Mesa (master): gallium/docs: document behavior of set_sample_mask()

[Brian Paul]

Module: Mesa
Branch: master
Commit: c27a6c45c2f225f5a9966546893252b0435bc371
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=c27a6c45c2f225f5a9966546893252b0435bc371

Author: Brian Paul <brianp at vmware.com>
Date:   Tue Dec 12 20:32:06 2017 -0700

gallium/docs: document behavior of set_sample_mask()

The sample mask is used even if msaa is not explicity enabled when we
have a framebuffer with multisampled surfaces.  That's DX behavior and
what the Radeon drivers do.  Not sure about other drivers at this point.

Reviewed-by: Roland Scheidegger <sroland at vmware.com>

---

 src/gallium/docs/source/context.rst | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/gallium/docs/source/context.rst b/src/gallium/docs/source/context.rst
index 9d069b37d7..0ac7340242 100644
--- a/src/gallium/docs/source/context.rst
+++ b/src/gallium/docs/source/context.rst
@@ -64,7 +64,10 @@ objects. They all follow simple, one-method binding calls, e.g.
 * ``set_stencil_ref`` sets the stencil front and back reference values
   which are used as comparison values in stencil test.
 * ``set_blend_color``
-* ``set_sample_mask``
+* ``set_sample_mask``  sets the per-context multisample sample mask.  Note
+  that this takes effect even if multisampling is not explicitly enabled if
+  the frambuffer surface(s) are multisampled.  Also, this mask is AND-ed
+  with the optional fragment shader sample mask output (when emitted).
 * ``set_min_samples`` sets the minimum number of samples that must be run.
 * ``set_clip_state``
 * ``set_polygon_stipple``