cd03f1c6f6d8d63cf73c0ea6fc726bf74279e199
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=cd03f1c6f6d8d63cf73c0ea6fc726bf74279e199

Author: Eric Anholt <eric at anholt.net>
Date:   Wed Jan 20 15:48:53 2021 -0800

gallium: Document behavior of more lowering pipe caps.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8601>

---

 docs/gallium/screen.rst | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/docs/gallium/screen.rst b/docs/gallium/screen.rst
index 49c94704dd2..b0887bfa00e 100644
--- a/docs/gallium/screen.rst
+++ b/docs/gallium/screen.rst
@@ -575,11 +575,20 @@ The integer capabilities:
 * ``PIPE_CAP_GL_SPIRV_VARIABLE_POINTERS``: True if the driver supports Variable Pointers in SPIR-V shaders.
 * ``PIPE_CAP_DEMOTE_TO_HELPER_INVOCATION``: True if driver supports demote keyword in GLSL programs.
 * ``PIPE_CAP_TGSI_TG4_COMPONENT_IN_SWIZZLE``: True if driver wants the TG4 component encoded in sampler swizzle rather than as a separate source.
-* ``PIPE_CAP_FLATSHADE``: Driver supports pipe_rasterizer_state::flatshade.
-* ``PIPE_CAP_ALPHA_TEST``: Driver supports alpha-testing.
+* ``PIPE_CAP_FLATSHADE``: Driver supports pipe_rasterizer_state::flatshade.  Must be 1
+    for non-NIR drivers or gallium nine.
+* ``PIPE_CAP_ALPHA_TEST``: Driver supports alpha-testing.  Must be 1
+    for non-NIR drivers or gallium nine.  If set, frontend may set
+    ``pipe_depth_stencil_alpha_state->alpha_enabled`` and ``alpha_func``.
+    Otherwise, alpha test will be lowered to a comparison and discard_if in the
+    fragment shader.
 * ``PIPE_CAP_POINT_SIZE_FIXED``: Driver supports point-sizes that are fixed,
   as opposed to writing gl_PointSize for every point.
-* ``PIPE_CAP_TWO_SIDED_COLOR``: Driver supports two-sided coloring.
+* ``PIPE_CAP_TWO_SIDED_COLOR``: Driver supports two-sided coloring.  Must be 1
+    for non-NIR drivers.  If set, pipe_rasterizer_state may be set to indicate
+    that backfacing primitives should use the back-side color as the FS input
+    color.  If unset, mesa/st will lower it to gl_FrontFacing reads in the
+    fragment shader.
 * ``PIPE_CAP_CLIP_PLANES``: Driver supports user-defined clip-planes.
 * ``PIPE_CAP_MAX_VERTEX_BUFFERS``: Number of supported vertex buffers.
 * ``PIPE_CAP_OPENCL_INTEGER_FUNCTIONS``: Driver supports extended OpenCL-style integer functions.  This includes averge, saturating additiong, saturating subtraction, absolute difference, count leading zeros, and count trailing zeros.